11-28 KDP Ebook

Ace the Boards: Neoplastic Hematopathology ~ 0 ~

Ace The Boards: Neoplastic Hematopathology ~ 1 ~

Ace the Boards: 

Neoplastic 

Hematopathology 

Akanksha Gupta 

Nupur Sharma 


Copyright © 2020 Akanksha Gupta, MD, FASCP 

Twitter: @Hemepath_Doc 

Dr.Akanksha_Gupta@yahoo.com 

All rights reserved. 

ISBN: 9798664510539 


CONTRIBUTORS: AUTHORS 

AKANKSHA GUPTA, MBBS, MD, FASCP 

Hematopathology Fellow 

Memorial Sloan Kettering Cancer Center 

New York, NY 

KAMRAN MIRZA, MD, PhD 

Associate Professor 

Department of Pathology and Lab Medicine 

Loyola University Medical Center, Chicago, IL 

NUPUR SHARMA, MBBS, MD 

PGY3 Resident (AP/CP) 

East Carolina University, Greenville, NC 

Future Hematopathology fellow (2022-23) 

University of North Carolina at Chapel Hill 

SHRUTIKA JAVA (NÉE MUNOT), MBBS, MD 

Assistant Professor, BYL Nair Charitable Hospital 

and TN Medical College, Mumbai, India 

Prior HBNI Fellow in Hematopathology 

Tata Memorial Hospital, Mumbai, India 

KSHITIJA M KALE, MBBS 


Lokmanya Tilak Municipal Medical College 

Sion, Mumbai, India 

RAMA DEVI, MBBS, MD 

Assistant Professor (Pathology) 

SVS Medical college, 

Mahabubnagar, Telangana, India 

NIDHI KATARIA, MBBS 


Zucker School of Medicine at Hofstra/Northwell, 

New York, NY 

JEREMIAH XAVIER KARRS, DO 

Clinical Fellow in Hematopathology 

National Institute of Health 

Bethesda, MD 

VANYA JAITLY, MBBS, MD 

Hematopathology Fellow 

University of Pittsburgh Medical Center 

Pittsburgh, PA 

PRIYA SKARIA, MBBS, MD 

Pediatric Pathology Fellow 

Prior Hematopathology Fellow 

Washington University in St Louis, MO 

AAKASH BHATIA, MBBS, MD 


University of Texas Health Science Center, 

Houston, TX 

Future Hematopathology Fellow (2021 – 23) 

MD Anderson Cancer Center, TX 

LAURA BROWN, MD 

Assistant Clinical Professor (Hematopathology) 

University of California 

San Francisco, CA 

S. KANNAN, MBBS 


Christian Medical College, Vellore, India 


CONTRIBUTORS 

MAIN EDITOR 

AKANKSHA GUPTA, MBBS, MD, FASCP 

Hematopathology fellow 

Memorial Sloan Kettering Cancer Center 

New York, NY 

OTHER EDITORS 

KAMRAN MIRZA, MD, PHD 

Associate Professor 

Department of Pathology and Lab Medicine 

Loyola University Medical Center, Chicago, IL 

NUPUR SHARMA, MBBS, MD 


East Carolina University, Greenville, NC 

Future Hematopathology fellow (2022-23) 

University of North Carolina at Chapel Hill 

LYNH NGUYEN, MD 

Assistant Professor at University of South Florida’s 

Morsani College of Medicine 

Hematopathologist at James A. Haley Veterans’ 

Hospital 

Tampa, FL 33612 

LAILA NOMANI, MD 

Assistant Professor at Medical College of 

Wisconsin and Froedert Hospital. 

Wauwatosa, WI 

COVER (RBC/WBC) PATHART COURTESY 

AHLAM NAIF ALAHMEDI, MBBS, MD 

Pathology Resident (R5) 

National Guard Hospital 

Riyadh, Saudi Arabia 

REVIEWERS 

PRAJESH ADHIKARI, MD 

Prior Hematopathology fellow 

Current Dermatopathology fellow 

University of Vermont Medical Center 

Burlington, VT 

KRISTIN STICCO DO, MS 

Hematopathologist, Transfusion medicine 

physician 

Northwell Health, New York, NY 

SANDEEP RAO, MBBS, MD, DM 

Consultant Hematopathologist 

Columbia Asia hospitals, Bangalore, India 

(MD path and DM hematopathology from PGI 

Chandigarh, India) 

ROSALINDA PEÑALOZA RAMIREZ, MD 

Hematopathologist and Surgical Pathologist 

Special Regional Hospital of Oaxaca 

Oaxaca, Mexico 

NOUR ALMOZAIN, MD 

King Saud University Medical City, King Saud 

University 

Riyadh, Saudi Arabia 

SIDDARTHA KASULA, MBBS, DNB 

Consultant pathologist 

Krishna institute of medical sciences 

Secunderabad, India 

ASHISH GUPTA, MD, FAAP 

Mercy Health 

Grand Rapids, MI 


FOREWORD 

Rarely does one come across the winning combination of boundless talent, remarkable wit, and unshakeable 

dedication like seen in the group of exceptional pathologists that have authored and edited this text. As 

someone who is passionate about teaching, I was intrigued by the idea of a hematopathology ‘book club’ that 

was proposed on Twitter during the raging COVID-19 pandemic. I was curious and joined one of their 

sessions - their closed chat group of “note writers.” Their pursuit and success have been inspirational! Little 

did I know, the authors would go ahead and make a book out of their notes! It was a privilege to see this highly 

motivated team evolve from “note writers” to “book authors.” 

Hematopathology is a mesmerizing, rapidly evolving, and (to the junior pathology trainee) a challenging 

subspecialty. Medical students, graduate students, pathology residents, and hematopathology fellows all 

actively look for a comprehensive review book (beyond the required reading) and typically end up buying and 

perusing many different books. To be honest, I find that this one book will replace most others and will serve 

as an invaluable resource for hematopathology review. 

Ace the Boards: Neoplastic Hematopathology is essentially “Neoplastic Hematopathology Made Easy”!! It is 

well-organized with facts that are presented in a manner that is easy to read, understand, and retain. This is 

further enhanced by excellent illustrations and tables, which will strengthen the visual memory of the reader. 

In a nutshell, I have no doubt that if used as intended, all readers will “ace the boards.” 

Congratulations to this amazing team of authors and editors. 

Happy learning! 

Kamran M. Mirza, MD PhD 

August 2020 - Maywood, IL 


CONTRIBUTORS 


PREFACE 

The first edition of Ace the boards: Neoplastic hematopathology is an attempt to provide residents and 

fellows with a comprehensive, succinct text for hematopathology with ample illustrations. During the COVID 

pandemic, we got innovative with the time available on our hands and created a “Hemepath Book Club.” 

The purpose of this book club was to read and discuss various hematopathology texts virtually with 

residents and fellows across the world. We got an immense response from the residents, fellows, and 

experienced attendings in the field, with comprehensive discussions and amazing learning. The experience 

was truly phenomenal. It was during those sessions, that attendees voiced the need for a one-stop concise, 

easy to read solution for neoplastic hematopathology. There commenced, this incredible journey of evolving 

from writing and compiling notes to becoming book authors. 

It was a challenge to come up with a reference text that would assimilate all the relevant information. We 

made this book in a pointwise format, with pictures, tables, quick revision summaries, and flow cytometry 

plots, and tried to touch all high yield aspects of neoplastic hematopathology. Additionally, we included 

inputs from experts in the field throughout the world, which enriched the text further. 

We sincerely hope that our passion and enthusiasm for the subject will reflect through our book and that 

the readers will find it helpful to read for their board exams and further their hematopathology skills in 

practice. 

We welcome the inputs of our readers as we embark on this journey of learning and hope to incorporate 

their valuable feedback in our future editions. We wish you success in the boards! 

We wish you success in the boards! 

Hemepath Book Club – Authors team. 


CONTENTS 


ACKNOWLEDGEMENT 

We would like to thank God almighty, our families for their love and encouragement, our mentors including 

Dr. Quesada, for their guidance and support and the amazing path twitter community for their 

contributions and feedback. This book would not have been possible without the collective efforts of all of 

the above. We would like to express our gratitude towards Dr. Kamran Mirza for inspiring us to write the 

book and for his constant motivation throughout our journey. 

“I would like to dedicate this book to my parents, Maya Gupta and Jugalkishore Gupta, my loving husband, 

Ashish Gupta, MD and my darling son, Siddharth Gupta.” 

- Akanksha Gupta, MBBS, MD, FASCP 

Memorial Sloan Kettering Cancer Center, NY 

“Dedicated to my beloved husband for always believing in me, and my son for saying, "you must do this for 

you, mommy." 

- Nupur Sharma, MBBS, MD 

East Carolina University, NC 

Ace the Boards: Neoplastic Hematopathology ~ 11 ~

CONTENTS 


CONTENTS 

1.0 

2.0 

2.1 

2.2 

3.0 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

3.10 

3.11 

3.12 

3.13 

3.14 

3.15 

3.16 

3.17 

3.18 

3.19 

3.20 

3.21 

3.22 

3.23 

3.24 

3.25 

3.26 

3.27 


3.29 

3.30 

3.31 

3.32 

3.33 

3.34 

4.0 

The journey of B-lymphocytes: An overview…………………………………………………………………………..………..….17 

Precursor B-cell neoplasms……………………………………………………………………………………………………………….…23 

B-lymphoblastic leukemia/lymphoma, NOS…………………………………………………………………………………….…..25 

B-lymphoblastic leukemia/lymphoma with recurrent genetic abnormalities…………………………………….…27 

Mature B-cell neoplasms………………………………………………………………………………………………………………….….31 

Chronic lymphocytic leukemia/ small lymphocytic lymphoma………………………………………………………….….33 

B-cell prolymphocytic leukemia/lymphoma…………………………………………………………………………………….…..36 

Splenic marginal zone lymphoma…………………………………………………………………………………………….…….……37 

Hairy cell Leukemia……………………………………………………………………………………………………………………….….…40 

Splenic B-cell lymphoma/leukemia, unclassifiable…………………………………………………………………………..…..42 

Lymphoplasmacytic lymphoma…………………………………………………………………………………………………….…....44 

IgM monoclonal gammopathy of undetermined significance…………………………………………………………..….46 

Heavy chain diseases…………………………………………………………………………………………………………………….…….47 

Plasma cell neoplasm……………………………………………………………………………………………………………………..……50 

Extranodal marginal zone lymphoma of mucosa associated lymphoid tissue……………………………….……..63 

Nodal marginal zone lymphoma…………………………………………………………………………………………………….……66 

Follicular lymphoma……………………………………………………………………………………………………………………………68 

Pediatric-type follicular lymphoma…………………………………………………………………………………………….……….73 

Large B-cell lymphoma with IRF4 rearrangement…………………………………………………………………………...…..74 

Primary cutaneous follicle center lymphoma……………………………………………………………………………….………75 

Mantle cell lymphoma……………………………………………………………………………………………………………..….………76 

Diffuse large B-cell Lymphoma, NOS………………………………………………………………………………………….………..79 

T-cell/histiocyte rich large B-cell lymphoma………………………………………………………………………………..….….. 82 

Primary DLBCL of the CNS……………………………………………………………………………………………………………...……83 

Primary cutaneous DLBCL, leg type…………………………………………………………………………………………….……....85 

EBV-positive DLBCL, NOS…………………………………………………………………………………………………………….……...86 

EBV-positive mucocutaneous ulcer……………………………………………………………………………………………….…….87 

DLBCL associated with chronic inflammation……………………………………………………………………………….…..…89 

Lymphomatoid granulomatosis………………………………………………………………………………………….……….……...91 

Primary mediastinal (thymic) large B-cell lymphoma………………………………………………………………….…..…..92 

Intravascular large B-cell Lymphoma………………………………………………………………………………………….………..93 

ALK-positive Large B-cell Lymphoma………………………………………………………………………………………….…..…...94 

Plasmablastic lymphoma…………………………………………………………………………………………………………………….96 

Primary effusion lymphoma………………………………………………………………………………………………………………..97 

HHV8-associated lymphoproliferative disorder………………………………………………………………………….………..99 

Burkitt’s lymphoma………………………………………………………………………………………………………………….……….102 

Burkitt-like lymphoma with 11q aberration.……………………………………………………………………………..……….104 

High grade B-cell Lymphoma……………………………………………………………………………………………………..………105 

B-cell lymphoma, unclassifiable……………………………………………………………………………………………….…….….107 

Journey of T-lymphocytes: an overview…………………………………………………………………………………….….…..109 


5.0 

5.1 

6.0 

6.1 

6.2 

6.3 

6.4 

6.5 

6.6 

6.7 

6.8 

6.9 

6.10 


6.12 

6.13 

6.14 

6.15 

6.16 

6.17 

6.18 

6.19 

7.0 

8.0 

8.1 

8.2 

8.3 

8.4 

8.5 

8.6 

9.0 

10.0 

11.0 







12.0 

Precursor T-cell neoplasms………………………………………………………………………………………………………………..115 

T and NK-lymphoblastic leukemia/lymphoma……………………………………………………………….…………………..117 

Mature T-cell and NK-cell neoplasms………………………………………………………………………………………………...119 

T-cell prolymphocytic leukemia……………………………………………………………………………………..………………....121 

T-cell large granular lymphocytic leukemia…………………………………………………………………..…..………………123 

Chronic lymphoproliferative disorder of NK-cells…………………………………………………………..…………….……125 

Aggressive NK-cell leukemia……………………………………………………………………………………………..…….………...126 

EBV-positive T-cell and NK-cell lymphoproliferative diseases of childhood…………………………...……….….127 

Adult T-cell leukemia/lymphoma…………………………………………………………………………………………………….…132 

Extranodal NK/T-cell lymphoma, nasal type……………………………………………………………………….……………..134 

Intestinal T-cell lymphoma…………………………………………………………………………………………………………….….136 

Subcutaneous panniculitis-like T-cell lymphoma………………………………………………………………………….……140 

Mycosis fungoides……………………………………………………………………………………………………………………….……141 

Sezary Syndrome………………………………………………………………………………………………………………………….…..143 

Hepatosplenic T-cell lymphoma………………………………………………………………………………………………….…….144 

Primary cutaneous CD30-positive T-cell lymphoproliferative disorder……………………………………….……..145 

Primary cutaneous peripheral T-cell lymphomas, rare subtypes…………………………………………………..……147 

Peripheral T-cell lymphoma, NOS…………………………………………………………………………………………..………….148 

Angioimmunoblastic T-cell lymphoma and other nodal lymphomas of TFH origin………………….………….150 

Anaplastic large cell lymphoma, ALK-positive…………………………………………………………………………….……..154 

Anaplastic large cell lymphoma, ALK-negative……………………………………………………………………………….….156 

Breast implant associated large cell lymphoma…………………………………………………………………………….…..158 

Hodgkin lymphoma……………………………………………………………………………………………………………………………159 

Acute myeloid Leukemia and related precursor neoplasms………………………………………………….……………171 

Acute myeloid leukemia with recurrent genetic abnormalities………………………………………….………………173 

Acute myeloid leukemia with myelodysplasia-related changes…………………………………………………….……182 

Therapy related myeloid neoplasms…………………………………………………………………………………………….……184 

Acute myeloid leukemia, NOS……………………………………………………………………………………………………….…..185 

Myeloid sarcoma…………………………………………………………………………………………………………………………….…194 

Myeloid proliferations associated with Down’s Syndrome………………………………………………………………..196 

Acute leukemia of ambiguous lineage…………………………………………………………………………………………….…199 

Blastic plasmacytoid dendritic cell neoplasm…………………………………………………………………………………….205 

Myeloproliferative neoplasms…………………………………………………………………………………………………………..211 

Chronic myeloid leukemia, BCR-ABL1 positive……………………………………………………………………………..…...213 

Chronic neutrophilic leukemia………………………………………………………………………………………………..………...215 

Polycythemia vera……………………………………………………………………………………………………………………..……..217 

Primary myelofibrosis………………………………………………………………………………………………………………..….….219 

Essential thrombocythemia…………………………………………………………………………………………………………….…222 

Chronic eosinophilic leukemia, NOS……………………………………………………………………………………………….….224 

Myelodysplastic syndrome…………………………………………………………………………………………………………….….227 


13.0 

13.1 

13.2 

13.3 

13.4 

13.5 

14.0 

15.0 

16.0 

17.0 

18.0 

19.0 

20.0 

21.0 

22.0 

Myelodysplastic/Myeloproliferative neoplasms…………………………………………………………………………….….239 

Chronic myelomonocytic leukemia……………………………………………………………………………………………….…..241 

Atypical chronic myeloid leukemia, BCR-ABL 1 negative……………………………………………………….…………..243 

Juvenile myelomonocytic leukemia……………………………………………………………………………………….………….245 

Myelodysplasia/Myeloproliferative neoplasm with ring sideroblasts and Thrombocytosis……………..…247 

Myelodysplastic/Myeloproliferative neoplasm, unclassifiable……………………………………………………….….248 

Mastocytosis……………………………………………………………………………………………………………………………….…….251 

Myeloid/lymphoid neoplasms with eosinophilia and gene rearrangements……………………………….……..258 

Myeloid neoplasms with germline predisposition…………………………………………………………………….………..262 

Post-transplant lymphoproliferative disorder……………………………………………………………………………………265 

Other iatrogenic immunodeficiency-associated lymphoproliferative disorders………………………….………267 

Lymphoproliferative diseases associated with primary immune disorders………………………………………..268 

Lymphomas associated with HIV infection……………………………………………………………………………….………..270 

Histiocytic and dendritic cell neoplasms…………………………………………………………………………………….………273 

In a Nutshell………………………………………………………………………………………………………………………………………283 

In a Nutshell [A]- B-cell lymphomas………………………………………………………………………………….………………..285 

In a Nutshell [B]- T-cell lymphomas…………………………………………………………………………………………….……..294 

In a Nutshell [C]- Hodgkin lymphoma…………………………………………………………………………………………..…….297 

In a Nutshell [D]- Acute myeloid leukemia…………………………………………………………………………………………298 

In a Nutshell [E]- Acute leukemia of ambiguous lineage……………………………………………………………….…….302 

In a Nutshell [F]- Other myeloid neoplasms…………………………………………………………………………….…………303 

In a Nutshell [G]- Other high yield topics………….…………………………………………………………………………………307 



Chapter 1: Journey of B-Lymphocyte - An overview 

Kshitija Kale Nupur Sharma Akanksha Gupta 

Chapter 1: Journey of B 

Lymphocyte - An 

Overview 







INTRODUCTION 

• B-cell neoplasms are clonal tumors of B-cells in 

various stages of differentiation 

• The precursor B-cells in bone marrow expresses 

TDT, CD10, and LMO2 

• Pro-B-cell expresses CD34 additionally 

• The pre-B-cell has cytoplasmic µ heavy chains. 

Eventually, it undergoes heavy chain 

rearrangement, following which immature B-cell 

shows membrane IgM expression 

• The light chain gene rearrangement commences 

in the immature B-cells 

• The immature B-cells leave the bone marrow, 

forming mature naïve B-cell (CD5+), which reside 

in the interfollicular area of the lymph node and 

expresses both IgM and IgD 

• Upon antigen exposure, the immature B-cell 

becomes an extra-follicular B-blast cell. These cells 

express IgM 

• The blast cell can either form a short-lived plasma 

cell or can enter the germinal center to undergo 

somatic hyper-mutation and class switch, 

forming centroblasts 

• Centroblasts differentiate into centrocyte in the 

germinal center, which can undergo apoptosis. In 

neoplastic follicles, there is an absence of 

apoptosis thereby leading to BCL2 expression 

• The centrocytes eventually form memory B-cells 

in the marginal zone or a long-lived plasma cell. 

The plasma cell secretes immunoglobulins against 

the antigen exposed 

• The precursor B-cell neoplasms (B-ALL) develop 

from the precursor B-cells; mantle cell lymphoma 

arises from naïve B-cell (CD5 +) 

• The follicular lymphoma, DLBCL (GCB phenotype) 

and Hodgkin lymphoma arise from the germinal 

center B-cells 

• Post germinal center B-cells give rise to MZL, 

MALT lymphoma (memory B-cells), CLL/SLL, DLBCL 

(Non-GCB type) 


Cells of B-cell lineage: 

Centroblasts Centrocytes Marginal zone cells Plasma Cells 

• Reside in the dark zone of 

germinal center 

• Express low levels of 

surface Immunoglobulins 

• Switch off the expression 

of BCL2 (anti-apoptotic): 

thus, prone to apoptosis 

• CD10, BCL6, LMO2, HGAL 

(GCET) are positive 

• IGHV gene and BCL6 

mutation are markers of 

cells that have been 

through germinal center 

• Reside in the light zone of 


• Express higher levels of 

surface immunoglobulins 

• Have somatic 

hypermutations and heavy 

chain class switching, 

thereby differentiating to 

memory B-cells and plasma 

cells 

• IRF4 (MUM1) 

downregulates BCL6 

expression 

• Thus, late centrocytes (along 

with plasma cells) are BCL6 

negative, IRF4 (MUM1) 

positive 

• Post-germinal center 

memory B-cells 

• Reside in marginal 

zones of lymph 

nodes, spleen, and 

mucosa-associated 

lymphoid tissue 

• Express Pan-B-cell 

antigens and surface 

IgM (with only low 

levels of IgD) 

• Lack of both CD5 and 

CD10 

• Express BCL2, HLA-DR 

• Enter the peripheral 

blood from the 


• Have mutated IGHV 

status 

• Predominantly IgG, 

IgA positive 

• Lack of surface Ig and 

CD20 

• IRF4(MUM1) positive 

• CD79a, CD38, CD138 

positive 

• CyclinD1 positive 

B-CELL Ig MATURATION 

Determinants of Ig molecules 

Isotype: 

• Distinguish among classes of antibodies 

• Species-specific 

• Due to the amino acid sequences of the VH and VL 

portions. 

Each chain (heavy and light) has two regions: 

2 regions 

Isotypes 

Constant region 

- limited amino acid 

sequence variability 

Variable region 

- extensive sequence variability 

- forms idiotype 

Heavy Chain isotype 

G, M, A, D, E 

Light chain isotype 

, 

Allotype: 

• Distinguish between amino acid sequences of Ig 

• Individual specific 

• Due to small differences (one to four amino acids) 

that affect the CH and CL regions. 

Idiotype: 

• Attributed to unique antigen-binding structure 

• Clone specific 

• Normal B-cell differentiation begins with B 

lymphoblasts, which undergo Immunoglobulin VDJ 

gene rearrangement 

• The two types of gene segments that encode the lightchain 

V region are called variable (V) and joining (J) 

gene segments 

• The heavy-chain locus includes an additional set of 

diversity (D) gene segments that lie between the 

arrays of V and J gene segment 


• The variable region consists of V, D, and J regions on 

the heavy chain and V and J region on the light chain 

• The constant region comprises of CH1, CH2, and CH3 

• On exposure to antigen, a class switch occurs in the 

variable region 

• Genes rearrangements are responsible for 

Immunoglobulin variable region 

Heavy chain 

VDJ gene rearrangements 

Light Chain 

VJ gene rearrangements 

Chr 14 

Chr 2 Chr 22 

*CDR: Complementarity determining region 


Chapter 2.1: B Lymphoblastic Leukemia/Lymphoma, NOS 

Nupur Sharma Kshitija Kale Akanksha Gupta 




Chapter 2: Precursor B- 

cell Neoplasms 






INTRODUCTION 

● Neoplasm of precursor lymphoid cells committed 

to the B-cell lineage 

● Composed of small to medium-sized blast cells 

with scant cytoplasm, moderately condensed to 

dispersed chromatin, and inconspicuous nucleoli 

● Involves bone marrow and blood (B-ALL) and 

occasionally presents with primary involvement of 

nodal or extranodal sites (B-LBL) 

● When the process is confined to a mass lesion 

with no or minimal evidence of blood and marrow 

involvement, it is termed as lymphoblastic 

lymphoma (LBL) 

● No agreed-upon lower limit for the proportion of 

blasts required to establish a diagnosis of 

lymphoblastic leukemia (ALL) 

● In general, the diagnosis should be avoided when 

there are < 20% blasts 

● In many treatment protocols, a value of > 25% 

marrow blasts is used to define leukemia 

Demographics 

● Primarily a disease of children 

● Increased risk of B-ALL in children with Down 

syndrome and other constitutional genetic 

disorders, ionizing radiation and occupational 

exposure 

● Increased risk of B-ALL associated with certain 

single nucleotide polymorphisms (SNPs) of genes 

including GATA3, ARID58, IKZF1, CEBPE, and 

CDKN2A/B 

Sites of Involvement 

● B-ALL: Blood, bone marrow, central nervous 

system (CNS), lymph nodes, spleen, liver, and 

testes 

● LBL: Skin, soft tissue, bone, and lymph nodes 

Clinical presentation 

● Bone marrow failure: thrombocytopenia, anemia, 

and/or neutropenia 

● Lymphadenopathy, hepatomegaly, and 

splenomegaly are frequent 

● Bone pain and arthralgias 


MORPHOLOGY AND PHENOTYPE 

Peripheral Smear 

● Blasts: Vary from small blasts with scant cytoplasm, 

condensed nuclear chromatin, and indistinct 

nucleoli to larger cells with moderate amounts of 

light blue to bluish-grey cytoplasm (occasionally 

vacuolated), dispersed nuclear chromatin, and 

multiple variably prominent nucleoli 

● Nuclei are round or show convolutions 

● Lymphoblasts have cytoplasmic pseudopods 

(hand-mirror cells) 

Bone Marrow 

● Normal B-cell precursors (hematogones) can mimic 

lymphoblasts, but they have even higher nuclear: 

cytoplasmic ratios, more homogeneous 

chromatin, and no nucleoli 

● Lymphoblasts in B-ALL are relatively uniform in 

appearance, with round to oval, indented, or 

convoluted nuclei and finely dispersed chromatin. 

Nucleoli range from inconspicuous to prominent 

(Fig 1) 

● Bone marrow biopsy shows an increase in blasts, 

sometimes in sheets (Fig 2) 

Other organs 

● LBL is generally characterized by a diffuse or (less 

commonly) paracortical pattern of involvement of 

lymph nodes 

● A single-file pattern of infiltration of soft tissue is 

common 

Figure 1 


Fig 4 

Figure 2 

Immunophenotype 

● Positive: CD19, cyCD79a, and cyCD22, CD10, 

surface CD22, CD24, PAX5, and TdT (Fig 3) 

● Myeloid antigens CD13, CD33 may be expressed 

● CD34: variable. CD45 is usually negative or dim 

(Fig 4) 

● Surface immunoglobulins absent (not shown) 

● Hematogones show a continuum of expression 

of markers of B-cell maturation, including 

surface immunoglobulin light chain, and display 

a reproducible pattern of acquisition and loss of 

normal antigens 

● B-ALL shows expression that differs from 

normal, with either overexpression or underexpression 

of many markers, including CD10, 

CD45, CD38, CD58, and TdT (Fig 3 and 4) 

Fig 4: Flow cytometry, bone marrow aspirate. Blasts, in this case, 

show no CD45, bright CD34, CD19, CD10, partial CD13 and CD33, 

dim CD38 and CD20 

● Caveat: CD79a is not specific (seen in T-ALL) 

● Earliest stage (early precursor B-ALL or pro-B 

ALL): Blasts express CD19, cyCD79a, cyCD22, and 

nuclear TdT 

● Intermediate stage (common B-ALL): Blasts 

express CD10 

● Most Mature precursor B-cell differentiation 

stages include pre-B ALL: Blasts express 

cytoplasmic mu chain 

GENETICS 

● Clonal rearrangements of IGH 

● T-cell receptor (TR) gene rearrangements in 

many cases 

● PAX5 mutation seen in most subtypes of B-ALL 

PROGNOSIS 

● Good prognosis: Children 

● Poor prognosis: Infancy, older patient age, 

higher white blood cell count, slow response to 

initial therapy, presence of CNS disease at 

diagnosis and the presence of minimal residual 

disease after therapy 

Fig 3: TdT 


Chapter 2.2: B Lymphoblastic Leukemia/Lymphoma with 

Recurrent Genetic Abnormalities 


INTRODUCTION 

● Group of diseases characterized by recurrent 

genetic abnormalities, including balanced 

translocations and abnormalities involving 

chromosome number 

B LYMPHOBLASTIC LEUKEMIA/ LYMPHOMA WITH 

t(9;22) (q34.1; q11.2); BCR-ABL1 

INTRODUCTION 


● More common in adults 


● Marrow replaced by lymphoblasts 


● Positive: CD10, CD19, CD34, TDT, CD25 and 

myeloid markers CD13, CD33, CD65+, CD66c+ 

● Negative: CD117 

GENETICS 

● p190 BCR-ABL1 fusion protein in childhood 

cases 

● p210 BCR-ABL1 fusion protein in about half of 

the adult cases, remainder adult cases have 

p190 

PROGNOSIS 

● Worst prognosis 

● Favorable prognostic factors in children: 

younger age, low TLC, response to therapy 

B LYMPHOBLASTIC / LYMPHOMA WITH t(v; 

11q23.3); KMT2A-REARRANGED 

INTRODUCTION 

● t(4;11) most common amongst 11q23 

alterations 


● Infants 100 x 10 9 / L 

● High frequency of CNS involvement 




● Positive: CD19, CD15 

● Negative: CD10, CD24 

● NG2 homolog encoded by CSPG4 is specific 

GENETICS (Table 1) 

Table 1: 

KMT2A-rearranged neoplasms 

Chromosome Gene Fusion Neoplasm 

product 

4q21 AF4 KMT2A-AF4 Most common 

in B ALL 

19p13 

MLLT1 

(ENL) 

KMT2A- 

MLLT1 

Common in 

T-ALL 

9p21.3 MLLT3 

(AF9) 

KMT2A- 

MLLT3 

Common in 

AML 

Others: t(11,19), t(9,11), t(11q23; V) and del(11q23) 

PROGNOSIS 

● Poor, particularly in infants 


t(12;21) (p13.2; q22.1): ETV6-RUNX1 (TEL-AML1) 

INTRODUCTION 

● More common in children 




● Positive: CD10, CD19, CD34, myeloid marker CD13 

● Negative: CD20, CD9, CD66c 

GENETICS 

● Fusion protein interferes with the normal function 

of transcription factor RUNX1 is an early lesion in 

leukemogenesis 

PROGNOSIS 

● Favorable prognosis with a high cure rate 

● Less favorable factors: age >10 years, high 

leukocyte count 



HYPODIPLOIDY 

INTRODUCTION 


● Seen in both children and adults 


Microscopy 

Marrow replaced by lymphoblasts 



GENETICS 

● Loss of one or more chromosomes 

● Refer to Table 2 

Table 2: Genetic profile of B-ALL with hypodiploidy 

Subtypes 

Number of 

chromosomes 

Features 

Near haploid 23 – 29 RAS or TK mutations 

Worst prognosis 

Low 

hypodiploid 

High 

hypodiploid 

Near diploid 44 - 45 

33 – 39 Loss of function 

mutations in P53, 

RB1 

If germline P53 

mutations: Li- 

Fraumeni + 

40 – 43 

PROGNOSIS 

• Poor (irrespective of MRD status) 


t(5;14) (q31.1; q32.1): IGH/IL3 

INTRODUCTION 


● Rare, seen in both children and adults, M>F 

● Present with asymptomatic eosinophilia 

● May present with cutaneous erythematous 

rash, neurological alterations, lung involvement 

and cardiac involvement 


Microscopy 

● Blasts can be deceptively absent in peripheral 

blood 

● Increase in reactive circulating eosinophils and 

lymphoblasts 



GENETICS 

● The fusion of IGH and IL3 causes constitutive 

overexpression of IL3 

PROGNOSIS 

● Poor 


t(1;19) (q23; p13.3) : TCF3-PBX1 

INTRODUCTION 


● More common in children (adults have better 

prognosis) 

● Non-CNS extramedullary involvement 


Microscopy: similar to other B-ALL 


● Pre-B phenotyping: CD19, CD10, cytoplasmic µ 

heavy chains 

● CD9 strong expression 

● CD34 absent 

GENETICS 

● Fusion protein acts as a transcriptional activator 

● Alternative TCF3 translocation t(17;19) TCF3- 

HLF: Dismal prognosis 

PROGNOSIS 

● Poor prognosis, risk of CNS relapse 

Ace the Boards: Neoplastic Hematopathology ~ 28 ~

B LYMPHOBLASTIC LEUKEMIA/ LYMPHOMA BCR 

ABL1 – LIKE 

PROGNOSIS 

● Relatively poor prognosis 

INTRODUCTION 


● Common, affects adolescents and adults 

● Children with Down Syndrome: high frequency 

of B-ALL with CRLF2 translocations 


● CD19, CD10, CD22 positive 

● CRLF2 expressed at high levels 

GENETICS 

● The most common mutations target JAK2, JAK1, 

IL-7-R, and CRLF2 

● Associated with interstitial deletion of the PAR1 

gene (Xp22.3 or Yp11.3) 

● IGH translocations involving EPOR 

● Tyrosine kinase- type translocations 

● ABL1 with kinases other than BCR 

● Deletions and mutations in IKZF1 and 

CDKN2A/B (have a role in leukemogenesis) 

PROGNOSIS 

● Poor prognosis, especially with CRLF2 

translocations 

● Dramatic response to TK inhibitors 

B LYMPHOBLASTIC LEUKEMIA/ LYMPHOMA with 

iAMP21 

INTRODUCTION 


● More common in older children with low 

leukocyte count 

GENETICS 

● Amplification of portion of chromosome 21 

● Five or more copies of the gene or three or 

more copies of abnormal chromosome 

● Other abnormalities: Gain of chromosome X, 

abnormality of chromosome 8 

● Deletion of RB1 and ETV6, rearrangement of 

CRLF2 


OVERVIEW OF B LYMPHOBLASTIC LEUKEMIA / LYMPHOMA WITH RECURRENT GENETIC ABNORMALITIES 

B ALL with 

recurrent 

genetic 

abnormalities 

Age group 

Clinical 

features 

Immunophen 

otyping 

Markers 

expressed 

Absent 

expression 

t(9;22) 

BCR-ABL 

1 

Adults 

mainly 

CD10 

CD19 

TDT 

CD13 

CD33 

CD25 

CD66c 

CD34 

CD117 

Genetics t (9;22) 

BCR-ABL 

1 

p190: 

children 

p210: 

adults 

(50 %) 

p190: 

adults 

(50%) 

Diagnosis 

t(v;11q) 

KMT2A 

rearrangeme 

nts 

Less than 1 yr 

Adults 

High TLC (> 

100 x 10 9 /L) 

CNS involved 

CD19 

CD15 (pro B) 

CSPG4 

(characteristi 

c and 

relatively 

specific); 

CD10 neg 

CD10 

CD24 

1.KMT2A on 

11q23.2 is 

rearranged in 

utero 

2.Many 

fusion 

partners 

3. Commonly, 

t(4,11): fuses 

with AF4 on 

chr.4q 

4.Associated 

with FLT3 

t(12;21) 

ETV6- 

RUNX1 

B-ALL/LBL 

With 

Hyperdiploidy 

B-ALL/LBL 

With 

hypodiploidy 

t(5;14) 

IGH-IL3 

Children Children Children and adults Children and 

adults 

CD10 

CD19 

CD34 

CD13 

TDT 

CD66c 

CD9 

CD20 

Fusion 

protein 

interferes 

with the 

function 

of RUNX1 

Fusion 

probes 

CD10 

CD19 

CD34 

TDT 

CD45 

1. >50 

chromosome 

s 

2. Commonly 

Chr 

4/14/21/X 

are extra 

2. No 

structural 

abnormalities 

3. Can be just 

endoreduplication 

of 

hypodiploid 

mimicking 

hyperdiploid 

Karyotyping 

FISH 

FCM DNA 

index 

Prognosis Worst Poor Favorable Very 

favorable 

Prognostic 

factors 

Favorable 

: younger 

age, low 

TLC, 

response 

to 

Therapy 

Adverse: 

Age < 6 

months 

Adverse: 

Age > 10 

years 

High TLC 

CD19 

CD10 

TDT 

CD34 

< 46 chromosomes, 

FCM DNA index < 1.0 

23-29 Near 

haploid 

RAS/ TK 

mutations 

Worst 

prognosis 

33-39 Low hypo 

diploid 

Loss of 

function of 

p53, RB1 

40-43 High hypo 

diploid 

44-45 Near 

diploid 

t(1;19) 

TCF3-PBX1 

Children 

B-ALL/LBL 

BCR-ABL1 - 

like 

Adolescent 

s and 

adults 

Eosinophilia CNS relapse In Down 

syndrome 

children. 

High TLC. 

CD19 

CD10 

TDT 

CD34 

IGH – IL3 

rearrangeme 

nt causes 

constitutiona 

l 

overexpressi 

on of IL-3 

Pre-B 

phenotype 

CD19 

CD10 

Cytoplasmic 

µ heavy 

chain 

CD9, TDT 

CD34 

TCF3- PBX1 

fusion 

causes 

transcriptio 

n activation 

TCF3-HLF: 

dismal 

prognosis 

CD10 

CD19 

CRLF2 

TDT 

CD34 

CRLF2 

rearrange 

ment. 

IGH 

translocati 

on of 

ABL1 with 

kinases 

other than 

BCR 

B ALL, 

iAMP21 

Poor Poor Poor Poor 

Treatment TKI Intensive 

chemothera 

py 

CRLF2: 

poorer 

prognosis 

TKI 

Older Children 

Low TLC 

Robertsonian 

t(15;21) 

Unknown 

Amplification of 

portion of Chr 

21 

Five or more 

copies of 

RUNX1 gene 

OR 

3 or more 

copies of a 

single abnormal 

chromosome 

FISH probe for 

RUNX1 


Chapter 3: Mature B-cell 

Neoplasms 


Chapter 3.1: Chronic Lymphocytic Leukemia/Lymphoma 

(CLL) 

Nidhi Kataria 



Chapter 3.1: Chronic Lymphocytic Leukemia/Lymphoma 

(CLL) 

INTRODUCTION 

● Neoplasm of monomorphic small mature B-cells 

that co-express CD5 and CD23 

● Requires presence of monoclonal B-cell count ≥5 

x 10 9 /L, with the characteristic morphology and 

phenotype of CLL in the peripheral blood 

Demographics 

● Adults, males 


● Blood, bone marrow and secondary lymphoid 

tissues such as the spleen, lymph nodes, and 

Waldeyer ring 

● Extranodal involvement (e.g. of the skin, GI tract, 

or CNS) in some cases 


● Diagnosed on routine complete blood count in 

asymptomatic people 

● Lymphadenopathy, splenomegaly, anemia, or 

thrombocytopenia in some cases 

● Autoimmune cytopenia (i.e., autoimmune 

hemolytic anemia, immune thrombocytopenia, or 

erythroblastopenia) 

● A small paraprotein, usually of lgM type, can be 

observed in a few patients 

● Hypo-gammaglobulinemia 


Lymph Node 

● Diffuse architectural effacement by a 

proliferation of small lymphocytes with variably 

prominent paler proliferation centers (pseudofollicles) 

(Fig 1) 

Figure 1 

Nidhi Kataria 


● Nodal involvement can also be interfollicular or 

perifollicular 

● The predominant cell is a small lymphocyte with 

scant cytoplasm, round nucleus with clumped 

chromatin, and occasionally a small nucleolus 

● The proliferation centers are composed of small 

lymphocytes, prolymphocytes, and paraimmunoblasts 

(Fig 2) 

Figure 2 

Fig 3: CD20 

● Prolymphocytes are small to medium-sized cells 

with relatively clumped chromatin and small 

nucleoli 

● Para-immunoblasts are larger cells with round to 

oval nuclei, dispersed chromatin, central 

eosinophilic nucleoli, and slightly basophilic 

cytoplasm 

● Large proliferation centers associated with 

increased proliferation, deletion in 17p13, trisomy 

12, and a more aggressive course compared to 

cases with smaller proliferation center 



● CLL cells are small lymphocytes with clumped 

chromatin and scant cytoplasm 

● Can show prolymphocytes (cells with irregular 

nuclear contours, and larger cells with more 

dispersed chromatin and more abundant 

cytoplasm) they constitute 55% prolymphocytes: B-cell Prolymphocytic 

leukemia 

Bone Marrow 

● Interstitial, nodular, mixed (nodular and 

interstitial), or diffuse involvement 

● Diffuse involvement associated with more 

advanced disease (Fig 4) 

● Para-trabecular aggregates are not typical 

● Most cases have >30% CLL cells in the bone 

marrow aspirate 

Fig 5:CD20 

Figure 6 

Figure 4 

Spleen 

● White pulp involvement prominent, but red 

pulp also involved 

● Proliferation centers are less common than in 

lymph nodes 


● Positive: Circulating leukemic B-cells express 

CD19 and dim surface lgM/IgD, dim CD20 (Fig 3 

and Fig 5), dim CD22, and dim CD79b. 

● Positive for CD5, CD43, CD23, CD200, LEF1 

● Negative: CD10 and FMC7, BCL6 (Fig 6) 

● Atypical immunophenotype (e.g., CD5-, CD23-, 

FMC7+, strong surface immunoglobulin, or 

CD79b+) can be seen, and other lymphomas 

(SMZL) should be excluded 

● In tissue sections, cytoplasmic immunoglobulin 

may be positive 

● CD20 and CD23 expression is stronger in cells of 

the proliferation centers than in diffuse areas 

● LEF1+ is used to identify infiltration in tissues 

GENETICS 

● The most common alterations are deletion in 

13q14.3 and trisomy 12 or partial trisomy 12q13 

● Less commonly, there is a deletion in 11q22-23 

(ATM and BIRC3), 17p13 (TP53), or 6q21 


● Commonly mutated genes are NOTCH1, SF3B1, 

TP53, ATM, BIRC3, POT1 and MYD88 

● Three epigenetic subgroups of CLL: 

Naïve-like, intermediate and memory-like 

‣ Naïve-like CLLs have mainly unmutated IGHV 

genes 

‣ Intermediate and memory-like CLLs have 

mutated IGHV genes 

● Clinical behavior in terms of aggression: 

Naïve (worse)> Intermediate> Memory 

PROGNOSIS AND TREATMENT 

Prognostic Indolent Intermediate Aggressive 

indicator 

IgVH Mutated Intermediate Unmutated 

B2M Less than 

2 mg/L 

Between 2 

and 4 mg/L 

More than 4 

mg/L 

FISH 13q14 

deletion 

Trisomy 12 11q 

deletion, 

17p 

deletion 

ZAP70 Less than 

20% 

More than 

20% 

CD38 Less than 

30% 

More than 

30% 

● Expression of ZAP70, CD38, and CD49d is 

associated with worse prognosis 

● Other adverse prognostic factors include a rapid 

lymphocyte doubling time in the blood ( 40% or increased 

mitoses in the proliferation centers 

● Pro-lymphocytic transformation: Increased 

prolymphocytes in the blood 

● However, the progression of CLL into B-cell 

prolymphocytic leukemia does not occur 

● Richter syndrome: Can be DLBCL type and classic 

Hodgkin lymphoma type 

● DLBCL type Richter syndrome: 

‣ Clonally related to the previous CLL: IGHVunmutated, 

median survival time < 1 year 

‣ Clonally unrelated cases: IGHV-mutated 

(prognosis as de novo DLBCL) 

● DLBCL transformation is associated with TP53 and 

NOTCH1 mutations, CDKN2A deletions, 

and MYC translocations 

● Hodgkin lymphoma: Most cases occur in mutated 

CLL, (clonally unrelated) and are EBV-positive 

● The diagnosis of Hodgkin lymphoma in the setting 

of CLL requires classic Reed- Sternberg cells in an 

appropriate background 

● The presence of scattered EBV-positive Reed- 

Sternberg cells in the background of CLL does not 

fulfill the criteria for the diagnosis of Hodgkin 

lymphoma 

● It should be noted that EBV-associated 

lymphoproliferative disorders, including Hodgkin 

lymphoma-type proliferations, may occur in patients 

with CLL following immunosuppressive therapy 

MONOCLONAL B―CELL LYMPHOCYTOSIS 

● Monoclonal B-cell count

Chapter 3.2: B - Prolymphocytic Leukemia (B-PLL) 

INTRODUCTION 

● Neoplasm of B-cell prolymphocytes affecting the 

peripheral blood, bone marrow, and spleen 

● Prolymphocytes must constitute > 55% of 

lymphoid cells in peripheral blood 

● Diagnoses to exclude: 

‣ Pleomorphic mantle cell lymphoma 

{cyclinD1, SOX11, t(11;14)} 

‣ Splenic marginal zone lymphoma, and 

‣ CLL with an increased number of 

prolymphocytes 

Demographics 

● Extremely rare and affects elderly 


● Peripheral blood, bone marrow, and spleen 


● B symptoms, massive splenomegaly 

● Minimal peripheral lymphadenopathy, and 

rapidly increasing lymphocyte count 

>100,000/microliter 

● Anemia and thrombocytopenia 


Peripheral blood 

● Most circulating cells are prolymphocytes 

● Prolymphocytes: Medium-sized lymphoid cells 

(twice the size of a normal lymphocyte) with a 

round nucleus (rarely indented nucleus), 

moderately condensed nuclear chromatin, a 

prominent central nucleolus, and a relatively 

small amount of faintly basophilic cytoplasm 

Bone marrow 

● Interstitial or nodular intertrabecular infiltration 

of lymphoid cells 

Spleen 

● Expanded white pulp nodules and red pulp 

infiltration by intermediate to large cells with 

abundant cytoplasm and irregular or round nuclei 

with a central eosinophilic nucleolus 

Lymph node 

● Diffuse or vaguely nodular infiltration by similarlooking 

cells 

● Proliferation centers (pseudofollicles) not seen 

Nidhi Kataria Nupur Sharma Akanksha Gupta 


● Positive: bright surface IgM/lgD, as well as bright 

for B-cell antigens (CD19, CD20, CD22, CD79a, 

CD79B), and FMC7 

● CD5, CD23 usually negative, may express rarely 

(

Chapter 3.3: Splenic Marginal Zone Lymphoma (SMZL) 

INTRODUCTION 

● B-cell neoplasm composed of small lymphocytes 

that: 

‣ Surrounds and replace the splenic white pulp 

germinal centers 

‣ Efface the follicle mantle, and merge with a 

peripheral (marginal) zone of larger cells, 

admixed with scattered transformed blasts 

‣ Both small and larger cells infiltrate the red 

pulp 

● Splenic hilar lymph nodes and bone marrow are 

often involved 

● Lymphoma cells are frequently found in the 

peripheral blood as villous lymphocytes 

Demographics 

● Rare, >50 years, M=F 


● Spleen, splenic hilar lymph nodes, bone marrow, 

liver, and the peripheral blood 

● Peripheral lymph nodes are not typically involved 

Clinical Presentation 

● Splenomegaly 

● Autoimmune thrombocytopenia or anemia 

● A variable presence of peripheral blood villous 

lymphocytes 

● Peripheral lymphadenopathy and extranodal 

infiltration are extremely uncommon 

● About one-third of patients have a small 

paraprotein, but marked hyperviscosity and 

hypergammaglobulinemia are uncommon 

● An association with hepatitis C has been 

described 


Macroscopy 

● Gross examination of the spleen reveals a 

marked expansion of the white pulp and 

infiltration of the red pulp 

Microscopy 

Spleen 

White pulp 

● A central zone of small round lymphocytes 

surrounds or replaces reactive germinal 


centers, with effacement of the normal follicle 

mantle (Fig 1) 

● The central zone merges with a peripheral paler 

zone of small to medium-sized cells with more 

dispersed chromatin and abundant pale 

cytoplasm, which resemble marginal zone cells, 

with admixed interspersed transformed blasts 

(Fig 2) 

Figure 1 

Figure 2 

Red pulp 

● Infiltrated, with small nodules of the larger cells 

and sheets of the small lymphocytes, which often 

invade sinuses 

Variations 

● Epithelioid histiocytes may be present in the 

lymphoid aggregates 

● Markedly predominant population of the larger 

marginal zone-like cells 

● Plasmacytoid differentiation may occur 

Splenic hilar lymph nodes 


● Nodular proliferation with preservation of the 

dilated sinuses 

● Lymphoma surrounds and replaces germinal 

centers, but the two cell types, small 

lymphocytes, and marginal zone cells, are often 

more intimately admixed, without the formation 

of a distinct paler so-called marginal zone 

Bone marrow 

● Nodular interstitial infiltrates are cytologically 

similar to that in the lymph nodes 

● Sinusoidal involvement, more apparent after 

CD20 immunostaining 


● Lymphoid cells have short polar villi (Fig 3) 

● Some may appear plasmacytoid 

Fig 5: CD20 

● The tumor cells are positive for CD20 (Fig 5), CD79a, 

CD19, CD22, PAX5 

● They express surface lgM and usually IgD 

● Negative for CD5, CD10, CD23, CD43, annexin A1, 

CD103, cyclin D1 

● Ki67 staining shows a distinctive targetoid pattern 

due to an increased growth fraction in both the 

germinal center, if present, and the marginal zone 

● A group of CD5+ SMZL cases has been described, 

distinguished by a higher lymphocytosis and 

diffuse bone marrow infiltration 

Picture credits: Deniz Peker, MD @Hemepathgal 


Fig 3 

DIFFERENTIAL DIAGNOSIS 

● Chronic lymphocytic leukemia: Positive for CD5, 

CD23, LEF1, CD200 

● Hairy cell leukemia: The nodular pattern on bone 

marrow biopsy excludes HCL {Positive for 

AnnexinA1 etc.} 

● Mantle cell lymphoma: Positive for CD5, cyclin 

D1, SOX11, t(11,14) 

● Follicular lymphoma: Positive for CD10, BCL6, 

BCL2 

● Lymphoplasmacytic lymphoma: MYD88 mutation 

Fig 4: CD3 

● CD3 highlights the normal T-cell component in the 

periarteriolar lymphoid sheaths (Fig 4) 

GENETICS 

Antigen receptor genes 

● IG heavy and light chain genes have clonal 

rearrangements and somatic hypermutation 

● Bias in IGHV1-2*04 usage has been found in a 

few cases 


● SMZL lacks recurrent chromosomal 

translocations, unlike other lymphoma types, for 

example, 

1. t(14;18) (q32;q21) translocation affecting 

BCL2 in follicular lymphoma 

2. t(11;14) (q13;q32) translocation affecting 

CCND1 in mantle cell lymphoma 

3. t(11;18), t(14;18) and t(1;14) in MALT 

lymphoma 

● A small number of SMZLs carry a recurrent t(2;7), 

which activates the CDK6 gene through 

juxtaposition with the IGK locus 

● Few SMZLs show a heterozygous deletion in 7q, 

that is rarely seen in other lymphomas 

● A gain of 3q is present in many cases 

● NOTCH2 and KLF2 are commonly mutated genes, 

often associated with a deletion in 7q 


● The clinical course is indolent 

● Poor response to chemotherapy that is typically 

effective in other small B-cell neoplasms 

● Patients generally have good hematological 

responses to splenectomy and rituximab, with 

long-term survival 

● Hepatitis C virus-positive cases respond to 

antiviral treatment using interferon-gamma, with 

or without ribavirin 

● Adverse clinical prognostic factors include a 

1. Large tumor mass and 

2. Poor general health status 

3. NOTCH2 and KLF2; and TP53 mutations 

4. Mutations in NOTCH2, MAP2K1, BRAF, SF3B1, 

and p53: short survival 

● The clinical scoring system incorporates 

hemoglobin concentration, platelet count, LDH 

level, and presence of extra hilar 

lymphadenopathy 

● Transformation to large B-cell lymphoma occurs in a 

few cases 


Chapter 3.4: Hairy Cell Leukemia (HCL) 

INTRODUCTION 

● Indolent neoplasm of small mature lymphoid 

cells with ovoid nuclei and abundant cytoplasm 

with hairy projections involving peripheral 

blood, bone marrow, and splenic red pulp 

Demographics 

● Rare 

● Common in middle-aged to elderly 

● Male predominance 

Etiology 

● BRAF V600E mutation in all cases 

● Leads to constitutive activation of MAPK 


● Commonly bone marrow and spleen 

● Peripheral blood circulating cells seen 

● Liver, lymph node and the skin may be involved 


● Weakness, fatigue, left upper quadrant pain, 

fever, bleeding 

● Splenomegaly, pancytopenia, especially 

monocytopenia 

● Hepatomegaly, recurrent infections, immune 

dysfunction 

Nupur Sharma 


● Cytoplasm pale blue, abundant with hairy 

projections on the edges and may contain 

vacuoles/ rod-like inclusions 

Bone marrow 

● Diagnosis best made on bone marrow biopsy (Fig 

2, 5, and 6) 

● Increase in reticulin fibers leads to dry tap on 

aspiration 

● Interstitial or patchy involvement with some 

preservation of fat or other hematopoietic 

elements 

● Infiltrate consists of widely spaced lymphoid 

cells (closely packed nuclei in other indolent 

lymphomas) 

● Abundant cytoplasm and prominent borders 

give a fried egg appearance (Fig 2) 


● Grossly, splenomegaly with a diffuse expansion of 

red pulp with blood lakes 


● Hairy cells (Figure 1): Small to medium-sized cells 

with a kidney-shaped nucleus, inconspicuous 

nucleoli, and spongy ground glass chromatin, less 

clumped than normal lymphocyte 

Credits: Fernando Martin Moro, @Fer_martinmoro 

Figure 1 

Figure 2 

● In cases with hypocellular bone marrow, 

perform immunostaining for B-cell antigens 

(CD20) to avoid misdiagnosing as aplastic 

anemia 

Spleen 

● Infiltrates in the red pulp, white pulp atrophic 

● Blood lakes (red blood cells surrounded by 

hairy cells) due to disruption of normal blood 

flow in the red pulp 

Other organs 

● Other organs like liver, lymph nodes, spleen, or 

other extramedullary involvement (Fig 3, Fig 4) 

can be seen 


Figure 3 

Fig 5: Annexin A1 

Fig 6: BRAF 

Figure 4 

Cytochemistry 

● Tartrate resistant acid phosphatase positive 


● Positive: bright co expression of CD20, CD22 and 

CD11C and expression of CD103, CD25, CD123, 

TBX21 (TBET), Annexin A1 (most specific, Fig 4,5), 

FMC7, CD200 and cyclinD1 

● Negative: CD5 and CD10 (rare cases may be 

positive) 

● Minimal residual disease best assessed by 

multicolor flow cytometry targeting HCL profile or 

immunostaining for TBX21 (TBET), BRAFV600 E 

(Fig 6) protein 

GENETICS 

● BRAF V600E mutation 

● IGHV genes with somatic hypermutation seen in 

most cases indicates isotope switch arrest 


● Most cases respond to interferon alfa or 

nucleosides. Relapse is treated with rituximab, anti 

CD22 agents or BRAF inhibitors 

Characteristic HCL (classic) SMZL 

Nucleus 

Oval, sometimes Round 

“coffee bean” 

Cell surface Circumferential 

projections 

Noncircumferential 

polar projections 

BM infiltration 

pattern 

Splenic 

infiltration 

pattern 

Diffuse and/or 

interstitial 

Red pulp, with 

effacement 

of white pulp 

Nodular and/or 

intrasinusoidal 

White pulp 

CD123, BRAF Positive 

Negative 

V600E, 

AnnexinA1 

Table courtesy: Dr. Anju Pandey, MBBS, MD 


Splenic B-cell 

Lymphoma/Leukemia, 

Unclassifiable 

Chapter 3.5: Splenic B-cell Lymphoma/Leukemia, 

Unclassifiable 

Splenic diffuse red pulp 

small B-cell lymphoma 

(SDRPL) 

Hairy cell leukemia 

variant 

SPLENIC DIFFUSE RED PULP SMALL B-CELL LYMPHOMA 

INTRODUCTION 

● Diffuse involvement of splenic red pulp by small 

monomorphous B-lymphocytes 

● Rare, age > 40 years 

• PS: Villous lymphocytes 

• BM: Pure intra-sinusoidal B lymphocytes 

• Spleen: Diffuse red pulp involvement 


● Low lymphocytosis +/- thrombocytopenia, 

leukopenia, massive splenomegaly 


Peripheral smear 

● Lymphocytosis, villous lymphocytes are seen 

Bone Marrow 

● Intra-sinusoidal infiltration +/- interstitial or 

nodular infiltration 

● No evidence of lymphoid follicles 

Spleen 

Red pulp 

● Diffuse involvement 

● Blood lakes are lined by leukemic cells 

● Cells: Small to medium-sized, monomorphic 

● Nuclei: Round and regular, compact chromatin, 

distinct small nucleolus 

● Cytoplasm: Pale, plasmacytoid (however, Ig and 

CD38 is absent) 

White pulp 

● Inconspicuous 

Cytochemistry: TRAP negative 

Immunophenotyping 

● Positive: CD20, CD72 (DBA44), IgG. Rarely, IgM 

/CD103/CD11c can be positive 


● Negative: IgD, Annexin A1, CD25, CD5, CD103, 

CD123, CD11c, CD10, CD23 

GENETICS 

● Somatic hypermutation in IGHV gene 

● Overrepresentation of IGHV 3-23, IGHV 4-34 

Cytogenetic alterations 

● t(9;14) – involves PAX5, IGH genes. No evidence 

of CCND 1 rearrangements, del 7q, trisomy 3/18 

● Majority of cases have an abnormality in copy 

number arrays 

Sequencing: Increased expression of cyclin D3 

● Recurrent mutations in the CCND3 PEST domain 

● Infrequent mutations in NOTCH1, MAP2K1, BRAF 

● SF3B1, TP53: Have short survival 


● Good response after splenectomy 

● Mutations in NOTCH1, MAP2K1, BRAF, SF3B1, 

p53: have short survival 

HAIRY CELL LEUKEMIA VARIANT (HCLv) 

• Marked leukocytosis (30 x 10 9 /L) 

• Monocytes: normal absolute count 

• Leukemic cells have prominent nucleoli, 

absent circumferential shaggy contours 

• BRAF – wild type 

• Absent CD25 / CD123 / Annexin A1 / TRAP 

• No response to Cladribine 

INTRODUCTION 

Demographics 

● Rare, middle-aged to elderly, M>F 


● Splenomegaly, leukocytosis, thrombocytopenia, 

anemia 


Peripheral smear 

● Circulating leukemic cells 


● Cytoplasmic hairy projections noted 

● Nucleus: variable features, condensed chromatin 

with central nuclei or dispersed chromatin with 

irregular nuclear contours 

● Convoluted HCL: Transformation of HCLv to large 

cells with convoluted nuclei 

Bone marrow 

● Aspirable, no dry tap, no fibrosis 

● Marrow infiltration is subtle 

● A distinct predilection for sinusoidal infiltration 

● IHC is needed to assess marrow infiltration 

Spleen 

Red pulp 

● Expanded, diffusely involved 

● Blood lakes 

● Sinusoids are dilated & filled with leukemic cells 

White pulp: Atrophic 

Liver 

● Portal areas & sinusoids infiltrated by leukemic 

cells 

Cytochemistry 

● TRAP is weak to negative 


● Positive: CD72, CD11c, CD103, IgG, FMC7, pan B- 

cell Ag, DBA44, bright monotypic surface IgG 

● Negative: CD25, Annexin A1, TRAP, CD200, CD123 

Characteristic Classic HCL Variant HCL 

Bone marrow 

aspiration 

Difficult (often dry 

tap) 

Lymphocytosis - + 

Monocytopenia + - 

Prominent nucleoli - + 

Cytoplasmic 

projections 

+ + 

CD25 + - 

FMC7, CD20, CD22, 

CD11c 

+ + 

Aspirable 

CD103, CD123 + Variable 

Annexin + - 

BRAF V600E 

mutation 

Response to purine 

analogues 

+ - 

Good 

Table courtesy: Dr Anju Pandey, MBBS, MD 

Poor 

GENETICS 

● No evidence of BRAF V600E mutations 

● Most cases show somatic mutations in IGHV 

(IHGV 4-34) 

● Few cases show p53 mutations 

● DNA copy number alterations: Gain of 

chromosome 5, 7q loss, 17p loss 

● Recurrent MAP2K1 mutations 


● Good 5-year survival 

● Adverse prognostic factors: older age, greater 

severity of anemia, p53 mutation 

● Treatment is splenectomy 

● Cladribine is not effective; however, cladribine 

and rituximab have a long-lasting response 


Chapter 3.6: Lymphoplasmacytic Lymphoma (LPL) 

INTRODUCTION 

● Neoplasm of small B-lymphocytes, plasmacytoid 

lymphocytes and plasma cells 

● MYD88 L265P mutations present 

● IgM paraproteinemia present, but not needed for 

diagnosis of LPL 

● Waldenstrom’s macroglobulinemia (WM) is not 

synonymous with LPL 

Waldenstrom’s Macroglobulinemia (WM) 

● LPL with bone marrow involvement with IgM 

monoclonal gammopathy of any concentration 

● Malignancy of lymphoplasmacytic cells that 

secrete IgM 

● Described in 1948 by Waldenstrom 

● Originate from: Post-germinal center B-cells 

● Have characteristics of IgM bearing memory B- 

cells 

Etiopathogenesis (Figure 1) 

Kshitija Kale 


● Rarely: CNS involvement (“Bing-Neel Syndrome”) 

● Some cases have symptoms related to 

hyperviscosity, such as: 

‣ Epistaxis 

‣ Vascular segmentation and dilatation of 

retinal veins lead to visual disturbances 

‣ Neurologic manifestations: peripheral 

neuropathies, dizziness, headache, transient 

paresis, altered state of consciousness 

● IgM reactivity with MAG (myelin-associated 

glycoprotein) leads to: 

‣ Development of peripheral neuropathies, 

which may precede LPL 

‣ Serum positivity for anti-MAG antibodies 

‣ IgM deposition on skin / GIT causing diarrhea 

‣ IgM binding to clotting factors and fibrin; 

causing coagulopathies 

● In WM, macroglobulin can be pure IgM kind 

cryoglobulins. Thus, the patient’s blood should be 

drawn in a warm syringe and delivered to the lab 

in a warm container. 

Activation of NF-kB 

Figure 1 

● CXCR4 mutations → AKT and ERK1, ERK2 signaling 

→ development of drug resistance 

● Has high BM disease burden, high incidence of 

hyperviscosity 

● ARID1A mutations 

● CD79B mutations 

Demographics 

● Adults, elderly males 


● The disease is mainly localized to bone marrow, 

thus leads to cytopenia related symptoms 

● Weakness and fatigue due to anemia 

● Recurrent infections 

● Rare cases have splenomegaly, hepatomegaly, 

and lymphadenopathy 



● Leucocyte count is lower than that of CLL 

● Circulating lymphoplasmacytoid cells seen +/- 

mast cells 

Bone Marrow 

● Pattern of infiltration: nodular / interstitial +/- 

para-trabecular aggregates 

● Composed of small lymphocytes 

● Admixed with plasma cells + plasmacytoid 

lymphocytes, mast cells, epithelioid macrophages 

with hemosiderin deposits 

Lymph Node 

● Normal architecture is retained 

● Sinuses are dilated and filled with PAS-positive 

material 

● Follicular colonization of monotonous 

proliferation of small lymphocytes, plasma cells, 

plasmacytoid lymphocytes 

● Dutcher bodies (intranuclear pseudo-inclusions), 

mast cells, hemosiderin can be seen 


● May be associated with amyloid, Ig deposition or 

crystal storing histiocytes 


● Most cells express surface immunoglobulins 

● Light chain restricted plasma cells: cytoplasmic Ig 

(IgM > IgG >>> IgA. IgD is never expressed) 

● B-cell : CD5-, CD10-, B cell markers are expressed: 

CD19, CD20, CD22, CD79a 

● Plasma cells: CD138, MUM1, CD19+, CD27+, 

CD81+, CD45+, CD56-, CD117- (In contrast, PCM: 

CD19-, CD27-, CD81-, CD45-, CD56+, CD117+) 

Figure 2; Blue – Lymphocytes, Pink: Plasma cells 

GENETICS 

● IG genes are rearranged (Variable region shows 

somatic hypermutations, biased IGHV gene usage) 

● Majority of cases show MYD88 L265P mutations 

● Some cases show truncating frameshift mutations 

in CXCR4 S338X 

● ARID1A mutations can be seen 

● Less commonly mutations in p53, CD79B, KMT2D 

(MLL2), MYBBP1A 

● Rarely t(9;14) IGH / PAX5 juxtaposition is seen 

● In LPL with predominant marrow involvement can 

show del 6q 

● Trisomy 3, 4, 18 

PROGNOSIS 

● Indolent course 

● Worse prognosis is seen with: 

‣ Advanced patient age 

‣ Cytopenia (especially anemia) 

‣ Poor performance status 

‣ High B 2-microglobulin levels 

‣ Serum paraprotein > 7 g/dl 

‣ More number of transformed cells, 

immunoblasts 

‣ Del 6q 

‣ Absent MYD88 mutations (low response to 

ibrutinib) 

● CXCR4 mutations: more symptomatic disease, 

resistant to ibrutinib 

● Few cases of LPL will progress to DLBCL 

Treatment 

● For severe hyperviscosity symptoms 

(altered consciousness, paresis): 

Plasmapheresis 

● Drugs 

‣ Ibrutinib: BTK inhibitor has a good response, 

the best response is seen in mutated MYD88 

with wild CXCR4 

‣ Rituximab (anti CD20) produces IgM flare; 

hence, prior plasmapheresis is needed 

‣ Rituximab is avoided in high IgM levels 

‣ Alkylating agents: Bendamustine, 

Cyclophosphamide 

‣ Proteasome inhibitors: Bortezomib 

● Newer targets: inhibitors of IRAK1, IRAK4, BCL2 

are being evaluated 


Chapter 3.7: IgM Monoclonal Gammopathy of 

Undetermined Significance (IgM MGUS) 

INTRODUCTION 

● IgM monoclonal gammopathy of undetermined 

significance is a precursor to overt lymphoma or 

primary amyloidosis 

Table 1: Diagnostic criteria for IgM MGUS 

Rama Devi 


● IgM MGUS progress at a rate of 1.5% per year to 

LPL/WM or other B-cell neoplasms 

● Poor prognostic factors are 

‣ Detectable MYD88 L265P mutation 

‣ High levels of serum monoclonal protein 

Serum IGM monoclonal 

protein 

Bone marrow 

lymphoplasmacytic 

infiltration 

Features of 

lymphoproliferative 

disorder 

Chapter 3.8: Heavy Chain Diseases (HCD) 

INTRODUCTION 

Three rare B-cell neoplasms characterized by the 

production of monoclonal immunoglobulin heavy 

chains (Refer to table 1 for the summary) 

● Subtypes: Gamma HCD, Alpha HCD, Mu HCD 

● Immunoglobulins produced include lgG in 

Gamma HCD, lgA in Alpha HCD, and lgM in Mu 

HCD and typically no light chains 

Table 1: Characteristics of Heavy chain diseases 

HCD SITES ASSOCIATED PHENOTYPE 

DISEASES 

ALPHA 

IgA 

GIT, 

Respiratory 

system 

diseases 

Parasitic / bacterial 

intestinal diseases 

Pan B-cell 

Ag+ 

CD138+ 

CD5- 

CD10- 

CD20- 

GAMMA 

IgG 

MU 

IgM 

Bone 

marrow, 

spleen, 

extranodal 

sites 

Bone 

marrow 

Autoimmune 

Diseases 

HSM, 

pulmonary 

infection, 

SLE, systemic 

amyloidosis 

CD19+ 

CD20+ 

CD38+ 

CD138+ 

CD5- 

CD10- 

CD19+ 

CD20+ 

CD38+ 

Kappa 

CD5+ rare 

ALPHA HEAVY CHAIN DISEASE 

● A variant of extranodal marginal zone 

lymphoma of mucosa-associated lymphoid 

tissue (MALT lymphoma) in which defective 

immunoglobulin alpha heavy chains are 

secreted 

Demographics 

● Most common HCD, Mediterranean 

● Young age group, peak second and third decade 

● Low socioeconomic status, including poor 

hygiene, malnutrition, and frequent intestinal 

infections (Campylobacter Jejuni) 


Nupur Sharma 


● Gastrointestinal tract (mainly the small intestine) 

and mesenteric lymph nodes 

● Gastric and colonic mucosa may also be involved 

● Bone marrow and other organs are usually not 

involved 


● Malabsorption, diarrhea, hypocalcemia, 

abdominal pain, wasting, fever, steatorrhea 


Morphology 

● Lamina propria of the bowel is heavily infiltrated 

with plasma cells and admixed small lymphocytes 

● Marginal zone B-cells may be present with the 

formation of lymphoepithelial lesions 

● Lymphoplasmacytic infiltrate separates the 

crypts, and villous atrophy may be present 

● Progression to diffuse large B-cell lymphoma is 

characterized by sheets of large plasmacytoid 

cells and immunoblasts that form solid, 

destructive aggregates with ulceration 


● Plasma cells and marginal zone cells express 

monoclonal cytoplasmic alpha chain without light 

chains 

● Marginal zone: CD20 positive, CD5 and CD10 

negative 

● Plasma cells: CD138 positive, CD20 negative 

GENETICS 

● Clonal rearrangements and somatic hypermutation 

of immunoglobulin genes 

● Deletions in the IGHA gene leads to expression of a 

defective heavy chain protein that cannot bind light 

chain to form a complete immunoglobulin molecule 


● In the early phase, alpha HCD may completely remit 

with antibiotic therapy 

● In patients with more advanced disease, multiagent 

chemotherapy is required 

● Treatment is with anthracycline containing 

regimens 


MU HEAVY CHAIN DISEASE 

INTRODUCTION 

● B-cell neoplasm resembling chronic lymphocytic 

leukemia (CLL), in which a defective mu heavy 

chain lacking a variable region is produced 

● The bone marrow contains an infiltrate of 

characteristic vacuolated plasma cells, admixed 

with small, round lymphocytes 

Demographics 

● Extremely rare 

● Only 30-40 cases reported 

● Elderly, males = females 


● Spleen, liver, bone marrow, and peripheral blood 

● Peripheral lymphadenopathy not seen 


● A slowly progressive disease resembling CLL 

● Differs from CLL in the high frequency of 

hepatosplenomegaly and the absence of 

peripheral lymphadenopathy 

● Immunoelectrophoresis reveals reactivity to antimu 

in polymers of diverse sizes 

● Bence Jones light chains (particularly kappa 

chains) are common (found in the urine in 50% of 

cases) 


Bone Marrow 

● Shows vacuolated plasma cells, which are 

typically admixed with small, round lymphocytes 

like CLL cells 


● Monoclonal cytoplasmic mu heavy chain (with 

or without monotypic light chain), express B-cell 

antigens and are negative for CD5 and CD10 

PROGNOSIS 

● Slowly progressive 

GAMMA HEAVY CHAIN DISEASE 

INTRODUCTION 

● Small B-cell neoplasm with plasmacytic 

differentiation that produces a truncated 

immunoglobulin gamma heavy chain 

Demographics 


● Only 150 cases reported 

● Median patient age of 60 years 

● Female predominance 


● Spleen, liver, bone marrow, and peripheral blood 

● Extranodal sites like Waldeyer’s ring, 

gastrointestinal tract, and others 

● Peripheral lymphadenopathy can be seen 


● Systemic symptoms such as anorexia, weakness, 

fever, weight loss, and recurrent bacterial 

infections 

● Autoimmune manifestations: Rheumatoid 

arthritis, systemic lupus erythematosus, 

autoimmune hemolytic anemia, 

thrombocytopenia, vasculitis, Sjogren syndrome, 

Myasthenia gravis and thyroiditis 

● Has been reported in association with marginalzone 

lymphomas, plasmacytomas, and Hodgkin 

lymphoma 

● Patients generally do not have lytic bone lesions 

or amyloid deposition 

● Diagnosis is made by demonstration of lgG 

without light chains by immunofixation in the 

peripheral blood, the urine, or both 

GENETICS 

● Clonal rearrangements and somatic 

hypermutation of immunoglobulin genes 

● Deletions in the IGHM gene result in the 

expression of a defective heavy chain protein 

that cannot bind light chain to form a complete 

immunoglobulin molecule 


Peripheral Blood 

● May show lymphocytosis with or without 

plasmacytoid lymphocytes, resembling chronic 

lymphocytic leukemia or lymphoplasmacytic 

lymphoma 

Bone Marrow 


● Shows lymphoplasmacytic aggregates or only a 

subtle increase in plasma cells with monotypic 

gamma heavy chains without light chains 

Lymph Node 

● Show a polymorphous proliferation of admixed 

lymphocytes, plasmacytoid lymphocytes, plasma 

cells, immunoblasts, histiocytes, and eosinophils 

(may cause a resemblance to angioimmunoblastic 

T-cell lymphoma or classic Hodgkin lymphoma) 


● Positive: CD79a and cytoplasmic gamma chain 

● Negative: CD5, CD10 

● CD20: lymphocytic component 

● CD138: plasma cell component 

● Kappa and lambda light chains are usually not 

expressed 

GENETICS 

● Clonal rearrangements and somatic 

hypermutation of immunoglobulin genes 

● Deletions in the IGHG gene result in the 

expression of a defective heavy chain protein that 

cannot bind light chain to form a complete 

immunoglobulin molecule 

PROGNOSIS 

● Clinical course is highly variable, ranging from 

indolent to rapidly progressive 


Chapter 3.9 Plasma Cell Neoplasms (PCN) 

INTRODUCTION 

● Neoplasms resulting from an expansion of a 

clone of immunoglobulin secreting, heavy chain 

class-switched, terminally differentiated B-cells 

that secrete M protein 

Subtypes: Refer to table 1 

Non-lgM (plasma cell) 

monoclonal gammopathy of 

undetermined significance 

(precursor lesion) 

Plasma cell myeloma 

Plasmacytoma 

Monoclonal immunoglobulin 

deposition diseases 

Plasma cell neoplasms with 

associated paraneoplastic 

syndrome 

Table 1: Subtypes of PCN 

Clinical variants 

‣ Smoldering plasma 

cell myeloma (SPCM) 

‣ Non-secretory 

myeloma 

‣ Plasma cell leukemia 

‣ Solitary 

plasmacytoma of 

bone 

‣ Extraosseous 

(extramedullary) 

plasmacytoma 

‣ Primary amyloidosis 

‣ Systemic light and 

heavy chain 

deposition diseases 

POEMS syndrome 

TEMPI syndrome 

Reprinted with permission from WHO Classification of tumors, revised 4 th ed, 

Swerdlow SH et al., Plasma cell neoplasms, page 239, 2017 

NON-IgM MONOCLONAL GAMMOPATHY OF 

UNDETERMINED SIGNIFICANCE 

Diagnostic criteria from international myeloma 

working group (IMWG): 

1. Non-lgM MGUS: 

● Serum M protein (non-lgM) concentration

aberrant phenotype (most often either CD19-/ 

CD56+ or CD19-/CD56-) 

GENETICS 

● Translocations involving the IGH locus (14q32) 

● t(11;14)(q13;q32) (IGH/CCND1) 

● t(4;14)(p1 6.3;q32) (IGH/ NSD2, also called 

IGH/MMSET) 

● t(14;16)(q32;q23) 


● The clinical course is stable, with no increase 

in M protein or other evidence of progression 

● Occasionally, there is an evolution to an active 

plasma cell myeloma, solitary plasmacytoma, 

or amyloidosis 

● The risk of progression is about 1% per year 

● Size and type of M protein and serum free light 

chain ratio are significant prognostic indicators 

● Patients with lgG or IgA MGUS with an 

abnormal serum free light chain ratio at 

diagnosis are at higher risk of progression than 

are patients with a normal ratio 

● Individuals with a marked predominance of 

aberrant plasma cells (> 90%) on flow 

cytometry have a significantly higher risk of ● 

progression to myeloma 

● 

PLASMA CELL MYELOMA (PCM) 

● Bone marrow-based, multifocal neoplastic 

proliferation of plasma cells, associated with an 

M protein in serum and/or urine and evidence ● 

of organ damage related to the plasma cell 

neoplasm 

● 

Demographics 

● Older adults 

● 

● Men>Women; Black>Whites 

● 

Etiology 

● Chronic antigenic stimulation from infection or 

other chronic diseases 

● Exposure to specific toxic substances or 

radiation 

● Almost all PCMs arise in patients with a 

precursor MGUS 

Clinical features 

● PCM-related end-organ damage in the form of 

one or more of the following: 

● C: Hypercalcemia; from PCM-induced lytic 

lesions and osteoporosis. 

● R: Renal insufficiency; from tubular damage 

resulting from monoclonal light chain proteinuria 

● A: Anemia; from bone marrow replacement and 

renal damage 

● B: Bone lesions; lytic lesions, bone pain 

● Other clinical and laboratory findings include: 

Infections, bleeding, neurological manifestations, 

pallor, mass disease or organomegaly, 

hyperuricemia, and hypoalbuminemia 

● An M protein is found in the serum or urine in 

majority of cases show lgG; lgA, light chain and 

lgD, lgE, lgM, or biclonality 

Table1: International myeloma working group (IMWG) diagnostic 

criteria for PCM 

Both criteria must be met 

1. Clonal bone marrow plasma cells ≥10% or biopsy proven 

plasmacytoma 

2. Any one or more of the following myeloma defining events: 

● End organ damage attributable to plasma cell proliferative 

disorders 

C: Hypercalcemia; Serum calcium >11mg/dL (2.75mmol/L) OR 

>1mg/dL (0.25mmol/L) higher than the upper limit of normal 

R: Renal insufficiency; Creatinine clearance 2mg/dL (177umol/L) 

A: Anemia, Hb2g/dL below the lower limit of normal 

B: Bone lesions ≥1 osteolytic lesion on skeletal radiography, CT 

or PET/CT 

● Clonal plasma cell proliferation ≥60% 

● Involved: uninvolved serum free light chain (FLC) ratio ≥100 

(involved FLC must be > 100mg/L) 

● >1 focal lesion on MRI (at least 5 mm in size) 


● Few cases are non-secretory 

● The serum M protein is usually > 30 g/L of lgG 

and > 20 g/L of lgA 

● In the majority of patients, there is a 

decrease in polyclonal lg (< 50% of normal) 

Imaging 

● Lytic lesions are common abnormalities on 

skeletal radiography, CT or MRI 

● Others: osteoporosis, pathological fractures, 

and vertebral compression fractures 


● Grossly, the bone defects are filled with soft, 

gelatinous, fish-flesh hemorrhagic tissue 

Bone marrow biopsy 

● Monoclonal plasma cells scattered 

interstitially, in small clusters, in focal 

nodules, or diffuse sheets 

● CD138 staining is useful for quantifying 

plasma cells, and clonality can usually be 

established with staining for lg kappa and 

lambda light chains 

● Aberrant antigens such as CD56 and KIT 

(CD117) may be used to detect populations of 

neoplastic plasma cells 

Bone marrow aspiration (fig 1, 2) 

● The proportion of plasma cells on aspirate 

smears varies from barely increased to >90% 

● Due to the focal distribution of plasma cells in 

some cases, aspirate could be suboptimal 

● Myeloma plasma cells vary from mature to 

immature, plasmablastic, and pleomorphic 

● Variations: 

‣ Mature plasma cells are oval, with a round 

eccentric nucleus, spoke-wheel or clock-face 

chromatin without nucleoli, perinuclear hof 

and abundant basophilic cytoplasm 

‣ Immature forms have more-dispersed 

nuclear chromatin, a higher N:C ratio, and 

(often) prominent nucleoli 

‣ In a few cases, there is plasmablastic 

morphology 

‣ Multinucleated (Fig 2), multilobed, 

pleomorphic plasma cells are prominent in 

some cases 

● Associated morphological findings: 

‣ Mott cells and morula cells: multiple pale 

bluish-white accumulations 

‣ Russell bodies: cherry - red refractive 

round bodies 

‣ Flame cells: glycogen-rich cells 

‣ Pseudo Gaucher cells 

‣ Thesaurocytes 

‣ Crystalline rods 

Figure 1 

Figure 2 


● Rouleaux formation 

● A leukoerythroblastic reaction may be seen 

● Plasma cells, usually in small numbers, are 

found on blood smears 

Kidney 


● Bence Jones protein accumulates as 

aggregates of eosinophilic material in the 

lumina of the renal tubules 

Immunophenotype (Fig 3, 4, 5, 6) 

● Positive: Monotypic cytoplasmic lg (and lack 

surface lg), CD38 and CD138 (Fig 3) 

● CD38 expression signal tends to be dimmer, 

and the CD138 is brighter than in normal 

plasma cells 

● Negative/dim: CD45, CD19, CD27 and CD81 

● Aberrant expression of antigens like CD56, 

CD20, CD28, KIT, CD200, CD52, CD10, and 

occasionally myeloid and monocytic antigens, 

and stem cell-associated antigens 

● May show increased expression of MYC 

● May show increased expression of cyclin D1 

in cases with t(11;14) (IGH/CCND1) and cases 

with hyperdiploidy 

Fig 3: CD138 

Fig 4: Kappa 

GENETICS 

● IG heavy and light chain genes are clonally 

rearranged 

● IGHV gene somatic hypermutation 

● Abnormalities are numerical and structural 

and include trisomies, deletions, and 


● Common translocations involve IgH on 

chromosome 14q32; associated with other 

recurrent translocations 

Fig 5: Lambda 


Table 2: Molecular cytogenetic classification of PCM proposed 

by IMWG 

Genetic category 

Hyper-diploid 

Gains in three or more of the odd-numbered chromosomes 3, 5, 

7, 9, 11, 15, 19, and 21 

Nonhyperdiploid (Translocations of seven oncogenes with IgH 

on 14q32) 

Unclassified (other) 

Cyclin D translocation 

t (11;14): CCND1 

t (6;14): CCND3 

t (12;14): CCND2 

NSD2/MMSET translocation 

t (4;14): NSD2/MMSET 

MAF translocation 

t (14;16): MAF 

t (14;20): MAFB 

t (8;14): MAFA 

Reprinted with permission from WHO Classification of tumors, revised 

4 th ed, Swerdlow SH et al., Plasma cell neoplasms, page 240, 2017 

● IgH translocations and hyper-diploidy appear 

to be an early event in the genesis of PCM 

● Other recurrent genetic changes including 

secondary IGH or IGL translocations; deletion 

and/or mutation of TP53 (17p13); gains of 

chromosome 1q and loss of 1p; mutations of 

genes that result in activation of the NF kappa 

B pathway; mutations of FGFR3 in tumors 

with t(4;14); and inactivation of CDKN2C, RB1, 

FAM46C, and DIS3 

● Other cytogenetic abnormalities include: 

‣ Monosomy or partial deletion of 

chromosome 13 (13q14) 

‣ MYC locus rearrangements: 

‣ Mutually exclusive activating mutations of 

KRAS, NRAS, or BRAF 

‣ Epigenetic changes manifested by DNA 

methylation 

Genetic susceptibility 

Higher risk of PCM in individuals with first degree 

relative with PCM or MGUS 

Table 3: IMWG consensus recommendation on genetic 

testing 

FISH (on cell-sorted samples or cytoplasmic immunoglobulin 

FISH 

Minimal panel: 

t (4;14) 

t (14;16) 

del (17p13) 

More comprehensive panel: 

t (11;14) 

del 13 

ploidy categories 

chromosome 1 abnormalities 

Clinical trials should incorporate gene expression profiling 

Reprinted with permission from WHO Classification of tumors, revised 

4 th ed, Swerdlow SH et al., Plasma cell neoplasms, page 247, 2017 


● PCM is an incurable, progressive disease 

● ISS staging based on serum beta-2 

microglobulin and serum albumin 

● Treatment response measured by MRD 

detection by flow cytometry is a significant 

predictor of both progression-free and overall 

survival, especially following autologous stem 

cell transplantation 

● Factors associated with less favorable 

prognosis: 

‣ Patients aged > 70 years 

‣ Those with significant comorbidities and 

poor performance status 

‣ Reduced polyclonal (uninvolved) serum lg 

‣ Elevated lactate dehydrogenase 

‣ High C-reactive protein 

‣ Elevated serum soluble receptor for IL6 

‣ Increased plasma cell proliferative activity 

‣ A high degree of bone marrow replacement 

and plasmablastic morphology 

PLASMA CELL MYELOMA VARIANTS 

SMOLDERING (ASYMPTOMATIC) PLASMA CELL 

MYELOMA (SPCM) 


IMWG Diagnostic criteria for smoldering PCM: 

Reprinted with permission from WHO Classification of tumors, revised 4 th 

ed, Swerdlow SH et al., Plasma cell neoplasms, page 243, 2017 

Light chain-SPCM 

Both criteria must be met: 

Serum monoclonal protein (IgG or IgA) ≥ 30g/L 

or 

Urinary monoclonal protein ≥ 500mg per 24h 

and/or 

Clonal bone marrow plasma cells 10-60% 

Absence of myeloma-defining events, i.e. (CRAB) and 

amyloidosis 

FEATURE 

M protein concentration 

LC-SPCM 

Urinary LC M protein 

≥0.5g/24 hours 

Percentage of plasma cells in bone 10-60% 

marrow 

End-organ damage attributable to Absent 

the plasma cell disorder 



● Risk factors for progression include 

‣ The presence of both ≥10% bone marrow 

plasma cells and 30 g/L M protein 

‣ Detection of bone lesions by MRI 

‣ A high percentage of bone marrow plasma 

cells with an aberrant immunophenotype 

‣ An abnormal serum free light chain ratio 

‣ A high-risk gene expression profile, a high 

plasma cell proliferation rate, and 

‣ Circulating plasma cells 

● Therapeutic intervention delays progression 

to symptomatic PCM and improves overall 

survival 

● The highest-risk asymptomatic patients are 

defined as those with 

‣ Extreme bone marrow plasmacytosis (>60%), 

‣ An extremely abnormal serum free light chain 

ratio (>100), or 

‣ >1 bone lesion detected by MRI 

● Asymptomatic patients with these 

biomarkers should be considered to have 

active PCM for the purpose of treatment; 

such cases should not be classified as SPCM 

NON-SECRETORY MYELOMA 

● Approximately 1% of PCMs are non-secretory 

● Absence of an M protein by serum and urine 

immunofixation electrophoresis 

● When evaluated by IHC, cytoplasmic M 

protein is present in the neoplastic plasma 

cells in about 85% cases, consistent with 

production but an impaired secretion of lg 

● Minimally secretory or oligo-secretory: 

Elevated serum FLC and/or an abnormal FLC 

ratio 

● Non-producer myeloma: no cytoplasmic lg 

synthesis is detected 

● Genetics: Acquired mutations of the IG light 

chain variable genes and alteration in the 

light chain constant region 

● The clinical features, immunophenotype, 

genetics, and prognosis of non-secretory 

myeloma are similar to those of other PCMs 

● Survival better for patients with a normal 

baseline FLC ratio than those with an 

abnormal ratio 

● D/D: lgD and lgE myelomas, which have low 

serum M protein and may not be routinely 

screened by immunofixation electrophoresis 

PLASMA CELL LEUKEMIA 

● Clonal plasma cells > 20% of total leukocytes 

in the blood or the absolute count >2.0 x 

10 9 /L 

● Bone marrow is extensively and diffusely 

infiltrated 

● Neoplastic plasma cells are frequently found 

in extramedullary sites such as the liver, 

spleen, body cavity effusions, and spinal fluid 

● Can be primary or secondary 

● The median patient age at diagnosis is 

younger than for other myelomas 


● Lymphadenopathy, organomegaly, and renal 

failure are more common, and lytic bone 

lesions and bone pain less common 

● A higher proportion of cases of the light 

chain- only, lgE, and lgD myelomas present 

as PCL compared with lgG or IgA myelomas 

● The immunophenotype of PCL differs from 

other PCMs by its more frequent expression 

of CD20 and less frequent expression of 

CD56 (negative in 80% cases) 

● Higher incidence of high-risk genetic findings 

● Aggressive disease, poor response to therapy, 

and a relatively short survival 

PLASMACYTOMA 

● Solitary plasmacytomas are single localized 

tumors consisting of monoclonal plasma cells 

with no clinical features of plasma cell 

myeloma (PCM) and no physical or 

radiographical evidence of additional plasma 

cell tumors 

● Two types of plasmacytoma: 

‣ Solitary plasmacytoma of bone and 

‣ Extraosseous (extramedullary) 

plasmacytoma 

SOLITARY PLASMACYTOMA OF BONE 

● Solitary plasmacytoma of bone (SPB) is a 

localized tumor consisting of monoclonal 

plasma cells with no clinical features of PCM 

● Radiographical studies, including MRI and CT, 

show no other bone lesions 

● Two distinct types of SPB, with different 

prognoses: 

‣ With no clonal bone marrow plasmacytosis 

except for the solitary lesion and 

‣ With minimal (

one marrow involvement and in 60% of 

those with minimal bone marrow 

involvement(< 10% bone marrow clonal 

plasma cells) 

● Risk factors for progression: 

‣ Older patients 

‣ Patients with an SPB >5 cm 

‣ Persistence of an M-protein for >1 year 

following local radiotherapy 

‣ An abnormal serum free light chain ratio 

‣ Monoclonal urinary free light chains 

‣ Low levels of uninvolved immunoglobulin 

‣ Osteopenia 

EXTRAOSSEOUS PLASMACYTOMA 

INTRODUCTION 

● Extraosseous (extramedullary) 

plasmacytomas are localized plasma cell 

neoplasms that arise in tissues other than 

bone 

Demographics 

● Male>Female, adults 


● Occur most commonly in the mucous 

membranes of the upper air passages 

● Other sites of involvement include the 

gastrointestinal tract, lymph nodes, bladder, 

breasts, thyroid, testes, parotid glands, skin, 

and CNS 

● Plasmacytomas of the upper respiratory tract 

spread to cervical lymph nodes in a few 

cases 

● An indolent variant of lgA-expressing, 

predominantly nodal plasmacytoma has 

been described in younger adults, with 

frequent signs of immune dysfunction 


● Symptoms related to the tumor mass, with 

masses in the upper airway, symptoms may 

include rhinorrhea, epistaxis, and nasal 

obstruction 

● Few patients have a small M protein, most 

commonly lgA 

Microscopy 

● The morphological features are similar to 

those of SPB 


● The immunophenotype appears to be similar 

to that of PCM, with certain differences 

● Extraosseous plasmacytoma usually lacks 

cyclin D1 expression and shows less frequent 

and weaker positivity for CD56 

● Immunophenotype favoring lymphoma over 

plasmacytoma 

‣ Expression of CD20 by lymphocytes within 

the lesion or by the plasmacytoid cells, 

‣ Expression of mu rather than alpha or gamma 

heavy chain, 

‣ On flow: CD19+, CD45+ and CD56- 

Genetic profile 

● Similar to PCM, except for lack of 

t(11;14)(q13;q32) (IGH/CCN01) translocations 

and aberrations of MYC 

Differential diagnosis 

1. Extranodal marginal zone lymphoma (MZL) of 

mucosa-associated lymphoid tissue (MALT 

lymphoma) with plasmacytic differentiation: 

(search for areas with lymphocyte 

proliferation typical of MZL) 

2. Lymphoplasmacytic lymphoma (expression of 

mu rather than alpha or gamma heavy chain) 

3. Plasmablastic lymphoma 

4. Extraosseous infiltrate of plasma cell myeloma 

5. Polytypic reactive plasma cell infiltrates 

(immunohistochemistry or in situ hybridization 

for immunoglobulin light chains) 

PROGNOSIS AND PREDICTIVE FACTORS 

● In most cases, the lesions are eradicated with 

local radiation therapy 

● Regional recurrence develops in few cases, and 

occasionally metastasis to distant extraosseous 

sites 

● Progression to PCM is infrequent 


Clinical features and 

predisposing factors 

Extraosseous infiltrate of 

plasma cell myeloma (PCM) 

Usually in advanced PCM, 

sometimes pure extraosseous 

relapse 

Plasmablastic lymphoma 

HIV infection and 

iatrogenic 

immunosuppression, 

elderly 

immunocompetent 

patients 

Localization Any site Predominantly 

extranodal; oral cavity, 

GI, skin and lymph nodes 

Primary extraosseous 

plasmacytoma 

No known predisposing 

factors, broad patient 

age range, rare cases in 

the post-transplant 

setting 

80% in the head and 

neck region (mostly 

extranodal) 

Osteolytic lesions Common Rare Rare 

M protein Most cases Rare Few cases, low level 

Bone marrow involvement Yes Rare Not seen 

(can manifest 

involvement during 

disease evolution) 

Morphology 


Molecular alteration 

Plasmablastic (PB)/ 

plasma cells (PC) 

PC markers and cytoplasmic 

immunoglobulin (IG) light 

chains positive 

CD56 positive in many cases 

PC leukemia (CD56 -) 

PCM cytogenetic with IG 

translocations (50-70%); 

MYC rearrangement frequent 

with plasmablastic morphology 

Immunoblastic/PB 

Occasionally PC 

PC markers + 

IG light chain + (almost 

half cases) 

B-cell markers negative 

CD56 + in some cases 

PCM type translocation 

absent 

50% MYC rearranged 

Mature PC 

PC markers and 

cytoplasmic IG light 

chain positive 

CD56 -/weak 

Cyclin D1 neg 

t (11;14) and MYC 

rearrangement absent 

EBV infection Absent Majority of patients, Rare 

depending on patient 

background 

Outcome Poor Poor Good, progression to 

PCM in 15% 

Reprinted with permission from WHO Classification of tumors, revised 4 th ed, Swerdlow SH et al., Plasma cell neoplasms, page 254, 2017 

MONOCLONAL IMMUNOGLOBULIN DEPOSITION 

DISEASES 

INTRODUCTION 

● Closely related disorders characterized by 

visceral and soft tissue deposition of aberrant 

lg, resulting in compromised organ function 

● The underlying disorder is usually plasma cell 

neoplasm, or rarely a lymphoplasmacytic 

neoplasm; with Ig deposition preceding the 

development of a large tumor 

● Two major categories of monoclonal lg 

deposition diseases: 

‣ Primary amyloidosis 


‣ Light chain and heavy chain deposition 

diseases 

PRIMARY AMYLOIDOSIS 

INTRODUCTION 

● Caused by a plasma cell or (rarely) a 

lymphoplasmacytic neoplasm in which the 

monoclonal plasma cells secrete intact or 

fragments of abnormal immunoglobulin light 

chains, that deposit in various tissues and 

form a beta-pleated sheet structure (amyloid 

light chain) 

● Most light chain variable (V) region subgroups 

are potentially amyloidogenic, but V lambda 

subgroup VI is always associated with 

amyloidosis 

● In most cases, the diagnostic criteria for 

plasma cell myeloma (PCM) are lacking, but 

there is a moderate increase in monoclonal 

plasma cells in the bone marrow 

Demographics 

● Older adults; Male>female 


● Subcutaneous fat, kidneys, heart, liver, 

gastrointestinal tract, peripheral nerves, and 

bone marrow 

● The diagnostic biopsy site is an abdominal 

subcutaneous fat pad or bone marrow 

● Bone marrow usually shows a monoclonal 

plasma cell proliferation 


● Related to deposition of amyloid in organs; 

including peripheral neuropathy, carpal 

tunnel syndrome, bone pain, congestive heart 

failure, hepatomegaly, macroglossia, purpura, 

malabsorption, proteinuria, nephrotic 

syndrome, and renal failure 

● Hemorrhagic manifestations from factor X 

binding to amyloid, fibrinolysis, and DIC 

● M protein is usually detected (median 

concentration 1.4g/dl) 

● IgG > light chain> IgA> lgM > lgD; the light 

chain is lambda in majority of cases 

● Hypogammaglobulinemia can be seen 

● Hypercalcemia in patients with myeloma 


Macroscopy 

Grossly: Amyloid has a porcelain-like or waxy 

appearance 

Microscopy 

Bone marrow 

● Varies from no pathological findings to a mild 

increase in plasma cells to extensive 

replacement with amyloid, overt PCM, or 

(rarely) LPL 

● Amyloid is present in many tissues and organs 

● On H&E-stained sections, amyloid is a pink, 

amorphous, waxy-looking substance with a 

cracking artifact 

● Found around thickened blood vessel walls, 

on basement membranes, and in the 

interstitial tissues such as fat and bone 

marrow 

● Congo red stains amyloid pink to red by light 

microscopy, and produces apple-green 

birefringence on polarization microscopy 

● Laser microdissection of the amyloid and 

analysis by mass spectrometry is the most 

effective method of characterizing the 

amyloid type 


● Immunohistochemical staining for light chains 

on bone marrow sections usually shows a 

monoclonal plasma cell staining pattern 

● The immunophenotypic features of the 

monotypic plasma cells are similar to those of 

PCM 

GENETICS 

● Similar to those in non-lgM MGUS and PCM, 

except for t(11;14) is more frequently seen as 

compared to non-lgM MGUS or PCM 

● Other frequent chromosomal abnormalities 

include 13q14 deletion and gain of 1q21 



● The primary determinant of outcome is the 

extent of cardiac involvement 

● Other indicators of higher risk are 

‣ Bone marrow monoclonal plasma cells >10% 

‣ High serum free light chain level 

‣ Elevated beta-2 microglobulin 

‣ Multiple organ involvement 

‣ Elevated serum uric acid level 

● The most frequent cause of death is amyloidrelated 

cardiac disease 

LIGHT CHAIN AND HEAVY CHAIN DEPOSITION 

DISEASES 

INTRODUCTION 

● Includes plasma cell or lymphoplasmacytic 

neoplasms that secrete an abnormal light or 

sometimes heavy chain, or both, which 

deposit in tissues, causing organ dysfunction 

● These do not form amyloid beta-pleated 

sheets, bind Congo red stain, or contain an 

amyloid P component 

● They comprise of: 

‣ Light chain deposition disease (LCDD) 

‣ Heavy chain deposition disease (HCDD) 

‣ Light and heavy chain deposition disease 

(LHCDD) 

Demographics 

● Rare, middle-aged, men>women 

● LCDD is the most common, and usually 

occurs in association with PCM; MGUS, and 

rarely with lymphoproliferative disorder 

Sites of involvement 

● Bone marrow shows plasma cell component 

● Deposition of aberrant immunoglobulin (lg) 

may involve many organs, most commonly 

the kidneys, other organs involved are liver, 

heart, lungs, peripheral nerves, blood vessels, 

and joints 

● Prominent deposition of aberrant lg on 

basement membranes, elastic fibers, and 

collagen fibers 


● Organ dysfunction as a result of diffuse, 

systemic lg deposits 

● LCDD is most commonly present with renal 

manifestation. Nephrotic syndrome and renal 

failure are the most common features 

● HCDD of the lgG3 or lgG1 isotype results in 

hypocomplementemia, as they fix 

complement 

● M protein is seen in the majority of cases 

● LCDD: Kappa>lambda 

● HCDD: Gamma> alpha deposition 


Microscopy 

● Bone marrow shows plasma cell proliferative 

disorder, most frequently PCM and rarely 

lymphoproliferative disorder 

● Deposition of the light or heavy chains is most 

commonly observed in renal biopsies 

● The aberrant lg deposits consist of 

amorphous eosinophilic material that is nonamyloid 

and non-fibrillary and does not stain 

with Congo red 

● The deposits consist of refractile eosinophilic 

material in the glomerular and tubular 

basement membranes 

● In LCDD, renal biopsies typically show nodular 

sclerosing glomerulonephritis 

● A hallmark of LCDD is prominent, smooth, 

ribbon-like linear peritubular deposits of 

monotypic lg along the outer edge of the 

tubular basement membrane 

● Immunofluorescence shows mostly kappa 

chains 

● By electron microscopy, these deposits are 

typically non-fibrillary, powdery, and 

electron-dense, with an absence of the betapleated 

sheet structure by X-ray diffraction 


● LCDD has a high prevalence of kappa light 

chains, with an overrepresentation of the V 

kappa IV variable region 


GENETICS 

● The genetic profile of cases associated with 

PCM is similar to that of other PCM 

● In LCDD, defect most commonly involves 

overrepresentation of V kappa IV variable 

region 

● In HCDD, 

‣ Deletion of the CH1 constant domain, leading 

to failure to associate with heavy chain binding 

protein, resulting in premature secretion 

‣ Amino acid substitution in the variable regions, 

causing an increased propensity for tissue 

deposition and binding blood elements 

PROGNOSIS 

● Predictors of higher risk 

‣ Older patient age 

‣ Associated PCM 

‣ Extrarenal light chain deposition 

PLASMA CELL NEOPLASMS WITH ASSOCIATED 

PARANEOPLASTIC SYNDROME 

POEMS SYNDROME 

INTRODUCTION 

● Paraneoplastic syndrome associated with a 

plasma cell neoplasm, usually characterized 

by fibrosis and osteosclerotic changes in bone 

trabeculae, and often with lymph node 

changes resembling the plasma cell variant of 

Castleman disease 

● Comprises: 

‣ Polyneuropathy 

‣ Organomegaly 

‣ Endocrinopathy 

‣ Monoclonal gammopathy 

‣ Skin changes 

● These components are not all required for 

diagnosis 

Epidemiology 

● Rare, seen often in Asia; men>women, 

middle-aged 

Etiology 

● Not well understood 

● Markedly elevated levels of VEGF appear to 

be an important pathogenic event 

● HHV8 infection may play a role 


● M protein: lgG or lgA type, with usually 

lambda light chain restriction 

● For diagnosis: Mandatory criteria + one or 

more major and one or more minor criteria 

(Table 1) 

Table 1: Criteria for the diagnosis of POEMS 

syndrome 

Mandatory criteria 

Polyneuropathy (typically demyelinating) 

Monoclonal plasma cell proliferative disorder 

Major criteria (~ 1 required) 


Osteosclerotic bone lesions 

VEGF elevation 

Minor criteria (~ 1 required) 

Organomegaly (primarily hepatomegaly or 

splenomegaly) 

Endocrinopathy (commonly hypogonadism or 

thyroid abnormality) 

Skin changes (commonly hyperpigmentation and 

hypertrichosis) 

Papilledema 

Thrombocytosis 

Extravascular volume overload 



● Other clinical findings include edema, serous 

cavity effusions, weight loss, fatigue, 

fingernail clubbing, bone pain, and arthralgias 


Microscopy 

● Bone marrow: single or multiple 

osteosclerotic plasmacytoma 

● Composed of focally thickened trabecular 

bone with associated para-trabecular fibrosis 

containing entrapped plasma cells 


● In bone marrow away from the osteosclerotic 

lesion, plasma cells are usually 50% in patients with disseminated 

disease; distributed interstitially or in small or 

large clusters 

● Lymphoid aggregates rimmed by monotypic 

or polytypic plasma cells (in 50% cases) 

● Megakaryocyte hyperplasia in clusters and 

often with atypical morphological features 

● Lymph node biopsies commonly reveal 

plasma cell variant of Castleman disease 


● Bone marrow monoclonal plasma cell 

population in a background of polyclonal 

plasma cells 

● The neoplastic plasma cells are of lgG or lgA 

type and are lambda restricted 

GENETICS: Similar to those in plasma cell myeloma 

PROGNOSIS 

● POEMS syndrome is a chronic and progressive 

disease 

● Patients with localized plasma cell tumors are 

treated with radiation therapy, with an 

improvement of the paraneoplastic 

symptoms 

● Factors associated with shorter survival 

include extravascular fluid overload, 

fingernail clubbing, respiratory symptoms, 

and pulmonary hypertension 

TEMPI SYNDROME 

INTRODUCTION 

● Paraneoplastic syndrome associated with a 

plasma cell neoplasm 

● Stands for Telangiectasias, elevated 

erythropoietin and Erythrocytosis, 

Monoclonal gammopathy, Perinephric fluid 

collection, and Intrapulmonary shunting 

● Included in the WHO as a provisional 

category of PCN 

Demographics: Very rare 

Etiology 

● A suggestion that the monoclonal plasma 

cells and their M protein may play a role in 

the pathophysiology of the disease and its 

paraneoplastic manifestations 


● The clonal plasma cells in the bone marrow 


● Insidious onset with slowly progressive 

symptoms 

● Erythrocytosis with a steadily progressive 

increase in erythropoietin to very high levels 

● Telangiectasia prominent on the face, trunk, 

arms, and hands 

● Intrapulmonary shunting and hypoxia 

● Perinephric fluid collection between the 

kidney and its capsule 

● Spontaneous intracranial hemorrhage and 

venous thrombosis 

● M protein: lgG kappa predominantly 

● Unlike in POEMS syndrome, VEGF levels are 

reportedly normal 


Microscopy 

● Erythrocytosis and a hypercellular marrow 

due to erythroid hyperplasia are recurrent 

findings 

● Most patients have a

Chapter 3.10: Extranodal marginal zone lymphoma of 

mucosa-associated lymphoid tissue 

INTRODUCTION 

● Arise from post germinal center marginal zone B- 

cell 

● Cells include marginal zone centrocyte like cells, 

monocytoid cells, small B lymphocytes, and few 

immunoblasts and centroblasts like cells 

● Neoplastic cells in the marginal zone extend 

interfollicular and follicular areas (follicular 

colonization) 

● Lymphoepithelial lesions are formed in 

epithelial tissues 

Demographics 

● Elderly adults 

● Male =Female, except thyroid and salivary 

gland malt lymphomas, which are more 

common in females 

● Gastric MALT lymphomas: Northeast Italy 

● Infection and autoimmune based associations 

are seen in MALT lymphomas as shown in 

Table 1 

Table 1: Associations with MALT lymphoma sites 

Infection 

Helicobacter pylori Gastric 

Chlamydia Psittaci Ocular adnexal 

Borrelia burgdorferi Cutaneous 

Campylobacter infection Alpha heavy chain disease 

Autoimmune based 

Sjogren syndrome 

Salivary gland 

Hashimoto thyroiditis Thyroid 


● Stomach is the most common site 

● Other: Eyes, ocular adnexa, skin, lungs, salivary 

glands, breast, thyroid 


● Most patients are in Stage I or II disease with few 

showing multiple extranodal involvements 

● Non-gastric MALT lymphomas involve the bone 

marrow and multiple extranodal sites 

● Elevated Serum paraprotein is seen 

● Generalized lymphadenopathy is rare 


Lymph Node 

Nidhi Kataria Rama Devi Akanksha Gupta 

Table 2: Morphologic differentiation at various sites 

Site 

Differentiation 

Salivary gland 

Monocytoid 

Lymph node 

Monocytoid 

Gastric 

Plasmacytic 

Skin 

Plasmacytic 

Thyroid gland 

Plasmacytic (constant 

feature)* 

● Small to medium-sized marginal zone cells with an 

irregular nucleus, dispersed chromatin, 

inconspicuous nucleoli, and pale cytoplasm 

● Neoplastic cells form large confluent areas in the 

marginal zone and can replace germinal centers 

● Mantle zone preserved 

● Can colonize germinal center (differential includes 

follicular lymphoma) 

Epithelial tissues 

● 

Lymphoepithelial lesions are seen (aggregates of 

≥3 neoplastic marginal zone cells with epithelial 

distortion) (Fig 1: conjunctival/ocular MALT 

lymphoma, Fig 2: Lung MALT lymphoma, Fig 3: 

Bone marrow infiltration) 

● Sheets of large transformed cells should be 

diagnosed as DLBCL 

Fig 1: Ocular 


Fig 2: Lung 

Fig 3: BM 

Figure 5 

Immunophenotype (Fig 4,5) 

● Positive for IgM heavy chains, B-cell markers 

(CD20, CD79a) with light chain restriction 

● Negative for CD5, CD10, CD23, BCL6 

● Recent markers: positive for IRTA1, MNDA 

GENETICS (Table 3) 

● Gene mutations and chromosomal numerical 

abnormalities 

● Trisomy of chromosome 3 or 18 

● TNFAIP3 abnormalities on chromosome 6q23 

● MYD88 L265P mutation (rare cases) 


Prognosis 

● MALT Lymphomas are indolent and slow to 

disseminate 

● Sensitive to radiation therapy 

● Prognosis is not worse even when multiple 

extranodal sites and bone marrow is involved 

● Transformation to DLBCL is uncommon 

Treatment 

● Antibiotic therapy for H. pylori leads to remission 

in gastric MALT lymphoma 

● Cases with t(11;18)(q21;q21) are resistant to H. 

pylori eradication therapy 

Figure 4 


Table 3: Genetic alterations in MALT lymphomas 

• IG heavy and light chain gene rearrangements are 

seen with somatic hypermutation of variable regions. 

• Biased usage of certain IGHV genes 

Translocations (related to upregulation of NF kappa B) 

Translocation 

Chimeric 

protein 

Locations 

t(11;18) IAP2/MALT1 Pulmonary and 

gastric tumors 

t(3;14) FOXP1/IGH Thyroid, ocular 

adnexa, orbit, and 

skin 

t(14;18) IGH/MALT1 Ocular adnexa, orbit, 

and salivary gland 

t(1;14) BCL10/IGH Intestine, lung, 

salivary gland 


Chapter 3.11: Nodal Marginal Zone Lymphoma (NMZL) 


INTRODUCTION 

● Marginal zone lymphoma in the lymph node 

that morphologically resembles extranodal or 

splenic type 

● But no organ involvement other than lymph 

node 

● No extranodal or splenic disease 

Demographics 

● Rare, middle-aged to older adults, M=F 

● Can occur in children: labeled as Pediatric Nodal 

Marginal Zone Lymphoma 

Clinical 

● Associated with autoimmune disease, HCV 

infections 

● Asymptomatic lymphadenopathy is seen: 

Localized or generalized, usually in the head 

and neck region. 

● Bone marrow and peripheral blood may be 

involved 

● B symptoms are seen occasionally 

● Marrow infiltration can be seen in one-third of 

the cases 

● Nodal dissemination of extranodal MZL (MALT 

lymphoma) should be ruled out 


Microscopy 

Lymph node (Fig 1, 2) 

● Follicular colonization: neoplastic cells entering 

germinal centers noted in a few cases. It is 

suggested by remnants of follicular dendritic 

cell (FDC) meshwork 

● The neoplastic cell population is composed of: 

‣ Marginal zone B-cells (centrocyte-like, 

monocytoid) 

‣ Plasma cells 

‣ Few transformed B-cells (sometimes more in 

number >20 %) 

‣ Eosinophils may be present 

Figure 2 

● Lymphoid cells may show plasmacytoid 

differentiation 

● Splenic type NMZL type pattern in a few cases 

● Follicular growth pattern: Proliferation of pale 

tumor cells around a reactive germinal center 

and surrounded by an attenuated mantle zone 

Bone marrow 

● Interstitial or nodular involvement 

● Intertrabecular or para-trabecular distribution 

may be seen 


Figure 1 

● Reactive follicles are intact 

● A proliferation of neoplastic cells around the 

follicles and in interfollicular areas 


Pan B markers are expressed 

● CD43 positive 

● BCL2 positive in tumor cells 

● MNDA, IRTA1 positive 

● CD5, CD23, Cyclin D1, germinal center markers 

as CD10, BCL6, HGAL, LMO2 are negative 

GENETICS 

● Clonal rearrangement of IG genes 

● Mutations in IGHV 3 & IGHV 4 genes: IGHV 4-34 

● Mutations in IGHV 1- 69: associated with 

Hepatitis C infection 

● A gain of chromosomes 3 and 18 

● Loss of 6q23-24 

● Increased expression of NF Kappa B related genes 

● MYD88 L265P mutation absent 

PROGNOSIS 

● 5-year survival is good 

● Worse prognosis: advanced age, B symptoms, 

advanced disease stage 

● For prognosis: Follicular Lymphoma 

International Prognostic Index (FLIPI) can be 

applied 


Chapter 3.12: Follicular Lymphoma 


INTRODUCTION 

● Neoplasm of follicle center cells – centrocytes, 

centroblasts/large transformed cells, with at 

least partially follicular pattern 

In situ 

Follicular 

Neoplasia 

Duodenal 

type FL 

Variants of FL 

Testicular FL 

Diffuse 

varaint FL 

Two separate entities 

● Primary follicle center cell lymphoma 

● Pediatric-type FL 

Demographics 

● 50 years, F>M 

● More common in whites 

● Exposure to pesticides, herbicides are a risk 


● Peripheral LN, Spleen, Bone marrow, 

peripheral blood 

● Less commonly Waldeyer’s ring involved 

● Extranodal sites: GIT (mesenteric LN) 

● Also, soft tissues, breast, ocular adnexa 


● Patients present with lymphadenopathy 

● However, B-symptoms are uncommon 


Lymph Node 

● Grossly, enlarged & vague nodules bulge out of 

the cut surface 

Patterns 

Follicular 

component 

Fig 1 

Fig 2: Microscopic patterns of FL in a lymph node 

Follicular 

pattern 

Follicular 

&diffuse 

pattern 

Focally follicular 

/predominantly 

diffuse pattern 

Diffuse 

>75 25-75

Cell size 

Fig 4: Cells encountered in FL 

Centrocytes 

Centroblasts 

Small to mediumsized 

Large ≥3 times of a 

lymphocyte 

Cytoplasm Scant, pale A thin rim of 

cytoplasm 

Nucleus Angulated / 

elongated / twisted / 

Round to oval/ 

irregular/ multilobated 

cleaved 

Nucleoli Inconspicuous 1-3 peripheral 

Ann Arbor staging system 

Figure 7 

Grading 

Fig 5: Grading of FL based on number of Centroblasts 

Number of Centroblasts per HPF 

(40x, 0.159 mm 2 ) 

Grade 1-2 (low grade) 0 – 15 

Grade 1 0 – 5 

Grade 2 6 – 15 

Grade 3 (high grade) >15 

Grade 3A 

Centrocytes present 

Grade 3B 

No centrocytes present 

Staging 

Fig 6: Follicular Lymphoma International Prognostic Index (FLIPI) 

Factors 

Age >60 years 1 

More than four nodal sites affected 1 

LDH elevated 1 

Hemoglobin

‣ CD10 is strong in follicles and weaker in 

interfollicular areas 

‣ BCL6: Downregulated in interfollicular areas 

● Within the follicles: 

‣ CD21, CD23 highlight FDC 

‣ Normal follicular helper T-cells present: CD3, 

CD4, CD57, CD279 (PD1), CXCL13 

● Most cases show germinal center type 

staining; hence IRF4/MUM1 is negative in most 

cases 

● CD10+ cases are IRF4/MUM1 negative 

● Ki67 in grade 1-2 is 20 

% 

Figure 9 

GENETICS 

• Rearrangements of Ig heavy and light chain genes 

• IGHV genes: extensive ongoing somatic 

hypermutations 

• t(14;18) (q32; q31) IGH/BCL2 gene detected by 

FISH 

• Abnormalities in 3q27 and BCL6 rearrangements 

seen in cases of FL and testicular FL 

• Copy number alterations, loss of heterozygosity, 

mutations in the TNFRSF14 gene on chromosome 

1p36 

• A gain of function H3K27 methyltransferase EZH2 

• Driver mutations in CREBBP and KMT2D 

● Activating somatic mutations in RRAGC 

● Inactivation of p53 and CDKN2A and activation 

of MYC seen in transformation to DLBCL 

PROGNOSIS 

● Prognosis of grade 1 to grade 3A is good 

● One-third of cases transform to DLBCL 

● Rare transformation to Hodgkin’s lymphoma 

and histiocytic/dendritic cell sarcoma is noted 

VARIANTS OF FL 

Diffuse FL variant 

● Absent t(14;18) (q32;q21) IGH/BCL2 

● Mainly diffuse involvement with microfollicles 

seen in background, with weak-absent BCL2 

stain 

● Inguinal region LN is involved 

● CD10 , CD23 Positive 

● Del 1p36, containing gene TNFRSF14, is a 

recurrent aberration seen 

Testicular FL 

● Children >>> adults 

● Absent BCL2 translocation 

● Have a higher grade (Grade 3A) 

● Good prognosis 

● Only surgical excision 

● No additional therapy needed 

PRACTICE CAVEATS IN FL 

● FL with an absence of BCL2 are extranodal, 

testicular, higher grades, diffuse variant, 

pediatric FL, primary follicle center lymphoma 

of the skin 

● Diffuse FL with predominant centroblasts 

should be considered as DLBCL 

● FL at extranodal sites are of higher grade and 

do not have BCL2 translocations 

● BM aspirate better be avoided because paratrabecular 

lymphoid aggregates are not 

aspirated well. Hence, in a suspected FL, BM 

trephine biopsy is preferred for assessment 

● Apart from centrocytes and centroblasts, 

rarely, blastoid appearing cells are seen with 


dispersed chromatin. It is equivalent to grade 3 

and has an aggressive clinical course 

● In a few FL, monocytoid B-cells are seen at the 

periphery of neoplastic follicles. They appear 

as a discrete marginal zone. These cells are 

considered as part of a neoplastic clone 

● Plasmacytoid differentiation of neoplastic cells 

can be seen. These cells if in the interfollicular 

distribution, they have BCL2 translocation 

● In intrafollicular plasmacytoid cells, BCL2 

translocation is negative and might constitute 

an unusual variant of MZL with follicular 

colonization 

● Grade 3B-cells usually are CD10 negative, 

BCL2 negative but BCL6 positive 

● CD5 is negative in FL but can be rarely 

expressed in floral growth pattern 

● In some cases, BCL2 mutations eliminate those 

epitopes which are identified by the commonly 

used antibody. Thus, BCL2 can be falsely 

absent. Hence, antibodies against different 

epitopes can be used 

● Although BCL2 overexpression is the hallmark 

of FL, absent BCL2 does not rule out FL 

● In a normal lymph node, BCL2 is also expressed 

in T-cells, primary follicles, and mantle zone 

● Rarely FL can be CD10 negative, IRF4/MUM1 

positive, BCL2 negative, BCL6 positive. Here 

large B-cell lymphoma (having IRF4 

rearrangement and partial follicular pattern) is 

a differential diagnosis 

● A subgroup of morphologically low-grade FL, 

but having a high proliferation index (≥ 30%) 

exists and has an aggressive course. Thus, Ki67 

is a useful adjunct marker 

● FL subsequently develops many subclones; 

hence histological progression and 

transformation are seen over time 

IN-SITU FOLLICULAR NEOPLASIA (ISFN) 

INTRODUCTION 

In – Situ Follicular neoplasia 

Nodal architecture intact 

Follicle size normal 

Involved follicles widely 

scattered 

Mantle cuff intact 

BCL2, CD10 positive 

Composed of centrocytes 

Atypical cells confined to 


● Partial or total colonization of germinal centers 

by clonal B-cells carrying the BCL2 

translocation 

● Can also be seen in reactive follicles in 

lymphoid tissue in other sites, including the 

spleen 

● Important to differentiate from partial 

involvement by follicular lymphoma (FL) 

Demographics 

● Adults >50 years 


Morphology 

● Partial involvement by FL can usually be 

suspected based on H&E stained sections, 

whereas ISFN can only be observed with 

subsequent immunohistochemical stains 


● BCL2: strongly expressed in the follicle, with a 

higher intensity than in adjacent T-cells or 

mantle zone cells 

● BCL2-positive centrocytes also show increased 

expression of CD10 

GENETICS 

● Positive for t(14;18) 

Partial involvement by FL 

Altered architecture on H&E 

Expanded follicles 

Involved follicles grouped 

together 

Mantle cuff attenuated 

BCL2, CD10 variable 

May contain centroblasts as 

well 

May be found outside the 


PROGNOSIS 

● Risk of subsequent FL is extremely low 

● High levels of FL- like B-cells in the peripheral 

blood associated with increased risk of 

subsequent FL 


DUODENAL-TYPE FOLLICULAR LYMPHOMA 

INTRODUCTION 

● Specific variant of FL with distinct features 

● Lesions predominantly found in the second 

portion of the duodenum, presenting as 

multiple small polyps, on endoscopy 

● Most patients have localized disease 

● Survival is excellent even without treatment 

Demographics 

● Middle-aged, M=F 

MICROSCOPY AND PHENOTYPE 

Microscopy 

● Neoplastic follicles are composed almost 

uniformly of centrocytes (with only infrequent 

centroblasts), constituting grade 1- 2 disease in 

the grading system for nodal FL seen in the 

mucosa/submucosa. 


● IHC reveals neoplastic cells also infiltrate the 

lamina propria outside of the follicles 

● Positive for CD20, BCL2, and CD10 

● lgA heavy chain expression seen 

● Variable expression of BCL6 

● Ki67 low 

● Negative for activation-induced cytidine 

deaminase (positive in reactive and neoplastic 

follicles) 

GENETICS 

● Positive for t(14;18) 

● Recurrent deletion of chromosome 1p36 

encompassing TNFRSF14 gene 

● Like MALT lymphomas, there is overexpression 

of CCL20 and MADCAM1 

PROGNOSIS 

● Excellent prognosis 

● May use wait and watch for many patients 


Classical FL with 

intestinal involvement 

Not indolent 

Extensive involvement of 

intestinal wall, into 

muscularis propria 

Variation in cytological 

grade 

Duodenal type FL 

Indolent 

Confined to lamina 

propria 

Uniformly centrocytes, 

grade 1-2 


Chapter 3.13: Pediatric-type Follicular Lymphoma (PTFL) 


INTRODUCTION 

● Lymphoma of young adults and children 

● Most often involves lymph nodes of the head 

and neck, and usually have stage 1 disease 

● Exclude 

‣ Areas of DLBCL or other lymphomas of 

follicle center derivation that occur in the 

children 

‣ Testicular FL 

‣ Large B-cell lymphomas with IRF4 

rearrangement 

Morphology 

Clinical 

features 

IHC 

(required) 

Criteria for diagnosis of PTFL 

● At least partial effacement of nodal 

architecture (required) 

● Pure follicular proliferation (required) * 

● Expansile follicles ** 

● Intermediate-sized so-called blastoid cells 

(not centrocytes) ** 

● Nodal disease (required) 

● Stage 1-2 disease (required) 

● Patient age 30%) 

Genomics ● No BCL2, BCL6, IRF4, or aberrant IG 

(required) rearrangement 

● No BCL2 amplification 

* The presence of any component of diffuse large B-cell 

lymphoma or advanced-stage disease excludes PTFL 

** These are common features of PTFL, but not required for 

diagnosis 

Reprinted with permission from WHO Classification of Tumors, Revised 4th 

Edition, Volume 2, Swerdlow SH et al. Chapter 13, Page 27,, 2017 

Demographics 

● Children, M>F 


● Isolated peripheral lymphadenopathy 

● Enlarged lymph nodes in the head and neck 

region 


● Isolated, asymptomatic LN enlargement 

without abdominal LN involvement 

● No bone marrow involvement 


Microscopy 

● LN architecture totally or sub-totally effaced 

by large expansile follicles, often with a 

serpiginous growth pattern 

● Architectural effacement is a key feature that 

distinguishes PTFL from reactive follicular 

hyperplasia with clonal B-cells 

● Partial involvement can be seen, with a rim of 

normal node at the edge of the biopsy 

● Marginal zone differentiation may be seen 

peripheral to the neoplastic follicles 

● On low-power magnification, the follicles show 

a starry-sky pattern and thin or absent mantle 

zones 

● Monotonous cellular composition: atypical 

cells are intermediate in size, have a blastoid 

appearance, and lack prominent nucleoli 

● Mitotic figures readily apparent 

● Some cases contain more typical centroblasts 

● Areas of DLBCL preclude the diagnosis of PTFL 


● Positive for CD20, CD79a, and PAX5 

● Strong CD10 expression 

● BCL6 is positive 

● Ki67: >30%, loss of polarization of follicles 

● BCL2 negative 

● CD21 and CD23 show intact FDCs 

● Flow cytometry identifies a monotypic 

population of B-cells positive for CD10 and 

negative for CD5 

GENETICS 

● No BCL2, BCL6, KMT2A, CREBBP or IRF4 

mutations 

● Most common genetic aberrations are 

deletion at 1p36 and deletions or mutations 

affecting TNFRSF14 

● MAP2K1 mutation in half of the cases 

PROGNOSIS 

● Excellent 

● Cases with localized disease amenable to 

surgical excision do not require radiation or 

chemotherapy 


Chapter 3.14: Large B-Cell Lymphoma With IRF4 

Rearrangement 


INTRODUCTION 

● Uncommon subtype of LBCL 

● Can be entirely diffuse, follicular and diffuse, 

or entirely follicular 

● Characterized by strong expression of 

IRF4/MUM1, usually with IRF4 rearrangement 

● Occurs primarily in children and young adults, 

with predominantly Waldeyer’s ring or head 

and neck lymph node involvement 

Demographics 

● Rare, children and young adults 


● Lymph nodes of the head and neck region, 

Waldeyer’s ring, gastrointestinal tract 


● Isolated lymph node or tonsillar enlargement 

(stage 1-2) 

GENETICS 

● Cytogenetically cryptic rearrangement of IRF4 

with an IGH locus is detected in most cases 

PROGNOSIS 

● Favorable outcome after treatment 


Microscopy 

● Neoplastic cells are medium-sized to large, 

with more open chromatin than usually seen in 

centrocytes and small basophilic nucleoli 

● Mitotic figures are uncommon, and a starrysky 

pattern is absent 

● When a follicular pattern is present, the 

neoplastic follicles are large, with a back-toback 

growth pattern and absent or attenuated 

mantle zones 

● Many cases have an entirely diffuse growth 

pattern 

● Unlike in pediatric-type follicular lymphoma, 

the follicles do not show a serpiginous 

configuration and starry sky pattern 


● Positive for CD20, CD79a, and PAX5 

● IRF4/MUM1 is typically strongly expressed, 

and BCL6 is positive 

● CD10 and BCL2 expression is observed in many 

cases 

● PRDM1 (also known as BLIMP1) is negative 


Chapter 3.15: Primary Cutaneous Follicle Center Lymphoma 

(PCFCL) 

INTRODUCTION 

● Tumor of neoplastic follicle center cells, including 

centrocytes and variable numbers of centroblasts, 

with a follicular, follicular and diffuse, or diffuse 

growth pattern 

● Generally, presents on the head or trunk 

● Solitary or localized skin lesions on the scalp, 

forehead, or trunk 

Demographics 

● Middle-aged adults, M>F 


● Firm erythematous to violaceous plaques, 

nodules, or tumors of variable size, rarely 

ulceration 

● On the trunk, tumors may be surrounded by 

erythematous papules and slightly infiltrated 

plaques (figurate plaques/ Crosti lymphoma) 

● Skin lesions gradually increase in size over the 

course of several years, but dissemination to 

extracutaneous sites is uncommon 


Microscopy 

Cutaneous follicular 

hyperplasia 

Well defined follicular 

architecture 

Reactive polymorphous 

proliferation 

Tingible body macrophages 

present 

Primary cutaneous FCL 

Poorly defined follicles 

Monotonous proliferation 

Lack of tingible body 

Macrophages 

Mantle zone present Absent mantle zone 

● Perivascular and periadnexal to diffuse infiltrates, 

with sparing of the epidermis 

● Growth patterns show a spectrum, with a 

morphological continuum from follicular to 

follicular and diffuse to diffuse 

● Cases with a diffuse growth pattern usually show 

a monotonous population of large centrocytes, 

some of which may have a multilobated 

appearance and variable numbers of admixed 

centroblasts 


● Positive: CD20 and CD79a, BCL6 


● CD10 positive in cases with a follicular growth 

pattern, negative in cases with a diffuse growth 

pattern 

● Flow cytometric studies show restricted light 

chain expression in 3/4 of cases in cases 

immunoglobulin negative by IHC 

● Negative: BCL2, IRF4/MUM1, FOXP1, CD5, and 

CD43 

GENETICS 

● BCL2 rearrangements in about 10- 40% of PCFCL 

with a follicular growth pattern, as well as in some 

diffuse cases 

● Inactivation of CDKN2A and CDKN2B gene loci on 

chromosome 9p21.3 by deletion or promoter 

hypermethylation is only rarely found (useful to 

distinguish from primary cutaneous diffuse large 

B-cell lymphoma, leg type) 

PROGNOSIS 

● Excellent 

● PCFCL presenting on the leg reported having a 

less favorable prognosis 


Chapter 3.16: Mantle Cell Lymphoma (MCL) 

INTRODUCTION 

● Mature B-cell lymphoma of small and mediumsized 

monomorphic cells with CCND1 

translocation in most cases 

● Characterized by a lack of large/ transformed cells 

and proliferation centers, and aggressive clinical 

course 

Cell of origin 

● Naïve B-cell of the inner mantle zone, however, 

some are of post-germinal center origin with 

clonal rearrangements of Ig genes 

● IGV genes are unmutated, a subset showing 

somatic hypermutations demonstrates a biased 

use of IGHV genes 

Demographics 

● Middle to older age group, male preponderance 


● Lymph nodes (most common), spleen and BM, 

with or without PB involvement, extranodal sites 

(Waldeyer’s ring, lungs, GIT [multiple 

lymphomatous polyposis]) 

● CNS involvement (at relapse) 


● Advanced stage disease with lymphadenopathy, 

organomegaly, marrow and peripheral blood 

involvement at presentation is common 


Lymph Node (Table 1) 

Table 1: Variants of Mantle cell Lymphoma 

Nidhi Kataria 


● Small to medium lymphoid cells with irregular 

nuclear contours and dispersed chromatin (Fig 2) 

● Allied features: hyalinized small vessels (Fig 1), 

singly scattered epithelioid histiocytes (with 

blastoid or pleomorphic background mimics 

starry-sky appearance); non-neoplastic plasma 

cells present 

● Proliferative fraction (mitotic count/ Ki67 index) 

is extremely important prognostically 

● Histological transformation to diffuse large B-cell 

lymphoma does not occur 

Peripheral Smear/Bone Marrow 

● Cells may show prominent nucleoli, resembling 

PLL, acute leukemia or CLL 

Figure 1 

Aggressive 

Blastoid 

(Fig 3) 

Pleomorphic 

Lymphoblast-like cells showing 

open chromatin and brisk mitoses 

Mixture of large and pleomorphic 

cells showing nuclear irregularity 

and conspicuous nucleoli 

Indolent Small cell Cells resembling SLL-cells, usually 

found in leukemic non-nodal 

mantle cell lymphoma 

Marginal zonelike 

Clusters of monocytoid B-cells, 

resembling either a marginal zone 

lymphoma or proliferation center 

of CLL/SLL 

● Classical: Monomorphic cells arranged in 

nodular/diffuse/mantle zone/follicular pattern 

(rare) 

Figure 2 


Fig 3: Blastoid variant 

Spleen 

White pulp 

● Central zone of small tumor cells surrounded by 

larger paler cells at periphery merging into red 

pulp (D/D SMZL) 

Red pulp 

● Shows infiltration 


● Positive: surface lgM/lgD (bright), lambda > 

kappa, cyclin D1 (BCL1), SOX11, CD5, FMC7, CD43, 

BCL2 

● Negative: CD10, BCL6, CD23 

● Aberrant phenotypes 

‣ CD5- and CD10+, BCL6+ 

‣ Expression of CLL associated antigens, such 

as LEF1 (in blastoid/pleomorphic variant) 

or CD200 (in leukemic non-nodal variant) 

GENETICS 

● t(11;14) (q13;q32); (IGH; CCND1) (encoding cyclin 

D1) and truncated transcripts result in high levels 

of cyclin D1 expression 

● High genomic instability due to aberrations in 

MYC, ATM, TP53, trisomy 12, BCL6, tetraploidy 

(seen in the majority of pleomorphic variant), 

NOTCH1/2, CDKN2A and CDKN2C, RB1, CDK4 

genes 

● Genetic susceptibility is seen 

PROGNOSIS 

● Incurable, short median survival 

Figure 4 

Figure 5 

● MCL International Prognostic Index (MIPI) score 

‣ Ki67 

‣ Age 

‣ ECOG performance score 


‣ Lactate dehydrogenase level 

‣ WBC count 

● Adverse prognosis factors 

‣ Brisk mitoses, Ki- 67 (> 30%) 

‣ Blastoid/pleomorphic morphology 

‣ Leukemia with adenopathy 

‣ Complex karyotype 

‣ TP53 alteration, CDKN2A deletion 

● An indolent course is seen in small cell variant 

and nodular pattern 

LEUKEMIC NON-NODAL MANTLE CELL LYMPHOMA 

(LNN-MCL) 

INTRODUCTION 

● Small cells resembling CLL cells, involving blood 

+ bone marrow ± spleen, without significant 

adenopathy (Table 2) 

GENETICS 

● CCND1 translocation 

PROGNOSIS 

● Better prognosis than those with classic mantle 

cell lymphoma 

● Usually indolent course, often not requiring 

therapy for long periods 

● TP53 mutations may be associated with 

aggressive evolution 

of classical MCL with a mantle zone growth 

pattern 

● Peripheral blood or extranodal sites may also be 

involved 

PHENOTYPE 

● CD5 may be negative, SOX 11 +/- 

PROGNOSIS 

● Found incidentally, indolent course, progression is 

rare 

Table 2: Differentiation between classic MCL, LNN-MCL and CLL 

Classic MCL LNN-MCL CLL 

Cells Small – Small Small 

medium 

HSM - + +/- 

SOX11 + - - 

CD5 + +/- + 

CD200 - +/- + 

Course Aggressive Indolent, 

rarely 

progress 

Indolent, may 

progress 

IN-SITU MANTLE CELL NEOPLASIA 

INTRODUCTION 

● Characterized by atypical lymphoid cells 

occupying only the inner mantle zone of a 

reactive follicle, and showing positivity for cyclin 

D1 with CCND1 rearrangements 


● Scattered cyclin D1-positive cells rarely may 

involve the outer mantle zone 

● Complete replacement of mantle zone by cyclin 

D1- positive lymphoid cells warrants a diagnosis 


Chapter 3.17: Diffuse Large B-cell Lymphoma, Not 

Otherwise Specified (DLBCL, NOS) 


INTRODUCTION 

● Neoplasm of medium or large B lymphoid cells 

with nuclei that are the same size as, or larger 

than, those of normal macrophages, or more 

than twice the size of those of normal 

lymphocytes, with a diffuse growth pattern 

Germinal center B-cell 

Type (GCB) 

Subtypes 

Figure 1 

Activated B-cell type (ABC) 

Demographics 

● Most common adult Non-Hodgkin lymphomas 

in developed countries 

● Higher percentage in developing countries 

● Median age: seventh decade 

● More common in males 

Etiology 

● De Novo 

● Secondary: Transformation from less aggressive 

lymphoma, i.e., chronic lymphocytic 

leukemia/small lymphocytic lymphoma, 

follicular lymphoma, marginal zone lymphoma, 

or nodular lymphocyte predominant Hodgkin 

lymphoma 

● DLBCL, NOS, occurring in the setting of 

immunodeficiency are more often EBV-positive 

than sporadic cases 

● EBV positivity in most tumor cells should lead 

to a diagnosis of either EBV positive DLBCL, 

NOS, or another specific type of EBV-positive 

lymphoma 


● Nodal 

● Extranodal sites: Gastrointestinal (stomach and 

ileocaecal region), bone, testes, spleen, 

Waldeyer’s ring, salivary glands, thyroid, liver, 

kidneys, and adrenal glands 

● Primary CNS lymphoma and primary testicular 

lymphoma (immune-privileged sites) 

● Bone marrow: Concordant or discordant 

involvement 

● FDG-PET is a sensitive technique for detecting 

concordant bone marrow involvement 

● Consensus criteria for lymphoma staging indicate 

that a routine staging bone marrow biopsy is no 

longer required if FDG-PET is negative 


● Rapidly enlarging tumor mass at single or multiple 

nodal or extranodal sites 

● Nearly 50% of patients have stage I or II disease 

● Some patients are asymptomatic, but B symptoms 

may be present 


Lymph Node (Fig 2) 

● Architectural effacement by diffuse proliferation 

of medium or large lymphoid cells 

● Partial nodal involvement may be interfollicular 

and/or less commonly sinusoidal 

● Perinodal tissue is often infiltrated 

● Broad or fine bands of sclerosis may be present 

● Special studies are required to exclude 

extramedullary leukemias, Burkitt lymphoma, 

high-grade B-cell lymphoma with MYC and BCL2 

and/or BCL6 rearrangements, and blastoid mantle 

cell lymphoma due to all having medium-sized 

cells 

Variants 

Morphological 

variants 

Figure 3 

Centroblastic Immunoblastic Anaplastic Others 

Figure 2 


Chapter 3.17: Diffuse Large B-cell Lymphoma, Not 

Otherwise Specified (DLBCL, NOS) 


Centroblastic variant 

● Most common variant 

● Usually GCB type 

● Centroblasts are medium-sized to large lymphoid 

cells with oval to round, vesicular nuclei 

containing fine chromatin 

● 2- 4 nuclear membrane-bound nucleoli 

● Scant amphophilic or basophilic cytoplasm 

● Cells may have multilobated nuclei, in tumors 

localized to the bone and other extranodal sites 

Immunoblastic variant 

● >90% of the cells are immunoblasts, with a single 

centrally located nucleolus and abundant 

basophilic cytoplasm 

● Clinical and/or immunophenotypic findings may 

be essential in differentiating this variant from 

extramedullary involvement by a plasmablastic 

lymphoma or an immature plasma cell myeloma 

due to occasional plasmacytoid appearance of 

cells 

Anaplastic variant 

● Characterized by large cells with bizarre 

pleomorphic nuclei that may resemble Hodgkin 

Reed Sternberg cells and the neoplastic cells of 

anaplastic large cell lymphoma 

● Cells may show a sinusoidal and/or a cohesive 

growth pattern and may mimic undifferentiated 

carcinoma 

● The anaplastic variant is biologically and clinically 

unrelated to anaplastic large cell lymphoma, 

which is of cytotoxic T-cell derivation 

● Anaplastic variant is unrelated to ALK-positive 

large B-cell lymphoma, which lacks expression of 

CD20 and CD30 

Special subtypes 

Primary Breast DLBCL 

Most cases are of the ABC subtype and show 

recurrent MYD88 L265P and CD79B mutations, 

like nodal ABC DLBCL, NOS 

● Rearrangements of either BCL2 or BCL6 are rare 

Primary Gastric DLBCL 

● Primary gastric DLBCL are mostly of the ABC 

subtype 

● Recurrent mutations of MYD88 and CD79B are 

uncommon 

● Translocations involving BCL6 and MYC 

rearrangements can be seen, but BCL2 

translocations are uncommon 

Primary testicular DLBCL 

● Most cases are of the ABC subtype 

● High frequency of MYD88 mutations, 

accompanied in a subset of cases by CD79b 

mutations 

● Testicular DLBCL, NOS, can spread to the CNS 

and the contralateral testis 

Immunophenotyping (Fig 4) 

● Positive: Pan-B-cell markers such as CD19, CD20, 

CD22, CD79a, PAX5 and surface and cytoplasmic 

immunoglobulin (most commonly lgM, followed 

by lgG and lgA), BCL2, MYC 

● Increased forward scatter 

Figure 4 

● CD30 may be expressed in 10-20% of cases, 

especially in the anaplastic variant 


● CD5+ DLBCL can be distinguished from the 

blastoid or pleomorphic variant of mantle cell 

lymphoma by the absence of cyclin D1 and/or 

SOX11 expression 

● BCL2 is considered positive if ≥50% of the tumor 

cells are positive, and MYC is considered positive 

if ≥40% of the tumor cell nuclei are positive. Coexpression 

is seen in ABC subtype 

● Hans algorithm: Refer to Figure 5 

● CD10, BCL6, and IRF4/MUM1 are each considered 

positive if ≥30% of the tumor cell stain positively 

● FOXP1 expression seen in few DLBCL cases that 

lack the germinal center phenotype and express 

IRF4/MUM1 and BCL2 in the absence of t(14;18) 

● GCET1, a germinal center marker, is expressed in 

some cases and is correlated with the GCB type 

● LM02 expression is highly correlated with the 

germinal center markers CD10, BCL6, and HGAL 

● Ki67 proliferation index is high 

● Cell of origin subtyping is necessary because 

studies suggest that the benefit from the addition 

of bortezomib, lenalidomide, and ibrutinib to R- 

CHOP is preferentially seen in the ABC subtype 

Figure 5 

Han’s algorithm for categorizing into GCB and ABC subtypes. 

GENETICS 

GCB subtype 

● EZH2 and GNA13 mutations 

● Gains or amplification of 2p16 and 8q24 and 

deletions of 1p36 

● Translocation of the BCL2 gene, i.e., t(14;18) 

more common 

ABC subtype 

● Prior somatic mutation 

● CARD11, MYD88, and CD79B mutations 

● Gains of 3q27, 11q23-4, and 18q21 and 

deletions of 6q21 and 9p21 

● Higher frequency of BCL6 rearrangement 

Double Hit Lymphoma 

● Half of the DLBCL cases that harbor a MYC 

translocation also show a BCL2 and/or BCL6 

translocation, and belong in the newly created 

category of high-grade B-cell lymphoma with 

MYC and BCL2 and/or BCL6 rearrangements 

(previously so-called double-hit lymphoma) 

Double Expressors: 

● Positive for both MYC and BCL2 protein on IHC, 

no rearrangements 


Poor prognostic factors: 

● Masses >10 cm, male sex, vitamin D deficiency, 

low body mass index, elevated serum free light 

chains, monoclonal serum lgM proteins, low 

absolute lymphocyte/monocyte count, and 

concordant bone marrow involvement 

● Concordant bone marrow involvement and 

double expressors have an increased risk of CNS 

relapse 

● CD5+ DLBCL associated with high-risk clinical 

features, especially in Asian countries, and is 

usually of ABC subtype 

● Double-expression status of MYC and BCL2 

proteins 

● Presence of a BCL2 translocation in GCB subtype 

● MYC translocations (occur in few DLBCL cases) 

● MYC and BCL2 double-hit lymphomas 

● TP53 loss and/ or mutations 

● Deletions of the CDKN2A locus on chromosome 

9p21 and trisomy 3 (ABC subtype) 

● Loss of MHC class II (associated with decreased 

tumor infiltrating CD8+ T-cells) 

● Overexpression of PDL1 

Good prognostic factors: 

● Translocation of BCL6 (mostly in ABC DLBCL) 

● SNPs involving loci at 5q23.2 and 6q21 have been 

associated with event free survival in patients 

with DLBCL treated with R-CHOP 


Chapter 3.18: T-cell Histiocyte Rich Large B-cell Lymphoma 

(THRLBCL) 

INTRODUCTION 

● Scattered, large B-cells embedded in the 

background of abundant T-cells and histiocytes 

● Origin: de novo or progression from nodular 

lymphocyte predominant Hodgkin lymphoma 

(NLPHL) 

Demographics 

● Rare, middle-aged, Male > Female 


● Most common: lymph nodes 

● Other sites: bone marrow, liver, and spleen 


● Fever, malaise, HSM 

● Advanced Ann Arbor stage 

Radiology 

● NLPHL usually affects one or two regions, while 

THRLBCL manifests as a systemic disease 

● THRLBCL is more PET-avid than NLPHL, staging 

procedures such as FDG-PET and CT may aid in 

the differential diagnosis 


Lymph Node 

● Pattern: diffuse or vaguely nodular replacing 

most of the normal lymph node parenchyma 

● Consist of dispersed, single large B-cells in the 

background of small T-cells and variable numbers 

of bland-looking non-epithelioid histiocytes 

● large B cells may mimic lymphocyte predominant 

(LP) cells of NLPHL, centroblasts or maybe more 

pleomorphic 

● Absent follicular dendritic cells meshwork 

● On recurrence: the number of atypical cells may 

increase, resembling DLBCL and rendering an 

inferior outcome 

● Cases lacking histiocytes are currently included in 

the THRLBCL category with the note about the 

paucity or absence of histiocytes 

● Cases with sheets of neoplastic B-cells should not 

be included within this category and may be 

considered a subtype of DLBCL, NOS 

Spleen: Multifocal / micronodular involvement of white 

pulp 

Nidhi Kataria 


Liver: Lymphomatous foci in the portal tracts 


● Neoplastic cells express pan-B markers and BCL6 

● Variable expression of BCL2 and EMA 

● Negative for CD15, CD30, or CD138 

● The background consists of CD68+ and CD163+ 

histiocytes and CD3+ and CD5+ T-cells 

GENETICS 

● Clonally rearranged IG genes 

● Gains of 2p16.1 and losses of 2p11.2 and 9p11.2 

● Histiocytes from NLPHL and THRLBCL showed 

similar gene expression profiles, except those 

from THRLBCL express metal-binding proteins 

● Expression profiling and genetic studies suggest 

that NLPHL and THRLBCL constitute a pathological 

continuum 

● More genetic aberrations in NLPHL than in de 

novo THRLBCL 


● IPI score is of prognostic significance 

● Aggressive lymphoma 

● Refractory to chemotherapy currently in use 

Table 1: THRLBCL vs NLPHL vs LRCHL 

THRLBCL NLPHL LRCHL 

Architecture Diffuse Nodular Nodular/Diffuse 

Classic RS cells -/+ -/+ + 

CD45 + + _ 

CD30 _ _ + 

CD15 _ _ +/- 

CD20 + + -/+ 

CD79a + +/- _ 

EBV _ _ +/- 

Background T>>>B B>>>T B>T 

lymphocytes 

CD21 FDC _ + _ 

BM inv +/- -/+ -/+ 


Chapter 3.19: Primary CNS DLBCL 

Vanya Jaitly 


INTRODUCTION 

● DLBCL arising within the brain, spinal cord, 

leptomeninges or eye 

● Exclude: 

‣ Lymphomas of the dura 

‣ Intravascular large B-cell lymphomas 

‣ Secondary lymphomas 

‣ Immunodeficiency related lymphomas 

Demographics 

● Rare, adults, M > F 

Etiopathogenesis and sites of Involvement 

● Etiology: unknown 

● No association with viruses including EBV, HHV6, 

HHV8, polyomaviruses SV40 and BK virus 

● Chemokines, chemokine receptors or 

cytokines may play a role in the localization 

● Most common site: supratentorial space 

● Other sites: basal ganglia and periventricular 

brain parenchyma, corpus callosum, posterior 

fossa and spinal cord 

● Single tumor (most cases), while multifocal 

disease in the remaining cases 

● Exclusive leptomeningeal involvement is unusual 

● Intraocular lesions mostly develop contralateral 

tumors and parenchymal CNS lesions 

● Preferential spread to the testis has been noted 

● On relapse, restriction to immune-privileged sites 

(i.e., the brain, eyes, and testes) 


● Cognitive dysfunction, psychomotor slowing, and 

focal neurological symptoms 

● Ocular involvement: blurred vision and eye 

floaters 

● MRI most sensitive technique for detection 

● Important to withhold corticosteroids before the 

biopsy, as they lead to rapid tumor shrinkage 


Gross 

● Single or multiple masses in the brain 

parenchyma 

● Firm, friable, granular, hemorrhagic, greyish-tan 

or yellow, with central necrosis 

● May appear well defined, like metastases or may 

resemble gliomas 

● Meningeal involvement grossly inconspicuous 

Microscopy 

● Stereotactic biopsy is the gold standard for 

diagnosis 

● Highly cellular, diffusely growing tumors 

● Central large areas of geographical necrosis with 

perivascular lymphoma islands, usually at the 

periphery 

● Invasion of the neural parenchyma, either as 

small clusters or as single tumor cells, 

accompanied by reactive gliosis and inflammation 

● Atypical cells have centroblasts or immunoblasts 

like morphology 

● In cases with scattered tumor cells, IHC with B-cell 

markers like CD20 can aid in diagnosis 


● Positive for 

‣ Mature B-cells markers 

‣ Surface lgM and lgD with light chain restriction 

‣ IRF4/MUM1 most cases, BCL6 (>half cases) 

● BCL2-strong, MYC-strong: most cases 

● BCL2 expression unrelated to t(14;18) 

● Brisk mitotic activity and high Ki67 > 70% 

● Negative for plasma cell markers 

● CD10 expression should prompt search for 

systemic DLBCL 

● Loss of major histocompatibility complex (MHC) 

class I and/or II expression (50% cases) 

● No evidence of EBV infection (think about 

immunodeficiency associated CNS lymphomas) 

GENETICS 

● Cell of origin is late germinal center B-cell with 

arrested terminal B-cell differentiation, so will 

show features of both germinal center and 

activated B-cell 


● Rearranged and somatically mutated IG genes 

with ongoing somatic hypermutation 

● Persistent BCL6 activity 

● lgM/lgD phenotype due to miscarried IG classswitch 

rearrangements with deletion of 

S-mu region and PRDM1 mutations 

● Translocations involving IG genes and BCL6 

● A gain of genetic material involving 18q21.33-23 

including the BCL2 and MALT1 genes, 

chromosome 12 and10q23.21 

● Loss of genetic material including 6q21, 6p21 

(harboring MHC class II gene), 8q12.1-12.2, and 

10q23.21 

● MYD88 L265P mutation 

● Activation of pathways including toll-like receptor, 

and the NF-kappa B pathway 

● Epigenetic changes including gene silencing by 

DNA methylation carry therapeutic relevance 


Prognosis 

Prognosis 

Good 

Bad 

Reactive 

perivascular 

CD3+ T-cells 

LMO2 

expression 

Age > 65 

years 

del 6q22 

Treatment 

● Worse outcome 

● Treated with high-dose methotrexate based 

polychemotherapy 

● Irradiation may improve outcome, 

but carries the risk of neurotoxicity 

● In a study of elderly with methylated MGMT, 

temozolomide appeared to be effective 


Chapter 3.20: Primary cutaneous DLBCL, leg type 

INTRODUCTION 

● Diffuse large B-cell lymphoma (DLBCL) arising in 

cutaneous locations, most often in the lower legs 

● Differential includes primary cutaneous follicle 

center lymphoma, monomorphic post-transplant 

lymphoproliferative disorders (PTLDs), 

plasmablastic lymphomas and systemic DLBCLs 

involving the skin 

Demographics 

● Elderly 

● Female preponderance 


● Cutaneous most commonly leg but other sites 

may be involved 


● Single or multiple tumors 


Skin 

● Diffuse sheets of large monomorphic cells in the 

dermis causing architectural effacement with 

epidermal sparing 

● Cells can be Immunoblastic or Centroblastic 

● Absence of background small B-cells or reactive T- 

cells 

● Absence of follicular dendritic cell meshwork 


● Pan B-cell markers are positive 

● BCL2, IRF4/MUM1, FOXP1, MYC, BCL6 positive 

● Cytoplasmic IgM positive 

● High ki67 

Cell of origin 

● Post germinal center B-cell 

GENETICS 

● Monoclinal IgH gene rearrangement 

● IGH translocation with MYC or BCL6 

● BCL2, MALT1 genes are frequently amplified 

● CDKN2A, CDKN2B loss 

● MYD88 L265P activating mutations 

● Mutations in CARD11, CD79B, and TNFAIP3 

● Activation of NF-kappa B pathway on gene 

expression profiling 

Vanya Jaitly 



Prognosis 

● MYD88 L265P mutations, CDKN2A loss, and 

multiple skin tumors are poor prognostic factors 

Treatment 

● RCHOP (rituximab, cyclophosphamide, 

doxorubicin, oncovin, prednisone) 


Chapter 3.21: EBV-positive DLBCL, NOS 

INTRODUCTION 

● Includes diffuse large B-cell lymphomas which are 

EBV+, but do not fit into other well defined EBV+ 

entities 

● Differential includes other EBV positive disorders 

like lymphomatoid granulomatosis, classic 

Hodgkin lymphoma, plasmablastic lymphoma, 

DLBCL associated with chronic inflammation and 

EBV positive mucocutaneous ulcer 

● Aging associated immune dysregulation plays a 

role in the development 

● A small number of EBV positive cells can be seen 

in many lymphomas and should not be 

categorized as EBV positive DLBCL, NOS 

Demographics 

● Elderly (8 th decade), second peak- 3 rd decade 

● Asians, Latin Americans > Westerners 


Pathogenesis 

● EBV is a gamma herpesvirus which can infect 

lymphocytes, NK cells, and epithelial cells 

● B lymphocytes are infected via the CD21 receptor 

● The virus remains latent, but certain viral genes 

are transcribed upregulating proliferation and 

transformation of the infected cell 

● EBV type II or III latency pattern is seen in EBV 

positive DLBCL, NOS 

Table 1: EBV Latency patterns 

Vanya Jaitly 


● Presence of B symptoms, high international 

prognostic score at presentation 

Lab tests 

● High LDH 

● EBV positive on serologic testing 


Lymph node and extranodal sites 

● Spectrum of morphology varies from polymorphic 

to monomorphic 

● Polymorphic: immunoblasts and RS-like cells 

in a polymorphic background (THRLBCL like) of 

plasma cells, histiocytes, and small lymphocytes 

● Monomorphic: large cells resembling DLBCL 

in sheets 


● B-cell markers positive 

● IRF4/MUM1 positive 

● CD10, BCL6 negative 

● CD30, CD15 often positive 

● EBER positive in the majority (>80%) of tumor 

cells 

● EBV type III or II latency pattern 

GENETICS 

● Monoclonal IGH gene rearrangement 

● Gains of 9p24.1 

● Activation of JAK/STAT and NF-kappa B 

pathways on gene expression profiling 

Latency 

Genes expressed 

0 EBER 1, EBER 2, BART miRNA 

I EBER 1, EBER 2, BART miRNA + EBNA 1 

II EBER 1, EBER 2, BART miRNA + EBNA 1 + 

LMP1, LMP 2A 

III All genes are expressed, including EBNA 

3A, 3B, 3C 


● Younger patients have excellent prognosis 

● Patients with polymorphic pattern have better 

prognosis 

● CD30 positivity, EBNA2 positivity, old age and 

presence of B symptoms are poor prognostic 

factors 


● Lymph nodes 

● Extranodal sites: lungs, stomach, skin 



Chapter 3.22: EBV positive mucocutaneous ulcer 

INTRODUCTION 

● Newly recognized 

● Immunosuppression-related 

● Defective surveillance for EBV 

● Typically, indolent course and spontaneous 

regression 

Demographics 

● Above 70 years, males 

Pathogenesis 

● In the elderly age group, the T-cell responses 

to EBV infection are altered 

● Accumulation of clonally restricted CD8 + T- 

cells which have diminished functionality 

● Hence these lesions are at the sites prone to a 

local trauma 

Kshitija Kale 



● Ulcerated lesions in oral cavities, GIT 

(esophagus, rectum, perianal region) 

● Occasionally regional LN are enlarged, but 

exhibit reactive hyperplasia only 

● Systemic LN not involved 


Lesions 

● Well circumscribed, indurated ulcers 

Microscopy (Fig 1-3) 

● Mucosa: ulcerated and adjacent 

pseudoepitheliomatous hyperplasia noted 

● Submucosa: well-circumscribed lesion 

Figure 1 

Figure 2 Figure 3 


Immunophenotyping (Fig 4,5) 

● B-cell markers: CD20 +/-, PAX5 +, OCT2 +, BOB1 

variable, CD79a + 

● ABC phenotype: CD10 neg, BCL6 neg, IRF4/MUM1 

positive 

● CD30 +, CD15 + in few cases 

● EBV markers: LMP-1, EBER positive 

● Background scattered lymphocytes are CD8+ T 

lymphocytes 

● The rim of CD3+ T-cells at the junction of the 

lesion and normal tissue 

GENETICS 

● Clonal IG gene rearrangements 

● Clonal TR gene rearrangements 


Prognosis 

● Not malignant course 

Treatment 

● Responds well to rituximab, local radiation, and 

chemotherapy 

Figure 4 

Fig 5: CD8+ T-cells 


Chapter 3.23: DLBCL with chronic inflammation 

INTRODUCTION 

● History of long-standing chronic inflammation 

● Associated with EBV 

● Involves body cavities and narrow spaces 

● Escape of host immune surveillance due to longstanding 

chronic inflammation 

Demographics 

● Pyothorax associated lymphoma: 20-64 years 

● Second peak: 40-80 years 

● Males are more prone 

Pathogenesis 

● Chronic inflammation causes IL-10 release which 

acts as an immunosuppressive cytokine 

● IL6 released promotes the growth of lymphoid 

cells 


Table 1: Clinical presentation 

Features 

Pyothorax 

associated 

lymphoma 

DLBCL associated 

with chronic 

inflammation 

at other sites 

Age 20-64 years 40 – 80 years 

An associated 

chronic 

inflammatory 

condition 

History of 

spontaneous 

pneumothorax 

and TB effusion, 

history can be as 

long as 20 years 

ago 

Associated with 

chronic osteomyelitis, 

metallic implants, 

surgical mesh 

implants 

Site Pleural cavity Joints, bone (femur), 

periarticular soft 

tissue 

Clinical 

Morphology 

Chest pain, 

respiratory 

difficulty, 

raised serum LDH 

Mass > 10 cm 

confined to the 

thoracic cavity 

Pain, lytic lesions on X- 

ray, raised serum LDH 

Mass lesion at the site 


Microscopy 

● Diffuse infiltration of large lymphoid cells which 

simulate immunoblasts and centroblasts 

● Areas of necrosis 


Kshitija Kale 


● B-cell markers: CD20 +, CD79a + 

● In the case of plasmablastic differentiation: 

CD138, IRF4/MUM1 positive 

● CD30 may be positive 

● EBV markers: EBER positive, type III latency 

● Occasionally T-cell markers are expressed: CD2, 

CD3, CD4, CD7 

GENETICS 

● Clonal Ig gene rearrangements and 


● Majority: TP53 mutations 

● MYC amplification 

● Del TNFAIP3 

● Complex karyotype 

● Chronic inflammation via Interferon-alpha 

induces IFI27 expression 

● Downregulation of HLA class 1 expression 

● Mutations in epitopes of T-lymphocytes 

(EBNA 3A) 


Prognosis 

● Aggressive course 

● Unfavorable prognostic factors: 

‣ Poor performance status 

‣ Elevated serum LDH 

‣ Elevated alanine transaminase, urea 

‣ High clinical stage 

Treatment 

● Pleuro-pneumonectomy 

FIBRIN ASSOCIATED DLBCL 

INTRODUCTION 

● Not mass forming 

● Detected incidentally in specimens with fibrinous 

material e.g. Pseudocyst wall, hydrocoele, 

cardiovascular specimens like 

myxoma/prosthesis/fibrin thrombi / debris 

associated with metallic implants 



Microscopy 

● Fibrinous material and floating within it are 

aggregates of neoplastic cells 

● Cells are large with amphophilic cytoplasm, 

irregular nuclear folds, coarse chromatin, and 

distinct nucleoli 


● B-cell markers are expressed 

● ABC phenotype 

● EBV positive: type III latency 

PROGNOSIS 

● Favorable 


Chapter 3.24: Lymphomatoid Granulomatosis (LYG) 

INTRODUCTION 

● Angiocentric and angio-destructive 


● Predisposing conditions include 

immunodeficiency e.g. in HIV, congenital 

immunodeficiency, transplantation etc. 

● Composed of EBV + B-cells and reactive T-cells 

Demographics 

● Adult, males 

● Western countries 


● > 90% of patients: lungs are involved 

● Less commonly: brain, kidney, liver, skin 


● Constitutional symptoms: fever, weight loss 

● Respiratory symptoms 

● Rarely, CNS involvement 

● Indolent form: Asymptomatic patient with 

nodules that wax and wane 

● Aggressive form: Symptomatic, with multiorgan 

involvement 


Lung 

Macroscopy 

● Bilateral nodules of varying sizes, in the mid 

and lower lobe of lungs 

● Central necrosis and may cavitate 

Microscopy 

● Polymorphous cell infiltrate in the vessel wall 

● Angiocentricity and angiodestruction 

● Infiltrate is composed of lymphocytes, plasma 

cells, immunoblasts, histiocytes, neutrophils, 

and eosinophils 

● Background of small lymphocytes 

● EBV positive B cells are pleomorphic, resemble 

immunoblasts 

● Multinucleated forms may be seen 

● No granulomas are seen 

● Vascular manifestations: lymphocytic vasculitis, 

infarct-like necrosis, fibrinoid necrosis 

Other organs 

Kshitija Kale 


● Similar nodules are seen in the brain, kidney, 

and subcutaneous tissue 

● Skin: shows well-formed granulomas 


● B-cell markers: CD20 positive 

● CD30 positive, CD15 negative 

● EBV markers: latency type III LMP-1, EBNA2 

positive 

● Background lymphocytes CD3 positive 

GENETICS 

● Clonality of EBV observed in Southern Blot 

● More susceptibility in immunodeficiency linked 

syndromes 


Grading 

Table 1: Grading of Lymphomatoid granulomatosis 

Based on the number of EBV + cells 

Grade 

Features 

Grade 1 ● Polymorphous cell population 

● No cytological atypia 

● Focal necrosis 

● EBV + cells are < 5/HPF 

Grade 2 ● Polymorphous background 

● Occasional large lymphoid 

cells/immunoblasts 

● Necrosis is seen 

● EBV + cells are 5 – 20 /HPF 

Grade 3 ● Background inflammatory cells 

● Large atypical B-cells forming large 

aggregates 

● Extensive necrosis 

● EBV + cells are > 50/HPF, may form sheets 

Prognosis 

● Aggressive behavior 

● With EPOCH-R +/- interferon: 5-year survival is 

improved 

Treatment 

● Chemoimmunotherapy 


Chapter 3.25: Primary Mediastinal Large B-cell Lymphoma 

(PMBCL) 

INTRODUCTION 

● A category of large B-cell lymphoma arising in the 

anterosuperior mediastinum with distinct clinical, 

immunophenotypic, genotypic and molecular 

features 

● Aberrant somatic hypermutation by activationinduced 

cytidine deaminase is suggested as the 

mechanism of development 

● Differential includes classical Hodgkin lymphoma 

(CHL), diffuse large B-cell lymphoma (DLBCL) and 

B-cell lymphoma unclassifiable with features 

intermediate between DLBCL and CHL 

Demographics 

● Young adults 

● Female preponderance 


● Antero-superior mediastinum (thymus) and 

regional lymph nodes 

● Extra thoracic involvement of central nervous 

system, liver, adrenal glands, kidneys may occur 

on progression 


● Mass in the anterior mediastinum 

● Superior vena cava syndrome 

● Pleural/ pericardial effusion 

● Presence of B symptoms 

Vanya Jaitly 


● Cells have round to pleomorphic nuclei with 

abundant pale cytoplasm 

● Interstitial fibrosis often surrounds nodules of 

tumor cells 


● Pan B-cell markers positive 

● B-cell transcription factors PAX5, BOB1, OCT2, 

PU1 positive 

● CD30, IRF4/ MUM1, CD23, MAL1, PDL1/2 positive 

in the majority of cases 

● CD15, BCL2, BCL6, MYC expression is variable 

● CD54, FAS/ CD95, TRAF, REL1, TNFAIP2 positive 

● EBER negative 

GENETICS 

● Monoclonal IGH rearrangement 

● Mutations and translocations of CIITA leading 

to downregulation of MHC class II 

● Gains and amplifications of 9p24.1 (PDL locus) 

● Gains of 2p16.1 

● Mutations in TNFAIP3 causing constitutive 

activation of the NF-kappa B pathway 

● Mutations in SOCS1, STAT6, and PTPN1 leading to 

activated JAK/STAT pathway. 

● Mutations in BCL6 are common 


Lymph Node/ Extranodal sites 


Prognosis 

● Better prognosis than DLBCL and B-cell 

lymphoma unclassifiable with features 

intermediate between CHL and DLBCL 

● Extension into thoracic viscera, pleural/pericardial 

effusion and poor performance status are 

associated with poor prognosis 

Treatment 

● Intensive chemotherapy with or without 

radiotherapy 

● Diffuse to nodular effacement by medium-sized 

to large cells 


Chapter 3.26: Intravascular Large B-cell Lymphoma 

INTRODUCTION 

● Large B-cell lymphoma with selective 

growth of lymphoma cells within the lumen 

of vessels, particularly small and intermediatesized 

vessels 

Demographics 

● Rare, elderly 


● Widely disseminated in extranodal sites 

● Spares the lymph nodes 


Table 1: Patterns of clinical presentation 

Geographical 

Location 

Clinical 

manifestation 

Classic 

Hemo 

phagocytic 

associated 

Isolated 

cutaneous 

Western Asian Western 

females 

Mainly 

neurological 

or cutaneous 

Multiorgan 

failure, 

hepatosplenomegaly, 

pancytopenia 

Restriction 

to skin, 

better 

prognosis 

B symptoms Common Common Uncommon 

Nidhi Kataria 


Figure 2 

● Cytomorphology: Large cells with prominent 

nucleoli and frequent mitotic figures cells 

● Cells may be anaplastic or may be smaller in size 

● Sinusoidal involvement in liver, spleen and bone 

marrow 

Immunophenotype (Fig 3) 

● Positive for B-cell-associated antigens 

● CD5 and CD10 can be positive 


Morphology (Fig 1, 2) 

Figure 3 

GENETICS 

● Clonal rearrangement of immunoglobulin genes 

Figure 1 

● Neoplastic cells in the lumen of small or 

intermediate-sized vessels in many organs 

● Fibrin thrombi hemorrhage and necrosis may be 

present 


● Aggressive lymphoma 

● Treatment: Chemotherapeutic regimens with 

rituximab 

● Complications: CNS relapses and 

neurolymphomatosis 


Chapter 3.27: ALK Positive Large B-cell Lymphoma 

INTRODUCTION 

● Aggressive neoplasm of ALK-positive 

monomorphic large immunoblast-like B-cells 

with plasma cell phenotype 

Demographics 

● Rare, young males 

● No association with immunosuppression 


● Mostly involves lymph nodes or presents as a 

mediastinal mass 

● Can also involve extranodal sites 


● Advanced disease stage 

● Generalized lymphadenopathy 


Lymph Node 

● Diffuse infiltrate with a sinusoidal growth pattern 

● Cytomorphology: Large monomorphic 

immunoblast-like cells with round nuclei, large 

central nucleolus, and abundant cytoplasm 

● Also, show plasmablastic or atypical 

multinucleated giant cell morphology 


● Positive: 

‣ ALK: granular cytoplasmic positivity, 

indicative of CLTC-ALK fusion 

‣ Plasma cell markers (CD138, CD38, VS38, 

PRDM1, and XBP1) 

‣ Cytoplasmic immunoglobulin (IgA with light 

chain restriction) 

‣ OCT2, BOB1 (B-cell transcription factors) 

‣ EMA and IRF4/MUM1 

‣ Focal cytokeratin (in some cases) 

● Negative: 

‣ CD30 

‣ EBV, HHV8 

‣ CD45 and B-cell lineage markers (Negative or 

weakly positive) 


● ALK+ Anaplastic large cell lymphoma: T-cell 

lymphoma 

Nidhi Kataria 


● Poorly differentiated carcinoma 

● B-cell neoplasms with plasmablastic/ 

immunoblastic morphology, (ALK-negative) 

‣ Plasmablastic lymphoma (PBL) 

‣ Plasmablastic extramedullary plasmacytoma 

‣ Primary effusion lymphoma (PEL) 

‣ HHV8+ LBCL 

‣ Immunoblastic DLBCL 

Table 1: Differentiating features between ALK positive 

LBCL and anaplastic large cell lymphoma 

ALK positive LBCL ALK + anaplastic 

large cell 

lymphoma (ALCL) 

Morphology Plasmablastic or 

immunoblastic 

Variable, 

hallmark cells 

CD30 - + (100%) 

CD 20/79a/PAX5 - or weakly + - 

OCT2/BOB1 + - 

CD138 + - 

Granzyme B, 

Perforin, TIA 1 

Translocation 

ALK positivity 

IgH 

rearrangement 

Kappa/lambda 

ISH 

TCR 

rearrangement 

- + (80%) 

Mostly 

t(2;17) CLTC-ALK 

Granular 

cytoplasmic 

Monoclonal 

Monotypic - 

Polyclonal 

Mostly 

t(2;5) NPM-ALK 

Nuclear, nucleolar 

and cytoplasmic 

Polyclonal 

Monoclonal 

GENETICS 

● Normal counterpart is post-germinal center B-cell 

with plasmablastic differentiation 

● Clonal rearrangement of IG gene 

● ALK overexpression, most associated with t(2;17): 

CLTC-ALK fusion protein 

● Few cases associated with 

‣ t(2,5): ALK-NPM 

‣ Other fusion partners: SQSTM1, SEC31 


‣ Cryptic Insertion of three ALK gene sequences 

into chromosome 4q22-24 

● Complex karyotype 

● Activation of STAT3 pathway, with the expression 

of phospo-STAT3 and MYC 


● Aggressive disease, with no response to standard 

chemotherapy 

● Negative for CD20, so, unlikely to respond to 

rituximab 

● Longer survival reported in 

‣ Children 

‣ Patients with localized disease 


Chapter 3.28: Plasmablastic Lymphoma 

Nidhi Kataria 


INTRODUCTION 

● Diffuse proliferation of large neoplastic cells, 

resembling B immunoblasts or plasmablasts, that 

have CD20 negative plasmacytic phenotype 

Demographics: Adults, immunodeficiency, HIV 


● Extranodal regions of head and neck, particularly 

oral cavity, followed by gastrointestinal tract 

● Nodal involvement in 30% of post-transplant 

cases 


● Intermediate risk or high-risk International 

Prognostic Index (IPI) score 

● Paraprotein in some cases 


Morphology 

● Diffuse and cohesive proliferation of cells 

resembling immunoblasts to cells with 

plasmacytic differentiation 

● Frequent mitotic figures 

● Apoptotic cells and tingible body macrophages 

maybe present 

● Monomorphic plasmablastic cytology is most 

seen in the setting of HIV infection, in the oral, 

nasal, and paranasal sinus areas 

● Plasmacytic differentiation is seen more 

commonly in other extranodal sites and lymph 

nodes 

● EBER positivity and history of immunodeficiency 

can aid in differential diagnosis from 

plasmablastic plasma cell myeloma 


● Neoplastic cells express 

‣ Plasma cell markers (CD38, CD138, VS38c, 

IRF4/MUM1, PRDM1, XBP1) 

‣ Cytoplasmic IG (IgG) with light chain 

restriction 

‣ EMA and CD30 + CD56 in few cases 

‣ High Ki67 > 90% 

‣ EBER in situ hybridization 

● Negative or weakly positive for CD45 and B-cell 

markers. Negative for HHV8 

GENETICS 

● Clonal IGH rearrangement 

● Complex karyotypes 

● MYC translocation usually with IG gene, seen 

more commonly in EBV positive cases 


● Poor prognosis 

● MYC translocation associated with worse 

outcome in two studies 


Chapter 3.29: Primary Effusion Lymphoma (PEL) 

INTRODUCTION 

● Large B-cell neoplasm associated with the human 

herpesvirus 8 (HHV8), also called Kaposi sarcomaassociated 

herpesvirus, occurring in 

immunodeficient individuals 

● Presents as serous effusions without detectable 

tumor masses 

● Some patients secondarily develop solid tumors in 

adjacent structures such as the pleura 

● Extracavitary PEL: Rare HHV8-positive lymphomas 

indistinguishable from PEL presenting as solid 

tumor masses 

Demographics 

● Seen in states of immunodeficiency: 

‣ Young or middle-aged men who have sex with 

men and who have HIV infection and severe 

immunodeficiency 

‣ Solid organ transplant recipients 

‣ Elderly patients, both men, and women (in 

these patients, the lymphoma cells contain 

HHV8 and may lack EBV) 

● Coinfection with monoclonal EBV is common 

Etiology 

● Neoplastic cells are positive for HHV8 (Kaposi 

sarcoma-associated herpesvirus or KSHV) in all 

cases 

● Most cases are coinfected with EBV (not required 

for pathogenesis) 

● HHV8 encodes genes that provide proliferative 

and anti-apoptotic signals 

● IL6 prevents apoptosis by suppressing 

proapoptotic cathepsin D 

● PELs also express vlRF3, that leads to inefficient 

recognition and killing by T-cells 


● The most common sites are the pleural, 

pericardial, and peritoneal cavities 

● Usually, only a single body cavity is involved 

● PEL has also been reported in unusual cavities, 

such as an artificial cavity related to the capsule of 

a breast implant 

Nupur Sharma 


● Extracavitary tumors can occur in extranodal sites 

including the gastrointestinal tract, skin, lungs, and 

CNS, or can involve the lymph nodes 


● Commonly present as effusions in the absence of 

lymphadenopathy or organomegaly 

● Nearly half of the patients have pre-existing or 

develop Kaposi sarcoma, and the CD4+count is low 

● Occasionally associated with multicentric 



● HHV8-negative effusion-based lymphoma 

● Diffuse large B-cell lymphoma associated with 


● Burkitt Lymphoma with effusion 


Cytocentrifuge smear 

● Cells can be large immunoblastic, plasmablastic or 

anaplastic 

● Nuclei are large and round to more irregular in 

shape, with prominent nucleoli 

● Deeply basophilic abundant cytoplasm, with 

occasional vacuoles 

● A perinuclear hof consistent with plasmacytoid 

differentiation may be seen 

● Some cells resemble Hodgkin or RS cells 

● Mitotic figures are numerous 

● Staining for HHV8 may help differentiate from 

anaplastic large cell lymphoma 

● The appearance of cells is more uniform on 

histology 


● Positive: CD45, HLA-DR, CD30, CD38, VS38c, 

CD138, and EMA 

● Negative: Pan- B-cell markers such as CD19, CD20, 

and CD79a along with BCL6 

● Surface and cytoplasmic immunoglobulin is absent 

● Aberrant expression of T-cell markers maybe 

seen in cases of extracavitary PEL 

● Nuclei of the neoplastic cells are positive for 

HHV8-associated latent protein LANA1 (also called 

ORF73) 


● EBV-negative PELs usually occur in elderly HIVnegative 

patients from HHV8-endemic areas such 

as the Mediterranean 

● Solid tumors constituting the extracavitary variant 

of PEL have a phenotype similar to that of PEL but 

express B-cell associated antigens and 

immunoglobulins more frequently 

GENETICS 

● Clonal rearrangement and hypermutation of 

immunoglobulin genes, indicating B-cell origin 

● Some cases also have a rearrangement of TR genes 

in addition to IG genes 

● Nearly all cases of PEL contain clonal EBV; except 

the non-HIV infected population, which may be 

EBV-negative 

● HHV8 viral genomes are present in all cases 

● Deregulated MYC protein due to the activity of 

HHV8 encoded latent proteins 

● Mutations in the RAS family of genes and TP53, as 

well as rearrangements of CCND1, BCL2, and BCL6, 

are absent 

● Complex karyotypes with trisomy 12, trisomy 7, 

and abnormalities of 1q21-25 have been seen 


● Prognosis extremely unfavorable, and median 

survival is a few months 

● Treatment includes chemotherapy and/or immune 

modulation 


Chapter 3.30: HHV8 Associated Lymphoproliferative 

Disorder 

INTRODUCTION 

● HHV8 (Kaposi Sarcoma associated Herpesvirus) 

Nupur Sharma 

MULTICENTRIC CASTLEMAN DISEASE (MCD) 

Pathogenesis 


HHV8 + LPDs 

HHV8+ Multicentric 

Castleman Disease 

HHV8 + DLBCL, 

NOS 

HHV8 + Germinotropic 

LPD (GLPD) 

● Associated with Kaposi Sarcoma, PEL 

● Also, there are other rare HHV8 + lymphomas 

which are often an overlap of the above three 

broad categories 

Features HHV8 MCD HHV8 DLBCL HHV8 GLPD 

Associated 

with 

Clinical 

features 

Architecture 

Germinal 

Center 

Mantle zone 

Neoplastic 

cells 

Positively 

expressed 

Light chain 

restriction 

Immunosuppre 

ssion (HIV) 

Constitutional 

symptoms 

Lymphadeno - 

pathy 

Kaposi Sarcoma 

Effaced in the 

advanced stage 

Involution, 

hyalinization 

Proliferates and 

invades GC thus, 

concentric 

lamellated rings 

with penetrating 

venules 

Plasmablastic 

morphology 

HHV8 LANA1, cy 

IgM 

A prior MCD 

HIV infection 

EBV negative 

Profound immune 

suppression 

Effaced 

architecture 

large sheets of 

plasmablasts-like 

cells 

also, infiltrates 

into other organs 

Are IgM producing 

B-cells 

HHV8 LANA1, cy 

IgM 

EBV infection 

HIV negative 

Apparently 

healthy 

Lymphadenop 

athy 

Retained 

Replaced by 

plasmablasts 

Medium to 

large 

Plasmablastic 

cells derived 

from GC cell 

HHV8 LANA1, 

IRF4/MUM1 

restriction restriction or 

restriction 

EBER Negative Negative Positive (type 1 

latency) 

Genetics 

Polyclonal 

plasmablasts 

Monoclonal; 

unmutated IG 

genes 

Prognosis Poor Very aggressive 

disease 

IG gene 

rearrangement 

Polyclonal/ 

monoclonal 

Favorable 

IMCD (Idiopathic MCD) 

● Hyper vascular or regressed germinal center 

● Polyclonal plasmacytosis 

● HIV and HHV8 negative 

● Present with constitutional symptoms and 

hypercytokinemia 

Demographics 

● Immunosuppressed individuals 

(HIV positive or organ transplantation) 

● Endemic areas for HHV8: Sub-Saharan Africa, 

Mediterranean countries 

● Sexual transmission 

● Males are commonly infected 


● Constitutional symptoms: Fever, fatigue, night 

sweats, weight loss 

● Lymphadenopathy 

● Hepatosplenomegaly 

● Skin rash 

● Associated Kaposi Sarcoma 

● Lab findings: 

‣ Anemia 

‣ Thrombocytopenia 

‣ Raised C-reactive protein 

‣ Hypoalbuminemia 

‣ Hypergammaglobulinemia 


Lymph node and spleen (Fig 1, 2) 

● Follicles 

‣ Germinal center: involution, hyalinization 


‣ Mantle Zone: prominent, gradually invades 

within the germinal center and causes 

effacement of follicle 

‣ Onion skinning or concentric rings of mantle 

zone lymphocytes 

‣ Penetrating venules 

● Interspersed between are medium to large 

plasmablastic cells with eccentric nucleus with 

vesicular chromatin, 1-2 prominent nucleoli, 

and amphophilic cytoplasm 

● Interfollicular areas: sheets of mature plasma 

cells 

● With disease progression, plasmablasts form 

clusters and efface the architecture 

Image Courtesy: Chandra Krishnan, MD @hematogones 

Image Courtesy: Chandra Krishnan, MD @hematogones 


● Plasmablasts 

Figure 1 

Figure 2 

‣ HHV8 LANA1 positive 

‣ cyIgM with chain restriction 

‣ viral IL6 positive 

‣ EBER negative 

‣ CD20 +/-, PAX5 -, CD79a -/+, CD38 -/+, CD138 -, 

CD27 - 

● Interfollicular plasma cells are mature. Hence, 

IgM and IgA negative, LANA1 negative and have 

polytypic chain expression 

GENETICS 

● Plasmablasts are polyclonal (despite chain 

restriction) 


● Prognosis is poor 

● Therapy includes Rituximab + anti-herpes 

therapy + targeted therapy against IL6 

HHV8 POSITIVE DLBCL, NOS 

INTRODUCTION 

● Arises in the setting of MCD 

● Associated with HIV infection 

● EBV negative 

● Neoplastic cells are 

‣ Monoclonal, HHV8 infected, express IgM 

‣ Derived from IgM producing B-cells; no 

evidence of IG somatic hypermutations 


● Enlarged lymph nodes 


● Peripheral blood involvement 

● Also, liver, lungs, GIT are involved 


Microscopy 

● Lymph node and spleen: Architecture is effaced 

by sheets of plasmablasts 


‣ Cytoplasm: Amphophilic 

‣ Nucleus: Eccentric, vesicular chromatin 

‣ Nucleolus: 1 – 2 prominent nucleoli noted 


● Infiltrates of these plasmablastic cells are also 

seen in organs like liver, lungs, and GIT 


● Plasmablastic cells are 


‣ cyIgM chain restriction 

‣ CD20 +/-, PAX5 -, CD79a -/+, CD38 -/+, 

CD138 -, CD27 – 

GENETICS 

● IG gene rearrangements: Polyclonal or 

oligoclonal with somatic mutations +/- 

PROGNOSIS 

● Favorable 

● Respond well to chemotherapy or radiation 

GENETICS 

● Monoclonality + with unmutated IG genes 

PROGNOSIS 

● Aggressive 

HHV 8 POSITIVE GERMINOTROPIC 

LYMPHOPROLIFERATIVE DISORDER (GLPD) 

Introduction 

● Monotypic HHV8 germinotropic 

lymphoproliferative disorder occurring in HIV 

negative patients, but characteristically 

associated with EBV infection 

● Germinal centers are replaced by HHV8 

positive plasmablasts 

● Plasmablasts exhibit light chain restriction 


● Apparently healthy individual with enlarged 

lymph nodes 


Microscopy 

● Preserved lymph node architecture 

● Germinal center is replaced by plasmablasts 

● Occasionally, atretic follicles may be seen like 

MCD 


● Plasmablastic cells are negative for CD20, 

CD79a, CD138, BCL6, CD10; and maybe positive 

for CD3 

● HHV8 LANA1 and EBER are expressed 

● LMP1, EBNA1 are negative: Type 1 latency 

● IRF4/MUM1 positive 

● Monotypic or - chain restriction 


Chapter 3.31: Burkitt Lymphoma (BL) 

INTRODUCTION 

● Aggressive but curable lymphoma that presents 

in extranodal sites or as an acute leukemia 

● Characterized by monomorphic medium-sized 

B-cells with basophilic cytoplasm and numerous 

mitotic figures, with a MYC gene translocation 

to an IG locus 

● Subtypes: Endemic, Sporadic and 

Immunodeficiency associated 

Demographics 

Endemic BL: 

● 

Equatorial Africa and in Papua New Guinea 

(overlap with Malaria) 

● Most common childhood malignancy in these 

areas 


Sporadic BL: 

● Seen all over the world 

● Children and young adults affected 


Immunodeficiency-associated BL: 

● Seen commonly in the setting of HIV infection 

● Appears early and risk persists even posttreatment 

Etiology 

Endemic BL: 

● EBV genome is present in almost all the 

neoplastic cells 

● Pathogenesis considered polymicrobial 

● Plasmodium, arboviruses, schistosomiasis, 

HHV5 and HHV8 and plant tumor promoters 

implicated 

Sporadic BL: 

● EBV seen in some cases 

● Low socioeconomic status and early EBV 

infection associated with higher prevalence 

Immunodeficiency associated BL: 

● EBV seen in some cases 


Endemic BL: 

● Jaws and other facial bones (e.g., the orbit 

bones) involved in most of the cases 

Nupur Sharma 


● Distal ileum, caecum, omentum, gonads, 

kidneys, long bones, thyroid, salivary glands, 

and breasts frequently involved 

Sporadic BL: 

● Most cases present with abdominal masses 

● The ileocecal region is commonly involved 

● Ovaries, kidneys, and breasts may be involved 

● Breast involvement, often bilateral is 

associated with onset during puberty, 

pregnancy, or lactation 

● Retroperitoneal masses may result in spinal 

cord compression with paraplegia 

Immunodeficiency-associated BL: 

● Lymph nodes and bone marrow involved 


● Children usually report symptoms of only a 

few weeks duration due to short doubling 

time of tumors 

● Tumor burden is high 

● Most patients present at an advanced stage 

● Tumor lysis syndrome can occur due to rapid 

tumor cell death during treatment 

● Burkitt leukemia variant: Rare cases 

presenting purely as leukemia involving 

peripheral blood, bone marrow, and CNS 

● High and immediate chemosensitivity easily 

leads to acute tumor lysis syndrome 


Gross 

● Masses have a fish-flesh appearance, often 

associated with hemorrhage and necrosis 

● Adjacent organs or tissues are compressed 

and/or infiltrated 

● Nodal involvement frequent in 

immunodeficiency-associated BL 

Microscopy (Fig 1) 

● A diffuse monotonous pattern of growth 

● Medium-sized cells with squared-off borders 

and retracted cytoplasm in formalin-fixed 

tissue 

● “Starry sky” pattern due to numerous tingible 

body macrophages 


● Round nuclei, with finely clumped chromatin, 

and multiple basophilic medium-sized, 

paracentrally located nucleoli 


● Lymphoblastic Lymphoma 

● Blastoid mantle cell lymphoma 

● Prolymphocytic SLL/CLL 

● Diffuse large B-cell lymphoma 


● Aggressive but curable 

● Poor prognostic factors: Advanced stage 

disease, bone marrow, and CNS involvement, 

unresected tumor > 10 cm in diameter, and high 

serum lactate dehydrogenase levels 

Figure 1 


Positive 

● Membrane lgM with light chain restriction 

● B-cell antigens (CD19, CD20, CD22, CD79a, and 

PAX5) 

● Germinal center markers (CD10 and BCL6) 

● CD38, CD77, CD43 

● MYC 

● Ki-67 (very high, ~100%) 

● TCL in pediatric BL 

Negative 

● CD5, CD23, CD138, BCL2, TdT 

GENETICS 

● Hallmark is t(8,14), and less commonly t(2,8) and 

t(8,22) leading to translocation of MYC to the 

IGH locus, Kappa and Lambda respectively 

● Molecular pathogenesis: Burkitt lymphoma 

frequently harbors mutations in ID3, TCF3, and 

CCND3 that activate the TCF3 pathway 

● The t(8;14) translocation present in BL 

dysregulates MYC 

● Cooperation of these two pathways plays a 

crucial role in BL and eventually leads to cell 

proliferation 

Figure 2 


Chapter 3.32 Burkitt Lymphoma with 11q aberration 

Nupur Sharma 


INTRODUCTION 

● Lymphomas that resemble Burkitt lymphoma (BL) 

morphologically and phenotypically but lack MYC 

rearrangements 

● The clinical course is similar to that of BL, but only 

a few cases have been reported 

● Cases show chromosome 11q alteration 

characterized by proximal gains and telomeric 

losses: specifically, interstitial gains including a 

minimal region of gain in 11q23.2-23.3 and losses 

of 11q24.1-ter 

● They lack the 1q gain frequently seen in BL and 

have more complex karyotypes than BL 

● They also have cytological pleomorphism, 

occasionally a follicular pattern, and frequently a 

nodal presentation 

● Medium to large tumor cells with high mitotic 

index, starry sky pattern may be seen 

Table 1: Burkitt lymphoma versus Burkitt-like lymphoma 

Burkitt lymphoma 

MYC rearrangement common 

11q gains/loss absent 

1q frequently present 

Burkitt-like lymphoma 

MYC rearrangement absent 

11q gains/loss present 

1q gain not seen 


Chapter 3.33 High Grade B-cell Lymphoma 

INTRODUCTION 

● Group of aggressive, mature B-cell lymphomas 

that for biological and clinical reasons should not 

be classified as diffuse large B-cell lymphoma 

(DLBCL) or Burkitt lymphoma (BL) 

● Include two categories 

‣ HGBL with MYC and BCL2 and/or BCL6 


‣ HGBL, NOS 

HIGH GRADE B-CELL LYMPHOMA WITH MYC AND 

BCL2 AND/OR BCL6 REARRANGEMENTS 

INTRODUCTION 

● Aggressive mature B-cell lymphoma that harbors 

MYC rearrangement (at chromosome 8q24) and 

a rearrangement in BCL2 (at chromosome 

18q21) and/or in BCL6 (at chromosome 3q27) 

(except for proven follicular lymphomas and rare 

cases of B lymphoblastic leukemia/ lymphomas) 

● Double hit lymphomas: MYC + BCL2 or BCL6 


● Triple hit lymphomas: MYC + BCL2 + BCL6 


● Rearrangement of MYC, BCL2, and BCL6 should 

be detected by cytogenetic/molecular method 

like FISH 

● Not included in this category 

‣ Lymphomas with other than MYC 

translocation 

‣ Other gene translocations (CCND1) 

associated with MYC translocation 

‣ Cases with only copy number 

increase/amplification or somatic mutations, 

without an underlying rearrangement 

● Important to distinguish between double 

expressor vs. double-hit lymphomas 

● Double expressor lymphomas show 

immunohistochemical expression of MYC and 

BCL2, with the majority being ABC subtype of 

DLBCL, and necessarily do not harbor 

translocations which define double-hit 

lymphomas 

Nidhi Kataria 


● Lymphomas with a proven history of pre-existing 

or co-existent follicular lymphoma should be 

diagnosed as such (e.g., HGBL with MYC and 

BCL2 rearrangements, transformed from 

follicular lymphoma) 

Demographics 

● Elderly, M>F 


● Widespread disease with involvement of the 

lymph nodes 

● Can also involve more than one extranodal sites 

bone marrow, and CNS 


● Advanced disease, and elevated LDH 


● Morphologically, they can 

‣ Resemble DLBCL NOS (most common) 

‣ Be intermediate between DLBCL and BL 

‣ Resemble BL (but the cytoplasm is usually 

less basophilic than in BL, and cytoplasmic 

vacuoles are absent) 

‣ Have blastoid appearance mimicking 

lymphoblastic lymphoma or the blastoid 

variant of mantle cell lymphoma (negative 

for TdT and Cyclin D1) 


● Positive for B-cell markers (CD19, CD20, CD79a, 

PAX5), and GC markers CD10 and BCL6 in most 

cases and IRF4/MUM1 in few cases 

● Negative for TdT 

● Some cases lack surface immunoglobulin 

expression 

● Cases with BCL2 rearrangement have strong 

cytoplasmic BCL2 positivity, in contrast to the 

absent or weak expression of BCL2 in BL 

● Ki67 proliferation index is variable, high in cases 

that mimic BL, and can be low in cases that 

resemble DLBCL 

GENETICS 

● MYC (8q24) rearrangements as detected by 

classic cytogenetics, FISH or other molecular 


genetics test with BCL2 rearrangement (18q21) 

and /or BCL6 (3q27) rearrangement 

● MYC translocation partner can be IG gene or 

non-IG 

● Association with complex karyotype 

● Frequently associated mutations include 

‣ TP53 mutations 

‣ MYD88 mutations 

‣ TCF3 mutations 

‣ Homozygous mutations of ID3 (inhibitor of 

TCF3) 

● Cytoplasm is usually less basophilic than in BL 


● Positive: CD20, BCL6 

● Negative: IRF4/MUM1 

GENETICS 

● MYC rearrangement in some cases 


● Poor outcome, slightly better than that of 

patients with double-hit HGBL 


● Poor response to standard chemotherapy 

● Factors influencing survival: 

‣ MYC translocation partner; cases with MYC- 

IG translocation confer a worse prognosis 

‣ Tumor morphology 

‣ Extent of disease 

HIGH GRADE B-CELL LYMPHOMAS, NOS 

INTRODUCTION 

● Clinically aggressive mature B-cell lymphomas 

that lack MYC + BCL2 and/ or BCL6 

rearrangements and do not fall into the category 

of diffuse large B-cell lymphoma (DLBCL), NOS, 

or Burkitt lymphoma (BL) 

● Diagnosis made only when the pathologist is 

truly unable to confidently classify a case as 

DLBCL or BL 

Demographics 

● Elderly, Male = Female 


● Resemble BL more than DLBCL; though can show 

some differences from BL 

● Diffuse proliferation of medium-sized to large 

cells with very few admixed small lymphocytes 

and no stromal reaction or fibrosis 

● Starry-sky macrophages may be present, along 

with many mitotic figures and prominent 

apoptosis 

● Nuclear size more variable than BL 


Chapter 3.34: B-cell Lymphoma, Unclassifiable with 

Features Intermediate between DLBCL and CHL 

INTRODUCTION 

● B-cell lineage lymphomas with overlapping 

clinical, morphological and immunophenotypic 

features between CHL and DLBCL, mainly 

primary mediastinal (thymic) large B-cell 

lymphoma (PMBL) 

● Mediastinal cases are referred to as mediastinal 

gray-zone lymphoma (MGZL) and 

Non-mediastinal cases as gray-zone lymphoma 

(GZL) 

Demographics 

● MGZL: Young males, western countries 

● GZL: Older patients, less of male predominance 


● Large anterior mediastinal masses with or 

without the involvement of supraclavicular 

lymph nodes 


● MGZL: bulky mediastinal masses leading to 

superior vena cava syndrome or respiratory 

distress 

Nidhi Kataria 



● Broad-spectrum morphology 

● Within a given tumor some areas resemble CHL 

and others resemble PMBL 

● Discordance between morphology and 

immunophenotype 

● High tumor burden with sheets of pleomorphic 

tumor cells in a diffuse fibrotic stroma (PMBL 

component) 

● Cells are more pleomorphic than are in typical 

PMBL 

● The inflammatory infiltrate is sparse as 

compared to typical CHL 


● Aberrant phenotype makes a distinction 

between CHL & PMBL difficult 

● The neoplastic cells are positive for CD45 

● Cases with CHL on morphology show 

preservation of the B-cell markers, with strong 

and uniform positivity for CD20 and CD79a 

● Weak or variable CD20 positivity in a case with 

the morphology of CHL does not support 

classification as B-cell lymphoma, unclassifiable 

● Cases with PMBL on morphology show loss of B- 

cell antigens but positivity for CD30 and CD15 

● Other variably positive antigens include MAL, 

cREL, IRF4/MUM1, though these do not help in 

supporting the diagnosis 

● Also positive for p53, p63, cyclin E 

● Negative for EBV 

GENETICS 

● Clonal rearrangement of IG genes 

● Gains and amplification of JAK2, PDL1, PDL2, 

REL, MYC 

● Breaks in CIITA locus at 16p13.13 


Prognosis 


● Aggressive clinical course with poorer outcome 

● Factors associated with worse outcome: 

‣ A decrease in absolute lymphocyte count 

‣ A high content of DC-SIGN-positive 

dendritic cells 

‣ High content of tumor-associated 

macrophages 

Treatment 

● Regimens used in the treatment of CHL are less 

effective than the regimens for treating DLBCL 

● Given the CD20 positivity, the addition of 

rituximab appears to be beneficial 


Chapter 4: Journey of T 

Lymphocyte - An 

Overview 


Chapter 4.0: Journey of T-lymphocytes - An Overview 

Kshitija Kale 


Ace the Boards: Neoplastic Hematopathology ~ 110 ~

Chapter 4.0: Journey of T-lymphocytes - An Overview 

Kshitija Kale 


T lymphoblasts 

Enter thymus 

Maturation, acquisition of function, T-cells 

recognizing self peptides are eliminated 

Cortical thymocytes: Innate immunity 

Medullary thymocytes: Adaptive immunity 

● Medullary thymocytes: Initially CD4 and CD8 

double positive and then become specific for 

CD4 and CD8 

● NK cells: cytoplasmic epsilon and zeta chains 

of CD3. They express CD2, CD7, and 

sometimes CD8, but not surface CD3 

● The T-cell derived neoplasms are rare in 

adults, but are common in children 

● They include a wide category of EBV-associated 

neoplasms 

INTRODUCTION 

● T-cell leukemias/ lymphomas although rare 

form an important part of neoplastic 

hematology as they have a rapid disease 

course and poor prognosis 

● T-cell progenitors are derived from marrow 

and mature in the thymus 

● Cortical thymocytes: Express TdT, CD1a, CD3, 

CD5 and CD7, double negative for CD4 and 

CD8 

Naïve T-cells 

Secondary 

immune 

response 

Antigen 

encounter 

Secondary 

Antigen 

exposure 

Clonal 

Expansion and 

Effector 

Function 

Memory T-cells 


T-cell in Innate immunity 

T-cells in adaptive immunity 

Gamma delta T-cells 

•

Cells TH 2 TH 9 TH Reg TH 17 TFH TH 1 

Via IL 4 IL 4, 

TGF B 

Transcription STAT6 STAT6 

factor (TBX1, SMAD 

GATA3) 

Cytokines 

produced 

IL 4 

IL 5 

IL 6 

IL 10 

IL 13 

IL 9 

IL 10 

IL 21 

TGF B IL 6, TGF B IL 6 IL 12 

SMAD 

STAT3 

SMAD 

IL 10 IL 17 

1L 21 

1L 22 

STAT3 

IL 21 

STAT4 

(TBX1, GATA3) 

IFN gamma 

Acts on Eosinophils Neutrophils Macrophages 

Functions Helminthic 

infections 

allergy 

Suppress 

inflammatory 

response 

Kills 

extracellular 

pathogens 

Via CXCL13-CXCR5 interaction 

causes migration of B and T- 

cells into the germinal center 

Kills intracellular 

pathogens 

Immunophen 

otype 

Associated 

lymphoma 

PTCL, NOS 

(GATA3) 

CD25+ 

FOXP3+ 

ATLL 

(cytokines 

secreted 

activate 

osteoclasts thus 

hypercalcemia) 

ALCL 

BCL6+ 

CD10+ 

CD57+ 

CD79a+ 

CXCL13 

-Increased expression of 

CXCL13 in AITL 

-Primary cutaneous CD4+ 

small/medium T-cell LPD 

PTCL, NOS 

(TBX1) 

Nodal Extranodal Cutaneous Leukemic 

• Peripheral T-Cell 

Lymphoma, NOS 

• Angioimmunoblastic T-Cell 

Lymphoma 

• Systemic Anaplastic T-Cell 

Lymphoma (ALK-Positive, 

ALK-Negative) 

• Follicular T-Cell Lymphoma 

• Extranodal NK-Cell 

Lymphoma, Nasal 

• Intestinal T-Cell Lymphoma 

• Indolent T-Cell 

Lymphoproliferative 

Disease of GI Tract 

• Hepatosplenic T-Cell 

Lymphoma 

• Mycosis Fungoides 

• Sezary Syndrome 

• Subcutaneous Panniculitis-like 

T-Cell Lymphoma 

• Primary Cutaneous CD30+ 

Lymphoproliferative Disease 

• Lymphomatoid Papulosis 

• HTLV-1 Adult T-Cell 

Leukemia/ Lymphoma 

• T-large granular leukemia 

Lymphoma 

• Aggressive NK-Cell 

Leukemia 

• Nodal Peripheral T-Cell 

Lymphoma with TFH 

Phenotype 

• Systemic EBV T-Cell 

Lymphoma of Childhood 

• Hydroavacciniform-like 


Disease 

• Breast Implant-Associated 

Anaplastic Large T-Cell 

Lymphoma 

• Chronic 


Disease of NK Cells 

• Primary Cutaneous T-Cell 

Lymphoma 

• Primary Cutaneous CD8+ 

Aggressive Epidermotropic 

Cytotoxic T-Cell Lymphoma 

• Primary Cutaneous CD4+ T-Cell 

Lymphoma 


Chapter 5.1 T Lymphoblastic Leukemia/Lymphoma (T- 

ALL/T-LBL) 

Nupur Sharma Aakash Bhatia Akanksha Gupta 



ALL/T-LBL) 


Chapter 5: Precursor T 

and NK Cell Neoplasms 



ALL/T-LBL) 




ALL/T-LBL) 


INTRODUCTION 

● Neoplasm with blasts committed to T-cell 

lineage 

● Involves bone marrow and blood (T-ALL) or 

presents with primary involvement of the 

thymus or nodal or extranodal sites (T-LBL) 

Demographics 

● More common in adolescents than in younger 

children, M>F 

● T-LBL accounts for >80% of all LBL 


● Bone marrow and blood (T-ALL) 

● Primary involvement of the thymus or nodal or 

extranodal sites (T-LBL) 

● The skin, tonsils, liver, spleen, CNS, and testes 

may be involved 


● T-ALL: High leukocyte count, large mediastinal 

mass, lymphadenopathy, hepatosplenomegaly 

● T-LBL: Mass in the anterior mediastinum, rapid 

growth, pleural effusion 



● Blasts are variable in morphology, ranging from 

small with condensed nuclear chromatin and no 

evident nucleoli to larger blasts with finely 

dispersed chromatin and relatively prominent 

nucleoli 

● Nuclei round to irregular and convoluted 

● Cytoplasmic vacuoles may be present 

Bone Marrow 

● In T-ALL, the lymphoblasts have high N:C ratio, 

finely stippled chromatin, and inconspicuous 

nucleoli 

Lymph Node 

● In T-LBL, complete effacement is most 

common, partial effacement and nodular 

pattern are also seen 

● Mitotic figures common 

● Extensive replacement of the thymic 

parenchyma and infiltration of the surrounding 

fibroadipose tissue 


● Lymphoblasts: TdT+ and variably express CD1a, 

CD2, CD3, CD4, CD5, CD7, and CD8 

● CD7 and CD3 (cytoplasmic) are most often 

positive, but only CD3 is considered lineagespecific 

● TAL1 positive in up to half cases 

● Four stages of intrathymic differentiation 

according to the antigens expressed 

Pro-T Pre-T Cortical T Medullary T 

cCD3 + + + + 

CD7 + + + + 

CD2 - + + + 

CD1a - - + - 

CD34 +/- +/- - - 

CD4/CD8 -/- -/- +/+ Either 

Figure 1: Near-ETP ALL 


ETP-ALL/LBL (Early T-cell precursor) 

● Absent CD1a and CD8 expression 

● Absent or dim CD5 expression 

● Expression of 1 or more myeloid (CD11b, CD13, 

CD33, CD117) or stem cell (CD34, HLA-DR) 

markers 

● Note: cases with bright or uniform CD5 with 

other features of ETP-ALL are termed as “near 

ETP-ALL” 

blastic plasmacytoid dendritic cell neoplasm has 

been excluded 

GENETICS 

● Clonal rearrangements of the T-cell receptor 

almost always present 

● IGH gene rearrangements in some cases 

● Commonly involved genes: TAL1, HOX1, LMO, 

MYC, TLX1, TLX3 

● T-ALL can be divided into four distinct, nonoverlapping 

genetic subgroups based on specific 

translocations 1) TAL or LMO genes, (2) TLX1, (3) 

TLX3, and (4) HOXA genes, resulting in the arrest 

of T-cell maturation at distinct stages of 

thymocyte development 

● Del(9p), mutated NOTCH1 also common 

● Overexpression of LYL1 is seen in ETP-ALL 

PROGNOSIS 

● Higher-risk disease than B-ALL due to older age 

and higher white blood cell count 

● Associated with a higher risk of induction 

failure, early relapse, and isolated CNS relapse 

than B-ALL 

● Minimal residual disease following therapy is a 

strong adverse prognostic factor 

● ETP-ALL poorer prognosis than other T-ALL 

NK LYMPHOBLASTIC LEUKEMIA/LYMPHOMA 

● Considered a provisional entity 

● Diagnosis of precursor NK-ALL/LBL may be made 

in a case that expresses CD56 along with 

immature T-cell markers such as CD7 and CD2 

and even including cCD3, provided that the case 

lacks B-cell, and myeloid markers, TCR and IG 

genes are in the germline configuration, and 


Chapter 6: Mature T-cell 

Neoplasms 


Chapter 6.1: T-cell Prolymphocytic Leukemia (T-PLL) 

Nidhi Kataria 



Chapter 6.1: T-cell Prolymphocytic Leukemia (T-PLL) 

INTRODUCTION 

● Aggressive T-cell leukemia with the proliferation 

of prolymphocytes having post thymic T-cell 

phenotype involving peripheral blood, bone 

marrow, lymph nodes, spleen, and skin 

Demographics 

● Rare, adults 


● Peripheral blood, bone marrow, lymph nodes, 

spleen, liver, and sometimes skin 


● Hepatosplenomegaly and generalized 


● Anemia, thrombocytopenia, and lymphocytosis 

>100 X 10 9/ L 

● Skin infiltration in 20% cases and rarely serous 

effusions 

Nidhi Kataria 


● Prominent high endothelial venules infiltrated 

by neoplastic cells 

Skin 

● Perivascular and periadnexal or diffuse dermal 

infiltrates without epidermotropism 

Cytochemistry 

● Strong staining with alpha-naphthyl acetate 

esterase and acid phosphatase with dot-like 

pattern 




● Peripheral smear diagnosis showing small to 

medium-sized cells with non-granular basophilic 

cytoplasm, round, oval or irregular nuclei, visible 

nucleoli, and cytoplasmic protrusions or blebs 

Figure 1 

Courtesy: @KyleBradleyMD 

● Variants: 

‣ Small cell variant: small cell size 

‣ Cerebriform variant: irregular nuclear outline 

Bone Marrow 

● Diffuse infiltration 

Spleen 

● Dense red pulp infiltrate, invading the spleen 

capsule, blood vessels, and atrophic white pulp 

Lymph nodes 

● Diffuse infiltration mainly in the paracortical 

areas 

● Peripheral T-cells positive for 

CD2, CD5, CD7, and CD3, with weak membranous 

staining for CD3 

● CD52 (strongly positive): can be used for 

targeted therapy 

● Overexpression of TCL1, used for detecting MRD 

● S100+ in some cases 


● Negative for TdT and CD1a 

● CD4+/CD8-: most cases 

● CD4+/CD8+: some cases (exclusive to T-PLL) 

● CD4-/CD8+: few cases 

GENETICS 

● Clonal rearrangement of TCR genes 

● inv14(q11q32), most common genetic 

abnormality 

● Translocations: t(14;14); TCL1A/B-TRA and 

t(X:14); MTCP1-TRA act as initiating events 

● Abnormalities of chromosome 8, idic 8, t(8;8), 

and trisomy 8q 

● Deletion at 12p13, 22q, 11q23, amplification of 

5p, gain in MYC gene, missense mutation at 

ATM locus 

● TP53 deletion with overexpression of p53 

● Mutual exclusive mutations of JAK3, JAK1, or 

STAT5B: constitutive activation of STAT 

● Mutations of epigenetics related genes: EZH2, 

BCOR are rare 

● Association with ataxia-telangiectasia 


Prognosis 

● Poor prognosis: 

‣ Expression of TCL1 and AKT1 

‣ STAT5B mutation 

Treatment 

● Aggressive clinical course 

● Anti-CD52: Alemtuzumab 

● Stem cell transplantation after immunotherapy 


Chapter 6.2: T-cell Large Granular Lymphocytic Leukemia 

(T-LGLL) 

INTRODUCTION 

● Indolent T-cell neoplasm associated with a 

persistent increase in large granular 

lymphocytes in peripheral blood (>6 months, 

2-20 x 10 9 /L) in the absence of a clear 

underlying cause 

Demographics 

● Middle-aged to elderly 

● No sex predilection 

Pathogenesis 

● Persistent activation of the immune system by 

chronic antigen stimulation causes activation 

of a pro-survival pathway 

● High expression of FAS and FASL on tumor 

cells, but the absence of activation-induced 

cell death suggests resistance to FASmediated 

apoptosis in these cells 

● Hypothesized that elevated serum FASL levels 

in these patients lead to neutropenia 

● Dysregulation of other signaling pathways: 

MAPK, PI3K/AKT, NFKB, JAK/STAT is seen 

● Chronic stimulus → immune response → 

clonal selection → oncogenic mutations → T- 

LGLL 


● Severe neutropenia 

● Anemia >> thrombocytopenia 

● Lymphocyte count 2 – 20 x 10 9 /L (not a strict 

criterion) 

● T-LGL count >2x10 9 /L is associated with large 

clonal population; however, not required for the 

diagnosis 

● Moderate splenomegaly 

● Associated with rheumatoid arthritis: 

autoantibodies+, immune complexes+, 

hypergammaglobulinemia 

● Associated with hairy cell leukemia or CLL 

Nidhi Kataria 


● Ultrastructure of these granules: parallel tubular 

arrays and are composed of proteins like 

perforin and granzyme B 

Figure 1 

Courtesy: @KyleBradleyMD 

Bone Marrow 

● Hypo-, hyper- or normocellular marrow 

● LGL occupies

● Positive for CD2, CD3, CD8 

● −phenotype 

● Loss of CD5, CD7 seen frequently 

● CD16, CD57, CD94 (NKG2) positive in most cases 

● KIR seen in half of the cases, but CD56 is 

negative 

● Cytotoxic granule markers are expressed: TIA1, 

granzyme B, granzyme M 

GENETICS 

● Clonal TCR gene rearrangement required for 

diagnosis 

● TRG gene rearranged in all cases 

● TRB gene rearranged in cases expressing alphabeta 

TCR 

● STAT3 (SH2 domain) mutations in a subset of 

cases 

● STAT5B (SH2 domain), N642H mutations 


Prognosis 

● Indolent course, non-progressive 

● Cytopenia (neutropenia) is a major cause of 

morbidity 

● Rarely spontaneous remission is noted 

● STAT3 mutations: No difference in survival with 

STAT3 negative cases, but STAT3 mutations are 

associated with more symptomatic disease and 

treatment failure 

● 

STAT5B and N642H mutations are associated 

with an aggressive course 

Treatment 

● Immunosuppressants are helpful 

● Splenectomy 

● Newer approaches inhibiting the STAT3 or 

STAT5B pathway 


Chapter 6.3: Chronic lymphoproliferative disorder of NKcells 

(CLPD-NK) 

Kshitija Kale Vanya Jaitly Akanksha Gupta 

INTRODUCTION 

● Provisional entity 

● Rare indolent disorder with a persistent 

increase in NK cells in peripheral blood in the 

absence of an underlying cause (>6 months, ≥2 

x 10 9 /L) 

● No association with EBV infection 

● Associated with autoimmune diseases, viral 

infections 

● Dasatinib therapy can infrequently cause a 

clonal increase in NK cells 

● STAT3 SH2 mutations seen in a subset of cases 

Demographics 



● Usually asymptomatic 

● May present with cytopenias, 

lymphadenopathy, hepatomegaly, skin lesions 

GENETICS 

• Activating mutations in the STAT3 SH2 domain in a 

subset of cases 

• X-chromosome inactivation 

PROGNOSIS 

Fate of CLPD-NK 

•Spontaneous remission 

•Lymphocytosis and worsening 

cytopenias, suggestive of disesase 

progression 

•Transformation to aggressive NK cell 

disorder 



● Circulating NK cells and lymphocytosis noted 

● NK cells are: 

‣ Intermediate sized 

‣ Basophilic cytoplasm with azurophilic granules 

‣ Round nucleus 

‣ Condensed chromatin 

Bone Marrow 

● Intrasinusoidal and interstitial infiltration by NK 

cells might be present 


● Positive: cCD3-epsilon, CD16, CD56 (weak), 

cytotoxic markers: TIA1, granzyme B/M 

● CD8: uniformly expressed, CD94 is bright 

● Negative: CD2, CD7, CD57, CD161 

● KIR (killer cell Ig-like receptor) is CD158 

(shows a restricted isoform pattern) 

CD158a 

CD158b 

CD158e 

Isoforms of CD158 (KIR) 

Expressed 

Not Expressed 


Chapter 6.4: Aggressive NK-cell leukemia 


INTRODUCTION 

● EBV-associated 

● NK cell proliferation 

● Highly aggressive clinical course 

Demographics 

● Asians, young-middle aged adults 

Site of involvement 

● Peripheral blood, marrow, liver, spleen 


● Fever 

● Cytopenia 

● Raised LDH 


● Effusions 

● FASL can be demonstrated in the serum of some 

patients 

● Complications: multiorgan failure, 

coagulopathies, hemophagocytic syndrome 

Bone Marrow 

● Tumor cells infiltrate the marrow 

● Markedly pleomorphic 

● Admixed with macrophages exhibiting 

hemophagocytosis 

Organs 

● Infiltrate composed of monotonous round cells 

● Areas of necrosis seen 

● Angioinvasion may be seen 

● Apoptotic bodies may or may not be seen 


● Positive: CD2, cCD3 epsilon, CD56, CD16, CD11b 

● Negative: sCD3, CD57, CD2, CD7, CD45 

● FASL is expressed by tumor cells 

Figure 2 


Peripheral Smear (Fig 1) 

● >80% of the circulating cells are neoplastic 

● Cells are: 

‣ Large 

‣ Abundant granular cytoplasm (Fig 1) 

‣ Atypical round nucleus 

‣ Irregular nuclear folds 

‣ Vesicular chromatin 

‣ Prominent nucleoli 

Figure 1 

CD56 

CD3 

Courtesy: Sandeep Rao, MD, DM; @SandeepHemat 

GENETICS 

● TCR genes germline 

● EBV associated (85-100% cases) 

● Del 6q 

● Del 11q 

● Loss of chr 7p, 17p 

● Gain of 1p 

Courtesy: @SandeepHemat 

PROGNOSIS 


● Median survival is few months 

● Poor response to chemotherapy 


Chapter 6.5: EBV-positive T-cell and NK-cell 

lymphoproliferative diseases of childhood 

Kshitija Kale 


Table 1: EBV-associated T-cells and NK-cells proliferations 

Pediatric and adolescents 

• EBV positive HLH 

• Chronic active EBV infection (CAEBV) 

• CAEBV; cutaneous severe mosquito 

bite allergy 

• CAEBV; cutaneous hydroavacciniform-like 

proliferative 

disorder 

• CAEBV, systemic 

• Systemic EBV-positive lymphoma 

Adults 

• Aggressive NK-cell leukemia 

• Extranodal NK/T-cell lymphoma, 

nasal type 

• Nodal PTCL, EBV positive 

Table 2: EBV-associated T-cells and NK-cells proliferations in Pediatric and Adolescent Age Group 

Disease Clinical features Morphology Immunotype Prognosis 

EBV associated 

HLH 

Fever, splenomegaly, cytopenia BM, spleen, LN: hemophagocytosis+ CD8 

T-cell clonality 

Self-limiting 

EBV DNA/RNA in serum 

EBV+ T-cells seen 

observed 

HLH 2004 protocol 

Hyperbilirubinemia, 

hyperferritinemia 

CAEBV, 

Cutaneous; 

severe 

mosquito bite 

allergy 

Fever, lymphadenopathy, 

hepatosplenomegaly 

Hepatic dysfunction 

Skin reaction to mosquito bite: 

erythema, ulcer, scars 

Skin: epidermal ulceration, bullae 

Dermis shows polymorphic infiltrate 

with angiodestruction 

Polymorphous infiltrate: atypical cells 

+ reactive inflammatory cells 

cCD3, CD30 

CD56, TIA1, 

Granzyme B 

Reactive T-cells: 

CD4/CD8 + 

Long course 

Frequent 

recurrences, progress 

to aggressive 

lymphoma 

High Serum IgE, EBV DNA 

CAEBV, 

Cutaneous; 

Hydroavacciniform 

(HV)-like LPD 

Vesicles, crusting, scars 

Fever, lymphadenopathy, 

hepatosplenomegaly: in severe HV 

Intraepidermal vesicles, reticular 

degeneration 

Deep dermal infiltrates up to subcutis, 

involves adnexal structures 

CD8, CCR4, 

CD30, gammadelta 

phenotype 

EBV – LMP1: Neg 

Recurrent lesions 

After 10-15 years 

progress to CAEBV, 

systemic 

CAEBV, 

Systemic 

IM-like illness for >3 months 

EBV DNA > 10 2.5 copies/mg 

Organ involvement 

Tissue demonstration of EBV RNA or 

viral proteins 

Skin lesions +/- 

Liver: sinusoidal infiltrates 

Spleen: white pulp atrophy 

LN: paracortical and follicular 

hyperplasia, focal necrosis, small 

granulomas 

BM: sinus histiocytosis and 

erythrophagocytosis 

Variable 

T-cell type, 

NK-cell type, 

Both. 

CD4 > CD8 

Indolent course 

Age >8 years, altered 

liver function and 

CD4 cells suggestive 

of poor outcome 

Systemic EBV 

positive 

lymphoma 

Fever, malaise, LN+, HS+, multiorgan 

failure, sepsis 

Pancytopenia, raised LDH 

Neoplastic cell infiltration into liver, 

spleen, BM, LN with 

erythrophagocytosis 

CD3, CD2, TIA1, 

CD8 

CD56 neg 

Mortality days to 

weeks 


Table 3: EBV-associated T-cells and NK-cells proliferations in Adults 

Disease Clinical features Morphology Immunotype Prognosis 

Aggressive 

NK cell 

leukemia 

Fever, cytopenia, 

HS+, effusions, multiorgan 

failure 

CD2, cCD3, CD16, 

CD56, CD11b, FASL 

Aggressive 

Nodal PTCL, 

EBV positive 

Extranodal 

NK/T cell 

lymphoma, 

nasal type 

Elevated serum LDH 

PS: >80% circulating 

tumor cells 

Elderly; associated with 


Mass lesion in nose 

causing structural defect, 

epistaxis, nasal 

obstruction 

May disseminate to 

adjacent structures and 

skin. 

PS: large cells, abundant granular 

cytoplasm, atypical round nucleus, 

irregular folding, vesicular chromatin, 

prominent nucleoli 

Infiltrates in BM and other organs with 

necrosis, angioinvasion, apoptosis 

Monomorphic infiltration 

No necrosis or angioinvasion 

Extensive mucosal ulceration +/- 

pseudoepitheliomatous hyperplasia 

Underlying tumor infiltrate with 

angiocentricity, angiodestruction, 

necrosis 

Tumor cells: variable sizes, coarse 

chromatin, granules with admixed 

inflammatory cells 

CD5, CD57, sCD3, 

CD2, CD7, CD45: neg 

CD45RO, CD2, cCD3, 

CD56, cytotoxic 

markers, CD30, 

MATK, FAS, CD25, 

HLADR 

CD5, sCD3, CD4, 

CD8, TCR: Neg 

Median survival: 2 

months 

Poor response to 

chemo 

Higher grade (>40% 

transformed cells) 

bad prognosis 

Improved survival 

with intense 

radiotherapy 

SYSTEMIC EBV POSITIVE T-CELL LYMPHOMA OF 

CHILDHOOD 

INTRODUCTION 

● Life-threatening 

● Shortly after EBV infection 

● Rapid progression 

● Multiorgan involvement 

● Sepsis 

● High mortality within days-to-weeks 

Demographics 

● Asia, Japan, Taiwan, China, Mexico, South, and 

Central America 


● Involves multiple organs 

● Fever of acute onset 

● General malaise 

● Viral respiratory illness 



● Liver failure 

● Labs: 

‣ Pancytopenia 

‣ Altered LFTs 

‣ Abnormal EBV serology 

‣ Raised LDH 


● Neoplastic cells are medium to large-sized with 

irregular hyperchromatic nuclei and frequent 

mitotic figures 

Liver 

● Sinusoidal and portal infiltration 

● Cholestasis, steatosis, necrosis +/- 

Spleen 

● White pulp: depleted 

● Red pulp: congested 

Lymph Node 

● Architecture is preserved 

● Paracortical expansion 

Ace the Boards: Neoplastic Hematopathology ~ 128 ~

● Sinus histiocytosis +/- 

● Erythrophagocytosis +/- 

Bone Marrow 

● Histiocytic hyperplasia 

● Erythrophagocytosis 



● CD56 is negative 

● TIA1 is expressed 

GENETICS 

● Monoclonal arranged TR genes 

● EBV: type A-wild type or one with 30 bp deleted 

product of the LMP1 gene 

● EBER-ISH positive 


Prognosis 

● Very aggressive 

● Mortality within days to weeks 

Treatment 

● Etoposide + dexamethasone followed by a 

hematopoietic stem cell transplant 

CAEBV SYSTEMIC FORM 

INTRODUCTION 

Diagnostic Criteria for CAEBV, Systemic Form 

• Infectious mononucleosis-like symptoms for >3 

months 

• Increased EBV-DNA in serum >10 2.5 copies/mg 

• Organ involvement demonstrated by microscopic 

examination 

• EBV RNA/ viral protein demonstrated in tissues 

• No known malignancy/immunodeficiency / 

autoimmune disease 

Various forms of disease: 

A1 A2 A3 

Polymorphic 

Polyclonal 

B 

Polymorphic 

Monoclonal 

Monomorphic 

Monoclonal 

Monomorphic and monoclonal with a 

fulminant clinical course 

● Pathogenesis lies in an altered T-cell response 

against EBV infection 

Demographics 

● Japan, Korea, Taiwan, China 

● Rare in adults, if present disease course is 

aggressive 


● Infectious mononucleosis-like illness: fever, 

hepatosplenomegaly, lymphadenopathy 

● Skin rash, diarrhea, uveitis 

● Lab: 

‣ Pancytopenia 

‣ Abnormal LFTs 

‣ IgG against EBV viral capsid antigen (high 

titer) 

‣ EBV DNA > 10 2.5 copies/mg 

● Complications: 

‣ Hemophagocytic syndrome 

‣ Coronary artery aneurysm 

‣ Hepatic failure 

‣ Interstitial pneumonia 

‣ CNS involvement 

‣ GI perforation 

‣ Myocarditis 

‣ < 20% cases progress to NK/T-cell 

lymphoma or aggressive NK-cell leukemia 


Liver 

● Sinusoidal and portal infiltration 

Spleen 

● White pulp: atrophy 

● Red pulp: congestion 

Lymph Node 

● Paracortical hyperplasia 

● Follicular hyperplasia 

● Focal necrosis 

● Small epithelioid granuloma 

Bone Marrow 

● Sinus histiocytosis 

● Erythrophagocytosis 



● Variable. T-cell markers / NK-cell markers / 

both can be expressed 


GENETICS 

● TR gene is clonally arranged 

● Somatic mutation in the perforin gene 

PROGNOSIS 

● Variable prognosis, indolent clinical course 

● Age > 8 years, altered liver function and CD4+ 

T-cells point towards a poor outcome 

CAEBV, HYDROA VACCINIFORME-LIKE 

LYMPHOPROLIFERATIVE DISORDER 

INTRODUCTION 

● Long clinical course 

● Fever 



● Extensive skin lesions 

Demographics 

● Children approx. 8 years old 

● Boys 

● Natives of Asia, South, and Central America, 

Mexico 


Classic HV 

vesicles, crusts, 

scars 

Presentation 

Severe HV 

HV-like T-cell 

lymphoma 

● Presents with swelling of lips, face, eyelids 

● Crusted vesicles, papules with umbilication 


● CD8, CCR4, CD30 positive 

● Gamma-delta phenotype 

● Few cases express CD56 

GENETICS 

● TR gene clonal rearrangements 


● Monoclonal EBV 


Prognosis 

● Recurrent skin lesions 

● After many years, may progress to CAEBV, 

systemic 

Treatment 

● Conservative approach 

● In advanced cases, stem cell transplant can be 

considered 

CAEBV CUTANEOUS, MOSQUITO BITE ALLERGY 

INTRODUCTION 

● High fever 

● Intense local skin reaction to a mosquito bite 

● Erythema, bulla, ulcer, necrosis, scarring 

Demographics 

● Very rare, children around 6 years of age 

● In countries: Japan, Taiwan, China, Korea, 

Mexico 


Pathogenesis and Clinical Presentation 

Skin biopsy: 


● cCD3, CD30, CD56 positive 

● TIA1, granzyme B positive 

● Reactive T-cells express CD4/CD8 

● LMP1 is rarely positive 


Peripheral Smear: NK-cell lymphocytosis 

GENETICS 

● Monoclonal EBV NK-cells: clonal expansion 

● EBER-ISH ++ 

● LMP1 + 

PROGNOSIS 

● Variable 

● Can be indolent/aggressive 


Chapter 6.6: Adult T-cell leukemia/lymphoma (ATLL) 


INTRODUCTION 

● Mature T-cell neoplasm composed of circulating 

highly pleomorphic leukemic cells 

● Strongly associated with HTLV-1 infection 

● Endemic in south western Japan, Caribbean, and 

parts of central Africa 

Demographics 

● Adults with slight male preponderance 

● Viral exposure early in life, long latency before 

development of disease 

● Transmission through breast milk and blood 

products 

Etiopathogenesis 

● Viral receptor – neuropilin 1 

● Clonal integration of HTLV-1 genome is seen in 


● Transcriptional activation is through p40 tax 

viral protein 

● HBZ (HTLV-1 basic leucine zipper factor) and 

multiple genetic lesions play a role in 

oncogenesis 

● DNA hypermethylation leads to disease 

progression 


● Widespread nodal, peripheral blood and 

systemic [skin (most common), spleen, liver, 

lungs, CNS, GIT] involvement 


Table 1: Variants of ATLL 

Incidence 

Acute Lymphomatous Chronic SM 

Most 

Common 

PB involvement + - + + 

WBC counts 

Skin lesions 

High, 

Increased 

eosinophil 

Rash, 

papules, 

nodules 

Normal High Normal 

Rash, papules, 

nodules 

Rash + 

Lymphadenopathy Diffuse + Mild - 

Hypercalcemia + +/- - - 

Systemic illness, 

Immunodeficiency 

SM = Smoldering 

+ - - - 


● Marked cytological and nuclear pleomorphism, 

blastoid cells and bizarre cells with multilobed 

nuclei 

● Tumor cells resemble normal lymphocytes in 

chronic/smoldering variants 

● Early ATLL in the node may resemble Hodgkin 

lymphoma with diffuse paracortical infiltration 

by tumor cells along with B-cell derived RS-like 

cells which are EBV+ and CD30+ (owing to 

associated immunodeficiency) 

● Peripheral blood – Flower cells 

● BM – Shows patchy involvement and 

osteoclastic activity, sinusoidal infiltration, and 

background eosinophilia 

● Skin – Epidermal microabscesses, dermal 

perivascular involvement, and nodules are seen 

Picture credits: Katelyn Dannheim, MD (@KDannheimMD) 


Figure 1 

Figure 2 



● Positive: CD2, CD3, CD5, CD4, CD25, CD30 

(transformed cells), CCR4, FOXP3 (few cells) 

● Negative: CD7, CD8, ALK 

CD4 

CD8 


● Depends on age, clinical variant, performance 

status, serum calcium and LDH levels 

● Mortality is usually due to opportunistic 

infections and life-threatening hypercalcemia 

Figure 3 

CD2 

CD7 


Figure 4 


Chapter 6.7: Extranodal NK/T-Cell Lymphoma, Nasal Type 


INTRODUCTION 

● Vascular damage: angiocentric; angiodestructive 

● Prominent necrosis and tissue destruction 

● Cytotoxic phenotype 

● Association with EBV: 

‣ Type II latency 

‣ 30 bp deletion at LMP1 gene 

● Strong association with immunosuppression 

Demographics 

● Asians, Mexicans 

● Adult males 


● Upper aerodigestive tract: nasal cavity/ 

nasopharynx/ paranasal sinuses/ palate 

● Skin, soft tissue, GIT, testis 

● Rarely, intravascular involvement in skin and GIT 


● Nasal lesions 

● In some cases, admixed inflammatory cells 

are also seen 

Figure 1 

Figure 2 

● Extranasal lesions 

‣ Skin: nodules which can ulcerate 

‣ GIT: perforation and bleeding 

‣ Systemic symptoms: fever, malaise, weight 

loss 

Figure 3 


Microscopy 

● Mucosa: ulceration with adjacent 

pseudoepitheliomatous hyperplasia 

● Tumor infiltrates are diffuse, angiocentric, and 

angiodestructive 

● Areas of necrosis+, apoptotic bodies 



● Positive: CD2, CD56, CD43, CD45RO, cyCD3, 

cytotoxic markers, HLA-DR, CD25, FAS, FASL 

● CD5, CD8 may be expressed 

● CD30 positivity in some cases 

● MATK (megakaryocyte-associated tyrosine 

kinase) expressed 

● EBV is almost always demonstrated 

● Usually negative: CD4, CD8, CD16, CD57 

CD2 

CD3 

ENCODING FUNCTION 

RNA helicase 

JAK/STAT signaling 

Tumor suppressor 

gene 

Oncogenes 

Epigenetic modifiers 

Cell cycle regulators 

Apoptosis regulator 

DDX3X 

GENES ENCODING 

STAT3, STAT5B, JAK3, PTPRK 

Tp53, MGA, PRDM1, ATG5, AMI, 

FOXO3, HACE1 

RAS, MYC 

KMT2D/ MLL2, ARID1A, EP300, 

ASXL3 

CDKN2A, CDKN2B, CDKN1A 

FAS 

CD4 

CD43 

CD8 

CD56 

PROGNOSIS 

● Previously patients had low survival; now it has 

improved due to intense chemotherapy 

● A poor outcome with these features: 

‣ Advanced stage III/IV 

‣ Unfavorable IPI, bone/skin invasion 

‣ High Ki67 

‣ Higher grade 

CD25 

Granzyme B 

CD57 

EBER 

Figure 4 

GENETICS 

● Clonal TR rearrangements in a subset of cases 

● Del(6)(q21q25), i(6p10) 

● A gain of chromosome 2q 

● Loss of 1p, 6q, 4q, 5q, 7q, 11q, 15q 

● Recurrent mutations are seen in: 


Chapter 6.8: Intestinal T-Cell Lymphoma 


PRECURSORS TO EATL 

REFRACTORY SPRUE/REFRACTORY COELIAC DISEASE 

● Persistent GI symptoms 

● Abnormal mucosa (raised IEL) 

● Despite a strict gluten-free diet for more than 

6 – 12 months 

● Exclude: bacterial overgrowth, microscopic 

colitis, lymphoma, CVID, autoimmune 

enteropathy 

Table 1: Types of refractory sprue 

Type 1 Type 2 

Most common 

Milder disease 

Normal IEL which 

express CD8, 

sCD3, TCR 

Risk of EATL is 

low 

Good survival 

Less common 

Ulcerated mucosa, 

severe villous 

atrophy, lamina 

propria: lymphoid 

aggregates 

(cryptic EATL or 

EATL-in-situ) 

IEL show an aberrant 

absence of CD8, 

CD3, TCR 

Severe symptoms, 

profound 

malnutrition, skin 

lesions 

Altered IL5 

expression 

 

promotes survival of 

aberrant IEL 

 

additional genomic 

instability 

a gain of 1q22, loss 

of p16, LOH at 9p 

 

evolution into EATL 

Risk of EATL is high 

Low survival 

INTESTINAL T-CELL LYMPHOMA 

Table 2: Types of Intestinal T-cell lymphoma 

Type 1 (EATL) 

Type 2 (MEITL) 

• Enteropathy associated 

T-cell lymphoma (EATL) 

• Associated with celiac 

disease 

• North Europeans 

• Polymorphic population 

of cells, CD8-, CD56- 

• phenotype 

• Aggressive disease 

course in adults 

• Associated with 

extranodal NK/T-cell 

lymphoma, nasal type 

• Monomorphic 

epitheliotropic intestinal T- 

cell lymphoma (MEITL) 

• Not associated with celiac 

disease 

• Asians and Hispanics 

• Monomorphic population of 

cells, CD8+, CD56+ 

• phenotype 

• Aggressive disease course in 

adults 

• MATK is characteristically 

expressed 

• Gain of 8q24 (MYC gene) 

• Mutations in STAT5B, SETD2 

ENTEROPATHY ASSOCIATED T-CELL LYMPHOMA (EATL) 

INTRODUCTION 

● Neoplasm characterized by intraepithelial T-cells 

● Strongly associated with celiac disease 

● Marked cellular pleomorphism with neoplastic 

lymphocytes and chronic inflammatory cells 

● Adjacent intestinal mucosa shows villous 

atrophy, crypt hyperplasia, and increased IELs 

Demographics 

● Elderly male, European 

● Genotypes: HLA DQA1*0501, HLA DQB1*0201 

● Evidence of celiac disease 

‣ Anti-endomysial antibodies 

‣ HLA DQ2, HLA DQ8 alleles positive 

‣ Gluten sensitivity positive 

‣ Gluten-free diet is protective 


● Jejunum, ileum, followed by colon and stomach 

● Abdominal pain, diarrhea, anorexia, fatigue, 

weight loss 

● Intestinal obstruction (early satiety, nausea, 

vomiting) → intestinal perforation 

● Raised LDH, low albumin, low hemoglobin 

● Endoscopy: ulcer or mass or stricture 

● Staging done by CT scan. Most patients are 

already advanced stage 

● Intraabdominal LN are affected in 1/3 cases 

● Other sites involved: bone marrow, lung, 

mediastinal LN, liver, skin, CNS 


Macroscopy 

Figure 1 

Picture credits: Cory Nash, MS, PA 


● Ulcerating nodule or plaques or strictures 

● Uncommonly presents as an exophytic mass 

● Adjacent mucosa: loss of folds 

● Mesentery and mesenteric LNs involved 

Microscopy 

Intestinal mucosa 

● Neoplastic cells are medium to large-sized 

(anaplastic morphology) 

‣ Cytoplasm: moderate, pale 

‣ Nucleus: round to angulated 

‣ Chromatin: vesicular 

‣ Nucleoli: prominent 

● Angiocentric, angioinvasion 

● Admixed inflammatory cells: histiocytes, 

eosinophils 

● Epitheliotropism: IEL are tumor cells 

● Adjacent mucosa: normal or celiac disease-like 

morphology 

Figure 2 

Lymph Node 

● Sinusoidal or paracortical infiltration 

● Necrosis +/- 

● LN cavitation (LN replaced by lymph fluid) 



● CD5, CD4, CD8, CD56 negative 

● CD8 expressed in patients with refractory sprue 

● Cytotoxic markers: TIA1, granzyme B, perforin 

expressed 

● CD30 has variable expression 

GENETICS 

● Clonal rearrangements: TRB, TRG genes 

● Gain in 9q34 (NOTCH1, ABL1, VAV2) 

● Gain in 1q, 5q 

● Loss of 9p (CDKN2A/ 2B), 17p (TP53) 

● Loss of p16 expression 

● Del 16q12.1 

● Mutations in JAK-STAT signaling 

PROGNOSIS 

● Poor outcome 

● Low serum albumin, malnutrition 

● Prognostic scales used include PIT (prognostic 

index for TCL), EPI (EATL prognostic index) 

MONOMORPHIC EPITHELIOTROPIC INTESTINAL T-CELL 

LYMPHOMA (MEITL) 

INTRODUCTION 

● Not associated with celiac disease 

● No history of malabsorption 

● Intense infiltration of the epithelial lining by 

monomorphic (no admixed inflammatory cells) 


● No necrosis 

Demographics 

● Asians, Hispanics 

● Males 


● Jejunum is often involved 

● Abdominal pain, obstruction→perforation, 

weight loss, diarrhea, GI bleed 


Macroscopy 

● Tumor mass or ulceration 

● Diffuse involvement of mucosa 

● Mesenteric LNs are often affected 

Microscopy 

● Villous architecture distorted 

● Villi are expanded with tumor cells 

● Prominent epitheliotropism 


● Neoplastic cells are uniform, monomorphic 

‣ Medium-sized 

‣ Cytoplasm: scant, pale rim seen 

‣ Nucleus: round and regular 

‣ Chromatin: fine 

‣ Nucleoli: inconspicuous 

Figure 3 



● phenotype 

● TIA1 is expressed, not granzyme B or perforin 

● CD20 aberrantly positive 

● CD5 negative 

● Megakaryocytic associated tyrosine kinase 

(MATK) is characteristically positive 

CD3 

CD5 

CD3 

CD7 

CD3 

CD8 

Figure 4 

CD56 

CD3 

TCR-Delta 

TIA-1 

CD4 

Figure 5 

Figure 6 

GENETICS 

● TR gene clonal rearrangements 

● Amplification of 8q24 (MYC) 

● Gain of 9q34.3, 1q32.3, 4p15.1, 5p34, 7q34, 

8p11.23, 9q22.31, 9q33.2, 12p13.31 

● Loss of 7p14.1, 16q12.1 

● Activating mutations in STAT5B 

● Mutations in JAK3, GNA12 

● SETD2 mutations 


● EBV is negative; however, if positive is 

suggestive of NK/T-cell lymphoma. Background 

B-cells may be EBV infected 

PROGNOSIS 

● Poor 

INTESTINAL T-CELL LYMPHOMA, NOS 

● None of the above two categories are met 

● Clinically aggressive 

● Usually considered in cases of inadequate 

sampling. The mucosa is not entirely visible or 

immunophenotyping is erratic: TCR are silent, 

but cytotoxic phenotype+ 

INDOLENT T-CELL LYMPHOPROLIFERATIVE DISORDER 

OF GASTROINTESTINAL TRACT 

INTRODUCTION 

● Clonal 

● Lamina propria is infiltrated by neoplastic cells, 

but epithelium is spared 

● Small intestine and colon are involved 

● Indolent course 

Demographics 

● Adults, men > women 

● May have a history of Crohn’s disease 


● Small bowel, colon is involved 

● Less common sites: oral cavity, esophagus 

● Abdominal pain, diarrhea, vomiting, dyspepsia, 

weight loss, mesenteric lymphadenopathy 

● Muscularis mucosa and submucosa are 

infiltrated 

● Lymphocytes are monomorphic, round mature 

● No admixed inflammatory cells 

● Epithelioid granuloma: focally present 


● CD3, CD8, CD4, TIA1, CD103 are expressed 

● Granzyme B is negative 

● phenotype 


● Ki67

Chapter 6.9: Subcutaneous Panniculitis-Like Lymphoma 


INTRODUCTION 

● phenotype, cytotoxic T-cells 

● Involves subcutaneous tissue 

● Apoptosis and necrosis are a feature 

● Not associated with EBV 


Demographics 

● Any age group 

● Females > males 

● Few associated with autoimmune diseases 


● Subcutaneous nodules and plaques 

‣ Variably sized 

‣ Extremities and trunk 

‣ Maybe ulcerated 

● Hepatosplenomegaly, hemophagocytosis 

● Labs: cytopenia and elevated LFTs 

Figure 2 

● Cells are of uniform size with irregular 

hyperchromatic nuclei with a rim of cytoplasm 

● Reactive histiocytes 

● Karyorrhexis 

● Vascular invasion 



Skin 

Fig 3: CD8 

● phenotype 

● CD8+, BF1+ 

● Cytotoxic granule markers: granzyme B, 

perforin and TIA1 are expressed 


● CD123 is not expressed in tumor cells. Expressed 

in plasmacytoid dendritic cells 

Figure 1 

GENETICS 

● TR clonal rearrangements 

PROGNOSIS 

● Good, Excellent 5-year survival 


Chapter 6.10: Mycosis Fungoides (MF) 

INTRODUCTION 

● Primary cutaneous TCL with epidermotropism 

● Small-to-medium-sized T-lymphocytes with a 

cerebriform nuclei 


Table 1: Key definitions 

Patch 

Plaque 

Tumor 

Abnormal 

peripheral LN 

Sezary cells 

Skin lesion with no elevation or induration 

Skin lesion with elevation or induration 

Solid or nodular lesion >1 cm, having 

depth or vertical growth 

Palpable LN, >1.5cm in size, 

firm/fixed/irregular/clustered 

Lymphocytes with hyperconvoluted 



Skin 

● Epidermotropism, Pautrier’s microabscess 

● If >25% of cells are large blastic: it is labeled as 

histological transformation 

LN: Paracortical expansion by histiocytes and FDCs 

Patch Plaque Tumor 

Early Lesions 

‣ Superficial lichenoid infiltrate (band-like) 

‣ Fibrosis of papillary dermis 

‣ Epidermotropism 

‣ Tumor cells colonize at the base of 

epidermis, appearing as haloed cells 

‣ Pronounced epidermotropism 

‣ Pautrier’s microabscesses: clusters of 

atypical cells in epidermis 

Tumor stage 

‣ Epidermotropism lost 

‣ Diffuse dermal infiltrates 

Erythrodermic 

stage 

Figure 1 

Picture credits: Silvija Gottesman, MD 

● Neoplastic atypical cells: small to medium-sized 

● Nucleus: indented, cerebriform, with nuclear 

pleomorphism 

Demographics 

● Variable age group, M>F 

● Higher incidence in Black population 

● Associated with environmental toxins, obesity, 

smoking history 


● Sun-protected skin areas 

● Extracutaneous sites: LN, liver, spleen, lungs, 

blood 


● An indolent, slow progression of lesions through 

the above stage 


● CD2, CD3, CD4, CD5: positive 

● CD7, CD8: negative 

● TCR β Positive, γ Negative 

● CLA (cutaneous lymphocyte antigen) is 

expressed 

● Partial CD30 expression may be seen 

● Cytotoxic granule associated proteins are 

expressed in advanced lesions 


Figure 2 

IA T1, N0, M0, B0-1 IB T2, N0, M0, B0-1 

IIA T1-2, N1-2, M0, B0-1 IIB T3, N0-2, M0, B0-1 

H&E 

CD3 

IIIA T4, N0-2, M0, B0 IIIB T4, N0-2, M0, B1 

IVA T1-4, N0-2-3, M0, B2 IVB T1-4, N0-3, M1, B0-2 

Table 3: variants of MF 

Staging and Variants 

Table 2: Staging for mycosis fungoides as per International Society for 

Cutaneous Lymphoma (ISCL) and the European Organization for 

Research and Treatment of Cancer (EORTC) 

T1 

T2 

T3 

T4 

CD4 

CD5 

Skin Lymph Node Viscera Blood 

Patch or 

plaque 

occupying 

10% of 

BSA 

Tumor 

≥1 lesion, 

≥1 cm in 

diameter 

Confluent 

erythema 

>80% of 

BSA 

N0 

N1 

N2 

N3 

No 

abnormal 

LN 

Abnormal 

LN with 

Dutch 

grade 1 

Abnormal 

LN with 

Dutch 

grade 2 

Abnormal 

LN 

with Dutch 

grade 3 

M0 

M1 

CD8 

CD7 

No visceral 

organ 

involvement 

visceral organ 

involved 

B0 a Sezary 

cells 5%, 

clonal 

B2 

Sezary 

cells 

>1000/µl 

Clonal 

Folliculotropic 

MF 

Mucinous 

degeneration of 

hair follicles 

(follicular 

mucinosis) 

Epidermis is 

spared 

Plaques over 

the head. 

Alopecia+ 

Atypical CD4+ T- 

cells 

Pagetoid MF 

Epidermotropism 

+++ 

Localized type: 

Woringer Kolopp 

Disseminated 

type: Ketron 

Goodman 

Hyperplastic 

epidermis 

infiltrated by 

lymphocytes 

CD8+ T cells 

Granulomatous 

Slack Skin 

Bulky, 

pendulous skin 

folds, flexural 

Dermis and 

subcutaneous 

tissue show 

granulomatous 

infiltrate, CD4+ 

cells, 

macrophages, 

giant cells and 

loss of elastic 

fibers 

Shows indolent 

course 

GENETICS 

● TR gene: clonal rearrangements 


● Mutations in TCR and IL2 pathways 

● Mutations in genes for TH2 cell differentiation 

● TNFSRF mediated apoptosis 

● Constitutive activation of STAT 

● Inactivation of CDKN2A (p16 INK4a) 

● Inactivation of PTEN 

PROGNOSIS 


● Adverse prognosis is indicated by 

‣ Large Pautrier’s microabscess 

‣ Atypical lymphocytes 

‣ Extracutaneous dissemination 

‣ Failure to achieve complete remission 

after initial therapy 

‣ Elderly 

‣ Raised LDH 

‣ Histological transformation 


Chapter 6.11: Sezary Syndrome 


INTRODUCTION (Table 1) 

Table 1: Diagnostic Criteria for Sezary Syndrome 

Triad of 

• Erythroderma 

• Generalized lymphadenopathy 

• Presence of clonally related neoplastic T-cells with 

cerebriform nuclei in skin/LN/peripheral blood 

And one of the three: 

• Absolute Sezary cell count ≥ 1000/μL 

• CD4:CD8 ≥ 10 

• Loss of T-cell antigens 

Demographics: Elderly males 


● A generalized disease which involves 

oropharynx, lungs, skin, CNS 

● BM involvement is variable 


● Generalized skin lesions: pruritus, alopecia, 

ectropion, palmar and plantar hyperkeratosis, 

onychodystrophy 


● Skin: Monotonous cellular infiltrates with 

Sezary cells. Epidermotropism noted (may be 

absent) 

● LN: Effacement of LN architecture 

● PB: Sezary cells (atypical lymphoid cells with 

cerebriform nuclei) 

● BM may be involved 

Figure 2 

Picture credits: Michael Cascio, MD (@mjcascio) 


● Positive: CD3, CD4, CD279 (PDL1), CCR4, CCR7, 

CLA (common leukocyte antigen) 

● Negative: CD7, CD8, CD26 

GENETICS 

● TCR gene clonal rearrangements 

● Genes: overexpression of PLS3, DNM3, TWIST1, 

EPHA4 

● Under expression of STAT4 

● Del CDKN2A 

● Loss of function ARID1A 

● Gain of function PLCG1, CD28, TNFRSF1B 

● Activation of NFκB, STAT3, JAK-STAT 

● Loss of chr 1p, 6q, 10q 

● Gain of chr 8q 

● Iso 17q 

● Inactivating mutation in p53 

● Hypermethylation and activation of FASdependent 

apoptotic pathway 

PROGNOSIS 

● Aggressive disease 

● LN involvement and extracutaneous 

involvement: worse prognosis 

STAGING 

● Staging is that of ISCL/ EORTC for mycosis 

fungoides. Thus, Sezary syndrome cases are 

usually IVA1, IVA2 or IVB 

Mycosis Fungoides 

Evolving skin lesions 

Sezary Syndrome 

Generalized skin involvement 

LN involved in advanced 

stages 

Could be in any stage 

Excellent prognosis 

Generalized 

Lymphadenopathy is an 

essential feature 

Stage IVA1/IVA2/IVB 

Poor survival 


Chapter 6.12: Hepatosplenic T-cell Lymphoma (HSTCL) 


INTRODUCTION 

● Aggressive disease with poor outcome 

● phenotype 

● Involves: liver, spleen, bone marrow 

Demographics 

● Rare lymphoma 

● Males from adolescence to young age 


● Patients have a history of immunosuppression, 

e.g., organ transplant, treatment for Crohn’s, 

Psoriasis, Rheumatoid arthritis 

● Marked splenomegaly, hepatomegaly 

● No evidence of lymphadenopathy 

● Bone marrow is always involved, therefore Ann 

Arbor stage IV always 

● Thrombocytopenia with anemia, leukopenia 

● CD3 is positive 

● CD56 +/- 

● CD4, CD8, CD5 are not expressed 

● Cytotoxic granule markers: Granzyme M, TIA1 

are expressed, but not Granzyme B and Perforin 


Macroscopy: Spleen and liver are enlarged 

Microscopy 

● Uniform population of medium-sized cells with 

the rim of cytoplasm. Chromatin is loosely 

condensed with small inconspicuous nucleoli 

Spleen: 

● White pulp: atrophic 

● Red pulp: congested with tumor cells 

Liver: Sinusoids are infiltrated by tumor cells (Fig 1) 

Bone Marrow: Tumor cells present intra-sinusoidally 


● phenotype 

Figure 1 

GENETICS 

● TRG, TRD genes are rearranged 

● Isochromosome 7q. It encodes for ABCB1 

● Trisomy 8 

● A missense mutation at STAT5B, STAT3 

● Mutations in SETD2, INO80, ARID1B (these are 

chromatin-modifying genes) 


● Very aggressive course 

● Short median survival 

● Platinum-cytarabine and pentostatin are tried 

for better outcome 


Chapter 6.13: Primary cutaneous CD30-positive T-cell 



INTRODUCTION 

● Second most common group of cutaneous TCLs 

Lymphomatoid 

papulosis 

PC-LPD 

Borderline 

LYMPHOMATOID PAPULOSIS (LYP) 

● Chronic, recurrent, self-healing 

Demographics: Adult, males 

Site of involvement: 

● Confined to the skin of trunks and extremities 


● Papulonecrotic skin lesions appear and 

disappear within 3 – 12 weeks. They leave 

behind superficial scars 

MORPHOLOGY AND PHENOTYPE (SEE TABLE 1) 

Courtesy: Benjamin Wood, MD (@BenjaminAWood) 

Primary 

cutaneous ALCL 

Figure 1 

Figure 2 

GENETICS 

● Clonally rearranged TR genes 

● Rearrangement of DUSP22-IRF4 on 

chromosome 6p25.3 in a subset of cases 

PROGNOSIS 


● Risk of developing systemic lymphoma thus 

needs a long-term follow-up 

PRIMARY CUTANEOUS ALCL 

INTRODUCTION 

● Composed of CD30+ large cells having anaplastic 

morphology 

Demographics: Adult males 


● Limited to the skin of trunk, face, hands, and 

legs 


● Skin nodules are noted, usually solitary 

● Ulcerations noted in few lesions 

● 10% may show extracutaneous dissemination 


Microscopy 

● Confluent sheets of tumor cells are seen in the 

dermis. Epidermotropism noted in some cases 

● Tumor cells are: 

‣ Large, markedly pleomorphic 

‣ Irregular round to oval nucleus 

‣ Prominent eosinophilic nucleoli 

‣ Abundant cytoplasm 

● Reactive inflammatory cells present 


● Mainly CD4+ 

● Express cytotoxic granule proteins: TIA1, 

granzyme B, perforin 

● CD30 expressed 

● CLA (common lymphocyte antigen)+ 

● CD15, IRF4/MUM1 + in few cases 

● Variable loss of CD2/CD5/CD3 

● EMA, ALK, PAX5, EBV are not expressed 


GENETICS 

● Clonal rearrangements in the TCR gene 

● Rarely, t(2;5) is noted (ALK-positive). Such cases 

have an excellent prognosis 

● Some have DUSP22-IRF4 rearrangements 

● A gain of 7q31, loss of 6q16-21 and 13q34 

● NPM1-TYK2 gene fusion causes STAT signaling 

activation. This has an aggressive clinical course 

● Gene expression profiling: CCR10, CCR8 is 

expressed; thus, explains its affinity for the skin 

PROGNOSIS 

● Favorable 

Table 1: Histologic subtypes of Lymphomatoid Papulosis 

Type A Type B Type C Type D Type E LyP with 6p25.3 


Other rare 

variants 

Most common 

Reactive 

inflammatory 

background 

and atypical 

cells scattered 

amidst it 

Atypical cells 

exhibiting 

epidermotropism 

Inflammatory 

cells are rarely 

seen 

Sheets 

of large 

atypical 

cells 

Atypical cells are 

small to mediumsized 


and Pagetoid 

spread 

Angiocentricity 

and 

angiodestruction 

Causes vascular 

obstruction 

Extensive 

necrosis and 

ulcerations 

Eschar-like 

lesions 

Localized skin 

lesions 


by small cells 

Dermis shows 

large blasts 

DUSP22-IRF4 

gene fusion 

Folliculotropic 

Syringotropic 

Granulomatous 

CD30+ CD30+/- CD30+ CD30+ CD30+ Blasts in the 

dermis are 

CD30+, small 

atypical cells in 

the epidermis are 

weak CD30 

CD4+ 

CD8 Neg 

CD4+ 

CD8 Neg 

CD4+ 

CD8 Neg 

CD4 Neg 

CD8+ 

CD4 Neg 

CD8+ 

CD4 Neg 

CD8+ 


Chapter 6.14: Primary cutaneous peripheral T-cell 

lymphomas, rare subtypes 


Table 1: Primary cutaneous peripheral T-cell lymphomas, rare subtypes 

PC gamma-delta 

TCL 

PC aggressive 

epidermotropic 

CD8+ cytotoxic TCL 

PC CD4+ 

small/medium 

TCL 

PC acral CD8+ TCL 

Demographics 

In adults with an 

impaired 

immune system 

Adult males 

Clinical 

presentation 

Patch/ plaque/ 

nodules seen on 

skin on the 

extremities 

Generalized skin 

lesions with 

ulceration and 

necrosis 

Solitary skin lesion 

on the scalp as 

raised 

erythematous 

nodule 

Ears (helix, concha) 

> nose, foot, 

eyelids. 

Tiny reddish slowgrowing 

nodule 

Morphology 

Epidermal or 

dermal or 

subcutaneous 

infiltration of 

neoplastic cells. 

Pagetoid spread 

+ 

Cells: large, with 

coarse 

chromatin. 

Exhibit apoptosis 

and necrosis. 

Angioinvasion+ 

Epidermis: 

ulceration + 

acanthosis + 

atrophy 

Blister formation+ 

Angiocentricity+ 

Angioinvasion+ 

The dermis is 

densely infiltrated 

by small to 

medium atypical 

cells with reactive 


around them 

Dermal infiltration 

by a monotonous 

population of 

atypical cells. 

Medium-sized with 

an irregular 

nucleus and small 

nucleoli. 

Reactive 

lymphocytes seen 

around 

Positive markers 

CD3, CD2, CD56, 

gamma-delta 

phenotype 

Cytotoxic granule 

markers + 

CD3, CD8, CD45RA, 

BF1 phenotype 

Cytotoxic granule 

markers + 

CD3, CD4, PD1, 

BCL6, CXCL13. 

Low Ki67 

CD3, CD8, TIA1, 

and CD68 (Golgilike 

staining), low 

Ki67, BF1 

phenotype 

Negative markers 

CD5, BF1 

phenotype, CD4, 

CD8 

CD4, CD45RO, CD5, 

CD2, CD30 

CD10, CD30, CD8 

CD2, CD5, CD7, 

CD4, granzyme B, 

perforin, NK-cell 

markers, TFH 

markers 

Genetics 

Clonal rearrangements in the TCR gene 

Prognosis 

Poor, median 

survival is 15 

months 

Poor, median 

survival is 12 

months 

Excellent 

Needs surgery + 

intralesional 

steroid +/- 

radiotherapy 

Good, 

Requires only 

surgical excision. 

Avoid 

overtreatment. 


Chapter 6.15: Peripheral T-cell lymphoma, NOS (PTCL) 


INTRODUCTION 

● Nodal and Extranodal T-cell Lymphoma (TCL) 

● Aggressive clinical course 

Demographics: Adult males are involved 


● Lymph nodes are involved 

● In advanced stage marrow, liver, spleen, 

peripheral blood are also involved 



● Also presents with paraneoplastic features like 

eosinophilia, pruritus, hemophagocytic 

syndrome 


Lymph Node 

● Effacement of architecture 

● Diffuse and paracortical infiltrates 

● Tumor cells are medium to large-sized, with an 

irregular, pleomorphic, hyperchromatic 

(sometimes vesicular) nucleus and prominent 

nucleoli 

● Rarely mitotic figures, clear cells, and RS-like 

cells are seen 

● Background of inflammatory cells 

● Lymphoepithelioid variant: evidence of 

epithelioid histiocytes 

Skin 

● Atypical cells infiltrate the dermis and 

subcutaneous tissue 

● Nodules over the skin may ulcerate 

Spleen 

● Multiple nodules noted with diffuse 

involvement of white pulp 

Variant: 

● Lennert lymphoma (lymphoepithelioid variant) 

(Fig 1, 2) 

‣ Diffuse or interfollicular growth 

‣ Small cells with nuclear irregularities 

‣ CD8 positive 

‣ Epithelioid histiocytes and admixed 


‣ Better prognosis 


● Aberrant T-cell phenotype 

● CD5 and CD7 are downregulated 

● CD4 positive/CD8 negative in nodal cases 

● CD4 /CD8 dual positive or dual negative seen in 

some cases 

● CD8, CD56 expressed in some cases 

● Cytotoxic granular markers TIA 1, granzyme B, 

perforin can be expressed 

● CD15 positivity is suggestive of adverse 

prognosis 

● Few cases express CD25 and are a target for 

immunotoxins 

● Aberrant expression CD20, CD79a 

● Ki67 is high if > 70%: worse prognosis 

● Gene expression profiling: TBX21(TBET) and 

GATA3 

Figure 2 

CD4 

Figure 1 

CD8 


GENETICS 



● Deregulation of a variety of genes, e.g., PDGFRA 

PROGNOSIS 

● Highly aggressive lymphoma 

● Has poor response to therapy 

● Factors associated with poor prognosis: 

‣ BM involvement 

‣ Ki67 >70 % 

‣ EBV positivity 

‣ NFkB pathway regulation 

‣ High proliferation signature 

‣ >70% of cells are transformed lymphoblasts 

‣ GATA3 expression 

‣ CD30 positivity 


INTRODUCTION TO TFH CELLS 

Chapter 6.16: Angioimmunoblastic T-cell lymphoma and 

other nodal lymphomas of T follicular helper (TFH) cell 

origin 


Figure 1 

TFH cell 

markers 

CD10 

CD200 

CXCL3 

CXCR 

BCL6 

SAP, MAP 

ANGIOIMMUNOBLASTIC T-CELL LYMPHOMA 

INTRODUCTION 

● Aggressive neoplasm of mature CD4+ TFH-cells 

● Lymph node involvement 

● Proliferation of high endothelial venules (HEVs) 

and FDCs 

● EBV associated but tumor cells are EBV negative 

Demographics 

● Middle-aged to elderly 

● Males > females 

Site of localization 

● Lymph nodes, spleen, liver, skin, BM 




● Hypergammaglobulinemia 

● Skin rash, pruritus 

● Pleural effusion, ascites 

● Arthritis 

● Lab diagnosis: circulating immune complexes, 

cold agglutinins, rheumatoid factor+, anti-SMA+ 


Lymph Node 

● Partial or complete nodal involvement with 

perinodal infiltration 

● Cortical sinuses: spared 

● HEVs are prominent 

● Neoplastic cells cluster around HEV 

‣ Small to medium-sized 

‣ Clear to pale cytoplasm 

‣ Distinct cell membrane 

‣ Cytological atypia 

● Polymorphous inflammatory background: 

Reactive lymphocytes, histiocytes, plasma cells, 

eosinophils 

● Associated FDCs form a meshwork. Clusters of 

neoplastic cells surrounded by the dendritic 

process of FDCs which are CD21+ 

● Tumor rich AITL (advanced phase): has reduced 

inflammatory cells and more tumor cells (large 

cells and clear cells) 

● Paracortical immunoblasts are EBV infected 

● Polyclonal plasma cell proliferation 


Table 1: Histologic patterns of AITL 

Pattern 1 Pattern 2 Pattern 3 

Figure 4 

• Neoplastic cells 

surround 

hyperplastic 

follicles 

• Mimics reactive 

lymphoid 

hyperplasia 

• No mantle zone 

• Regression of 

follicles 

• Paracortical 

expansion filled 

by neoplastic 

cells 

• Effacement of 

nodal 

architecture 

• LN is replaced 

by neoplastic 

cells 

Figure 2 

Figure 3 

Figure 5 


Phenotype 

T-cell markers 

TFH phenotype 

FDC meshwork 

Background B-cells 

Markers 

CD2, CD3, CD4, CD5 

CD10, CXCL13, ICOS, BCL6, 

PD1 

CD21, CD23, CD35 

EBV positive 

CD3 

PD1 


GENETICS 

● Clonal TR gene, IG gene rearrangement 

● EBV infected B-cells with destructive 

hypermutations in IG gene are known as 

forbidden B-cells. These cells are 

immunoglobulin deficient 

● Gene expression profiling: overexpression of B- 

cell-related genes, FDC genes, chemokines, 

extracellular matrix related genes 

● Cytogenetics: 

‣ Trisomy 3, 5, 21 

‣ Gain of chr X and loss of 6q 

● Mutations in genes responsible for epigenetic 

modifications: IDHs, TET2, DNMT3A, RHOA 

● Mutations in genes responsible for T-cell 

signaling: FYN, PLGC1, CD28 (CTLA4-CD28 

fusion) 

● Rarely t(5;9)(q33;q22) ITK-JYK 

PROGNOSIS 


● Male gender, mediastinal LN involvement, and 

anemia associated with poorer prognosis 

FOLLICULAR T-CELL LYMPHOMA 

INTRODUCTION 

● Nodal neoplasm of TFH-cells 

● No evidence of HEV 

● Neoplasm of TFH cells with a nodular/ follicular 

growth pattern and lack features characteristic 

of AITL (no evidence of HEVs, no evidence of 

FDCs outside the follicles) 

Demographics 

● Rare 

● Elderly males 

Site of involvement and Clinical Symptoms 



● B-symptoms 

● Skin rash 

● Hypergammaglobulinemia may or may not be 

present 

● Eosinophilia may or may not be present 


Lymph Node 

● Partially/ completely effaced LN architecture 

● Follicular lymphoma-like pattern: well-defined 

nodules of tumor cells 

● Progressive Transformation of Germinal 

Center-like pattern: irregular nodules composed 

of tumor cell aggregates and surrounded by 

IgD+ mantle zone B-cells 

● Tumor cells are intermediate-sized, with 

abundant cytoplasm and a round nucleus 

● Polymorphous background and prominent HEVs 

as seen in AITL are not present 

● Occasionally immunoblasts and RS-like cells are 

seen 


Phenotype 

Markers 

T-cell markers 

CD2, CD3, CD4, CD5 

CD7 is negative 

T FH phenotype 

CD10, CXCL13, ICOS, BCL6, PD1 

FDC meshwork 

CD21, CD23, CD35 

Occasional immunoblasts CD20, EBV+ (subset of cases) 

Occasional RS-cells CD30, CD15, 

weak PAX5 

GENETICS 

● Clonal TR gene rearrangements 

● t(5;9)(q33; q22) ITK-SYK fusion is specific for 

FTCL 

● Mutations in TET2, RHOA, DNMT3A 

PROGNOSIS 


NODAL PERIPHERAL T-CELL LYMPHOMA WITH TFH - 

PHENOTYPE 

● At least 2 (ideally 3) TFH markers and CD4+ 

● No prominent inflammatory cells 

● No vascular proliferation / HEV 

● No FDCs around the follicles 

● LN is diffusely infiltrated by TFH-phenotype 



Clinical 

Table: TFH Phenotype Lymphomas at a glance (Credits: Dr. Laura Brown) 

Angioimmunoblastic T-cell 

Lymphoma 

Follicular T-cell Lymphoma Nodal PTCL with TFH phenotype 

Elderly male 

Elderly male 

Variable 

Generalized 

Generalized 

LN enlargement 

Lymphadenopathy 

Lymphadenopathy 

Hepatosplenomegaly Splenomegaly 

Hypergammaglobulinemia B-symptoms 

Skin rash, pruritus 

Skin rash 

Hypergammaglobulinemia 

Pleural Effusion 

Eosinophilia +/- 

Arthritis 

Ascites 

LN architecture Pattern 1 - 3 FL-like or PTGC-like Diffuse involvement 

Cytology Small to medium sized tumor Only neoplastic cells. Only neoplastic cells. 

cells + HEV + FDCs 

No evidence of HEV / FDCs No evidence of HEV/FDCs 

Background Polymorphous: inflammatory No such background No such background 

cells and FDC meshwork 

Vascularity Prominent, HEV +++ None None 

Neoplastic cells T-cell markers + TFH markers T-cell markers + TFH CD4+ at least 2 TFH markers 

markers 

B-bells EBV positive EBV positive None 

Genetics Clonal TCR and IGH 

t(5;9)(q33;q22) ITK-SYK Mutations in TET2, DNMT3A, 

rearrangements and others fusion is specific for FTCL RHOA 

Prognosis Poor 

Poor 

Variable 

Median survival

Chapter 6.17: Anaplastic large cell lymphoma, ALK-positive 

INTRODUCTION 

● T-cell lymphoma consisting of large lymphoid 

cells with abundant cytoplasm and pleomorphic, 

often horseshoe-shaped nuclei 

● Show a chromosomal translocation involving the 

ALK gene and expression of ALK protein and 

CD30 

Demographics 

● Common in the first three decades of life 



● Lymph nodes and extranodal sites 

● Commonly involved extranodal sites: skin, bone, 

soft tissue, lungs, and liver 

● Bone marrow involvement is subtle and best 

seen on IHC 

● Small cell variant of ALK+ ALCL may have a 

leukemic presentation 


● Present with advanced (stage III-IV) disease with 

peripheral and/or abdominal lymphadenopathy, 

often associated with extranodal infiltrates and 

involvement of the bone marrow 

● B symptoms especially high fever 


Lymph Node 

● Hallmark cells: Neoplastic cells with eccentric, 

horseshoe-shaped nuclei with the eosinophilic 

region near the nucleus 

● These cells are seen in all morphological variants 

● Doughnut cells: Neoplastic cells containing 

pseudoinclusions due to plane of sectioning 

● Patterns of growth: 

● Common pattern: Clear, basophilic, or 

eosinophilic abundant cytoplasm, cells 

resembling RS cells may be seen, cells grow in 

sinuses and may resemble metastatic tumor 

● Small cell pattern: Small to medium-sized cells 

with irregular nuclei, fried egg appearance may 

be seen, hallmark cells always present, 

concentrated around blood vessels, 

misdiagnosed as Peripheral T-cell lymphoma 

Nupur Sharma Vanya Jaitly Akanksha Gupta 

● Lymphohistiocytic pattern: Tumor cells admixed 

with reactive histiocytes, cells smaller than the 

common pattern, cluster around blood vessels, 

and highlighted using CD30 or ALK 

● Hodgkin-like pattern: Features similar to 

nodular sclerosis Hodgkin Lymphoma 

● Composite pattern: More than one pattern 

present 

Figure 1 

Picture credits: Katelyn Dannheim (@KateDannheimMD) 

Differential Diagnosis 

● DLBCL with immunoblastic/plasmablastic 

features (ALK-positive): Absent CD30, 

characteristic cytoplasm-restricted granular 

staining for ALK protein 

● ALK-positive histiocytosis: occurs in early 

infancy, the proliferation of histiocytes, CD30 

negative, CD68 positive 


● Positive: CD30 on the cell membrane and Golgi 

region, 

‣ ALK (in large cells is both cytoplasmic and 

nuclear, ALK in small cell variant is restricted 

to the nucleus) 

‣ EMA: Most cases are positive 

‣ CD2, CD5, CD4 and CD25 

‣ TIA1, Granzyme and Perforin 

● Negative: CD3, CD68, BCL2, EBV 

● In cases with variant translocations, i.e., fusion 

of ALK to partners other than NPM1, the ALK 

staining is usually cytoplasmic 


Figure 3 

Figure 2 

EMA 

CD2 

CD30 

ALK-1 

CD43 

MIB-1 

GENETICS 

● Most common t(2;5) between ALK on 

chromosome 2 and NPM1 on chromosome 5 

● Others include t(1;2) and inv(2) 


● Poor prognostic factors: 

● MYC rearrangement 

● Small cell or lymphohistiocytic variant 

● Relapses remain sensitive to chemotherapy 


Chapter 6.18: Anaplastic large cell lymphoma, ALK-Negative 


INTRODUCTION 

● CD30 positive T-cell lymphoma with morphology 

similar to ALK-positive ALCL, but lacking 

expression of ALK protein 

Demographics 

● Most common in older adults (unlike ALKpositive 

ALCL which is seen in children and 

young adults) 


● Nodal and extranodal disease is seen 

● Extranodal sites commonly involved: skin, bone, 

soft tissue, lungs, and liver (less commonly 

involved than ALK-positive ALCL) 

● Systemic ALK+ ALCL with cutaneous involvement 

should be differentiated from primary 

cutaneous ALCL 

● Gastrointestinal tract involvement should be 

differentiated from CD30 positive enteropathy 

associated lymphomas 


● Stage III-IV disease with peripheral and/or 

abdominal lymphadenopathy 

● B symptoms 


● Solid, cohesive sheets of neoplastic cells replace 

nodal or tissue architecture 

● When lymph node architecture is preserved, the 

neoplastic cells typically grow within sinuses or 

within T-cell areas, commonly showing a socalled 

cohesive pattern, which may mimic 

carcinoma 

● Hallmark cells: Neoplastic cells with eccentric, 

horseshoe-shaped nuclei with the eosinophilic 

region near the nucleus 

● Multinucleated cells, including wreath-like cells, 

may also be present 

● Doughnut cells: Neoplastic cells containing 

pseudoinclusions due to plane of sectioning of 

nuclear invagination, more common in cases 

with DUSP22-IRF4 rearrangement 

Figure 1 

Figure 2 


● Positive: strong and diffuse CD30 on all cells 

(cell membrane and Golgi region) 

● Important to differentiate from PTCLs which 

express CD30 in at least a proportion of the 

cells, and usually with variable intensity 

● CD2, CD3, CD43 and CD4 positive 

● TIA1, granzyme and perforin positive (absent in 

cases with DUSP22) 

● Some cases are EMA positive 

● Clusterin positive 

● Negative: PAX5 (weak expression seen in CHL), 

EBV 


Figure 3 

Figure 4 

CD30 

CD3 

Table 1: Differential diagnosis of ALCL, ALK Negative 

IHC 

MARKERS 

ALK NEG 

ALCL 

PTCL, 

NOS 

CHL 

CD30 + +/- + 

PAX5 - - DIM + 

CD2, CD3, + + - 

CD5 

EBER AND - - + 

EBV LMP-1 

CD15 - +/- + 

CYTOTOXIC + +/- - 

CELL 

MARKERS 

CLUSTERIN + - - 

T-CELL 

- + - 

RECEPTOR 

PROTEIN 

ALCL-Anaplastic Large Cell Lymphoma, ALK- anaplastic 

lymphoma kinase, EBV- Epstein Barr virus, EBER- EBV 

encoded RNA, LMP-1 - Latent membrane protein 1, 

+ denotes positive, - denotes negative 

GENETICS 

● JAK/STAT3 tyrosine kinase activation 

● DUSP22 rearrangement 

● TP63 rearrangement 

● Gains of 1q, 6p, Sq, and 12q and losses of 4q, 

6q21 

● Expression of TNFRSFB, BATF, and TM001 genes 

(absent in PTCL, NOS) 


● Worse outcome than ALK-positive ALCL 

● TP63 rearrangement and loss of PRDM1 

associated with poor outcome 

DIFFERENTIAL DIAGNOSIS (REFER TABLE 1) 

● Primary cutaneous ALCL (C-ALCL), other 

subtypes of CD30+ T-cell or B-cell lymphoma 

with anaplastic features, CHL 


Chapter 7: Breast Implant Associated ALCL 

Nupur Sharma 


INTRODUCTION 

● T-cell lymphoma arising in association with breast 

implants 

● Morphological features resemble ALCL, ALKnegative 

Demographics 



● Seroma cavity or pericapsular fibrous tissue, 

sometimes forming a mass 

● Local and regional lymph nodes may be involved 


● Stage I disease, usually with a peri-implant 

effusion and less frequently, a mass 


● Large and pleomorphic tumor cells 

● Hallmark cells seen in other forms of ALCL can 

also be identified 

Figure 1 

Figure 3 


● Positive: CD30 (strong and uniform expression) 

● Negative: ALK 

● Incomplete expression of pan-T-cell antigens 

Figure 4 

CD30 

Figure 2 

GENETICS 



● Recurrent activating JAK1 and STAT3 mutations 


Prognosis 

● Excellent 

● Most important adverse prognostic factor is the 

presence of a solid mass of tumor cells, which 

may indicate a need for systemic therapy 


Chapter 7.0: Hodgkin Lymphoma 

S. Kannan Akanksha Gupta 

Chapter 7: Hodgkin 

Lymphoma 






INTRODUCTION 

● Lymphoid neoplasms with large dysplastic 

mononuclear and multinucleated cells 

surrounded by a variable mixture of mature nonneoplastic 


● Inflammatory background of non-neoplastic 

cells is due to abnormal expression of cytokines 

and chemokines 

● Ring of T-cells (Th2) in a rosette-like manner 

around large cells 

Two major types: 

● NLPHL with preserved B-cell program 

● CHL with downregulated B-cell program 

● Histological subtypes of CHL 

‣ Nodular sclerosis CHL (NSCHL) 

‣ Mixed cellularity CHL (MCCHL) 

‣ Lymphocyte-rich CHL (LRCHL) 

‣ Lymphocyte-depleted CHL (LDCHL) 

Demographics 

● NLPHL: Middle ages to elderly, M>F 

● MCCHL: Bimodal with a peak in young patients 

& 2 nd peak in older adults 

● NSCHL: Peak at adolescence to middle age 


● CHL: Cervical lymph nodes (most common) > 

mediastinal>axillary > para-aortic regions 

‣ Mediastinal involvement common (mostly 

NSCHL) 

‣ Abdominal involvement and splenic 

involvement (MCCHL) 

‣ Bone marrow rarely involved 

‣ NLPHL: Peripheral lymph nodes, spares axial 

lymph nodes 


● CHL: Peripheral lymphadenopathy, localized 

to one or two lymph node-bearing areas with B 

symptoms: fever, drenching night sweats, and 

significant bodyweight loss 

● NLPHL: B symptoms rare 


Lymph Node 


● Grossly, enlarged, and encapsulated lymph node 

with “fish-flesh” cut section 

● NSCHL: Nodularity, dense fibrotic bands, and a 

thickened capsule 

● Effaced architecture due to variable numbers of 

Hodgkin/Reed–Sternberg (HRS) cells admixed 

with a rich inflammatory background 

● Neoplastic cells are a minority 

● Reactive cellular infiltrate varies according to the 

histological subtype 

Classic Reed-Sternberg cell (Figure 1, 2) 

● Prototypical RS cell: Two separate nuclear lobes: 

so-called owl’s eye appearance have abundant 

slightly basophilic cytoplasm 

● Nuclei are large and rounded in contour, with a 

prominent, irregular nuclear membrane, pale 

chromatin and usually one prominent eosinophilic 

nucleolus 

● Perinuclear clearing (a halo), resembling a viral 

inclusion 

Figure 1 

Figure 2 


Variants of RS cell 

● Mononuclear variants 

● Mummified cells with condensed cytoplasm and 

pyknotic reddish nuclei 

● Lacunar Reed–Sternberg in NSCHL 

NLPHL 

● LP cells (lymphocyte predominant): Lobed nuclei, 

with smaller basophilic nucleoli with a rim of pale 

cytoplasm 

● Background predominance of lymphocytes 

● Epithelioid histiocytes around the nodules, 

sometimes in clusters 

Bone Marrow and Liver 

● Identification of atypical mononuclear (CD30+ 

Hodgkin cells ± CD15) in the appropriate 

inflammatory background 

● Diagnostic multinuclear RS cells are not required 

in a diagnosed patient of CHL 

Spleen 

White pulp 

● Scattered nodules within the white pulp; 

rarely very large masses 

● Fibrous bands in the nodular sclerosis subtype 

Thymus 

● Cystic degeneration and epithelial hyperplasia 


CHL 

● Crippled B-cell program 

● Positive for CD30 (nearly all cases) & CD15 

in most cases and show membranous pattern 

with accentuation in the Golgi area of the 

cytoplasm. In a minority of the neoplastic cells, 

CD15 may be restricted to the Golgi region 

● Positive for PAX5 (weaker than that of 

reactive B-cells), IRF4/MUM1 & PRDM1 (BLIMP1) 

in a few cases 

● CD20 shows weak and varied intensity in a 

minority of the neoplastic cells 

● EMA is rare and weak 

● OCT2/BOB1 negative, PU1 negative 

● CD79a & CD138 negative 

● CD45 & PGM1 epitope of CD68 negative 

● Type II EBV latency: LMP1 and EBNA1 without 

EBNA2 

● T-cell antigens are negative; rarely aberrant or 

artifactual membranous expression 

● 

No immunoglobulin expression as B-cell program is 

downregulated 

NLPHL 

● Preservation of the B-cell program 

● Positive for CD20, CD45, CD79a, PAX5, OCT2, 

and BOB1 

● EMA is sometimes positive, but often only in a 

fraction of the LP cells 

● IgD positive (but not IgM) in a subset of young 

males 

● Ig light chains negative 

● Negative for CD15 and CD30 may be weakly 

expressed in some cases 

GENETICS 


● HLA class associations and single nucleotide 

polymorphism (SNP) linked to CHL 

Abnormal gene expression 

● HRS cell with B-cell–inappropriate gene products: 

‣ NF-kappaB is constitutively activated 

‣ JAK/STAT signaling pathway: Mutations of 

the JAK regulator SOCS1 with nuclear STAT5 

accumulation in HRS 

● Overexpression of p53, PDL1, and PDL2 

Antigen receptor genes 

CHL 

● Clonal Ig gene rearrangement with a high load of 

somatic mutations without signs of ongoing 

mutations 

● Downregulated B-cell program due to 

hypermethylation of multiple genes and pathways 

● HRS cells do not express Ig transcripts 


● Nonsense mutations in the V region genes 

NLPHL 

● Clonal Ig gene rearrangement with a high load 

of somatic mutations and signs of ongoing 

mutations in the variable (V) region 

● Functional Ig mRNA transcripts are detectable 

in the LP cells with OCT2/BOB1 expression 

Cytogenetics 

● Conventional cytogenetic and FISH: Aneuploidy 

and hypertetraploidy, consistent with the 

multinucleation 

● t(14;18) and t(2;5) are absent but t(14;18) may 

occur in CHL arising in FL 

● CGH reveals recurrent gains and amplifications 


Prognosis 

CHL 

● CHL curable in most cases with current therapy 

● Interim FDG-PET distinguishes between good-risk 

patients and poor-risk patients requiring more 

intensive treatment 

● Risk groups: Early, intermediate, and advanced 

stages based on: 

‣ The extent of disease (according to the Ann 

Arbor system) 

‣ Clinical risk factors: 

‣ Large mediastinal (bulky) mass 

‣ Extranodal disease 

‣ ↑ESR 

‣ 3 or 4 nodal areas 

● In advanced stages, International Prognostic 

Score (IPS), consisting of 7 risk factors, 

correlates with prognosis 

● Tumor-infiltrating macrophages (CD68 

positive) associated with an adverse prognosis 

and is seen in aggressive forms of CHL, and 

lymphocyte-depleted (LDCHL) 

Treatment 

● ABVD (i.e., doxorubicin, bleomycin, vinblastine, 

and dacarbazine) 

● BEACOPP (bleomycin, etoposide, doxorubicin, 

cyclophosphamide, vincristine, procarbazine, and 

prednisone) 

● Radiotherapy 

Novel targeted treatment 

● Anti-CD30 antibody-drug conjugate brentuximab 

vedotin for relapsed/refractory CHL 

● Anti-PD1 antibodies 

NODULAR LYMPHOCYTE PREDOMINANT HODGKIN 

LYMPHOMA 

INTRODUCTION 

● B-cell neoplasm with a nodular or a nodular 

and diffuse proliferation of small lymphocytes 

with single scattered large neoplastic cells: 

Lymphocyte predominant (LP) or popcorn cells 

(formerly L&H cells: lymphocytic and/or 

histiocytic Reed–Sternberg cell variants) 

Demographics 

● Males, middle age 


● Cervical, axillary, or inguinal lymph nodes, rarely 

mediastinal 

● Mesenteric lymph nodes 

● Spleen and bone marrow 

● Destructive bone lesions (rare) 


● Localized peripheral lymphadenopathy (stage I/II) 

● Advanced-stage disease in some cases 


Lymph Node 

● Architecture effaced, totally or partially 

● Replaced by a nodular, nodular and diffuse, or 

predominantly diffuse infiltrate consisting of small 

lymphocytes, histiocytes, epithelioid histiocytes, 

and intermingled LP cells 


● Immunoarchitectural growth patterns: 

● LP cells 

‣ Large cells with a single large nucleus and 

scant cytoplasm 

‣ Nuclei folded or multilobed (hence popcorn 

cells) 

‣ Nucleoli multiple, basophilic & smaller than 

those of classic RS cells. (Rarely ≥1 prominent 

nucleolus resembling classic RS cell) 

● Histiocytes and polyclonal plasma cells can be 

found at the margin of the nodules with LP cells 

● Neutrophils and eosinophils are uncommon 

● Reactive follicular hyperplasia ± PTGC 

(progressive transformation of germinal centers) 

can be seen 

● Sclerosis: primary biopsies & recurrences 

● Residual small germinal centers are rarely 

present in the nodules of NLPHL 

Figure 3 

● Patterns A, B, C, and F have variably large 

spherical meshwork of follicular dendritic cells 

(FDC) 

● THRLBCL overlap prominence of extranodular LP 

cells is associated with a diffuse pattern & loss of 

FDC meshwork which resembles THRLBCL 

Figure 4 



LP cells 

● Positive: CD20, OCT2, CD79a, BOB1, PAX5, 

CD45, BCL6, EMA, CD75 

o IgD-positive, especially young males 

o Staining for light and/or heavy chains is 

variable 

o Ki67 nuclear positivity in LP cells (LP cells 

are usually in cycle) 

● Negative: CD10, CD15, and CD30 (rarely weak 

positive and reactive immunoblasts are CD30 

positive) 

FDC meshwork 

● CD21 positive (patterns A, B, and C) 

● Filled with small B-cells and a varying number of 

T-cells of the T Follicular Helper (THF) type 

T-cells rosette 

● T-cells rosette around LP cells which are 

PD1/CD279 positive and/or CD57 positive: 

Belong to germinal center T-cells, and subset 

are positive for MAF, BCL6, IRF4/MUM1 and 

CD134 

● CD4+/CD8+/CD57+/PD1+ T-cells favor NLPHL 

with diffuse pattern versus dominant presence 

of CD8+, TIA1+ cells, low CD57+ T-cells, and no 

small B-cells favor primary THRLBCL 

GENETICS 

● Clonally rearranged IG (IGHV) 

● High load of somatic mutations 

● Functional and ongoing mutations with IG 

mRNA transcripts 

● BCL6 rearrangements in approximately half of 

the cases 

● Hypermutations is common in PAX5, PIM1, 

RHOH, and MYC 

● Mutations of SGK1, DUSP2, and JUNB 


● Familial preponderance 

● NLPHL is identified in Hermansky–Pudlak 

syndrome type 2 and autoimmune 

lymphoproliferative syndrome (ALPS) 


Prognosis 

● Nodular, nodular and diffuse forms develop 

slowly with frequent relapses and responsive 

to therapy 

● Stage I or II disease, very good prognosis 


‣ Variants characterized by LP cells outside 

B-cell nodules (patterns C, D, E, and F) 

‣ B-cell depletion in the microenvironment 

‣ Advanced stage 

‣ NLPHL with bone marrow involvement are 

clinically aggressive 

‣ THRLBCL-like transformation 

‣ Progression to DLBCL (rare): resemble LP cells 

or may have centroblasts or immunoblastic 

features 

NODULAR SCLEROSIS CHL 

INTRODUCTION 

● A subtype of classic Hodgkin lymphoma (CHL) 

characterized by collagen bands that surround at 

least one nodule and HRS cells with lacunar-type 

morphology 

Demographics 

● Most common CHL (Europe & USA); Common in 

resource-rich countries, M=F 

● Peak in adolescence and adults 


● Mediastinal involvement (most common) 

● Bulky disease 

● Splenic and/or lung involvement 

● Bone, bone marrow and liver involvement 



● Common presentation: Stage II disease 

● B symptoms are frequent with advanced stage 

‣ CD4, CD2, and CD3 (less common) 


Lymph Node 

Macroscopy 

● Nodular cut surface with cellular nodules 

surrounded by dense fibrosis 

● Central necrosis in grade 2 lesions 

● Post therapy: Persistent mass lesion may be 

present, with diffuse fibrotic replacement and 

no viable lymphoma (PET negativity confirms 

the absence of active disease) 

Microscopy (Figure 5, 6) 

● Nodular sclerosis 

‣ Nodular growth pattern with nodules 

surrounded by collagen bands 

‣ Broad fibroblast-poor collagen bands surround 

at least one nodule 

‣ Thickened capsule 

Lacunar cells: 

● Nuclear segmentation with smaller lobes, less 

prominent nucleoli, and a larger amount of 

cytoplasm than do HRS cells in other types 

● Cytoplasm shows cytoplasmic retraction (formalinfixation 

artifact) as if sitting in lacunae (hence the 

name) 

Syncytial variant: 

● Lacunar cells form cellular aggregates and 

cohesive nests in the centers of the nodules 

● Necrosis ± histiocytic reaction, resembling 

necrotizing granulomas 

● Background cells: Eosinophils, histiocytes, and 

neutrophils 


● CHL immunophenotype 

● Aberrant T-cell antigens by aberrant expression 

or adsorption: 

Figure 5 

Figure 6 

‣ Associated with shorter overall and eventfree 

survival 

‣ Positive PAX5 stain and IG clonality and 

negative TCR genes clonality point to CHL 

and excludes ALK-negative ALCL 

EBV association 

● EBER/EBV LMP1 expression is less frequent than 

in mixed cellularity CHL 

BNLI Grading (British National Lymphoma 

Investigation) 

NSCHL is considered Grade 2 if: 

‣ >25% of the nodules show pleomorphic cells or 

reticular lymphocyte depletion 

‣ >25% of the nodules show numerous bizarre, 

anaplastic-appearing Hodgkin cells without 

lymphocyte depletion 


‣ >80% of the nodules show features of the 

fibrohistiocytic variant 

● Necrosis should prompt grade 2 

● Grading is not mandatory for clinical purposes 

Fibro-histiocytic variant 

● May mimic a reactive process or a mesenchymal 

neoplasm 

● Fibroblasts and histiocytes are abundant 

● HRS cells may be difficult to identify without IHC 

(PAX5 and CD30 are useful; CD20 is negative) 


Prognosis 

● Better than that of other types 

● Adverse prognostic factor: Massive mediastinal 

disease 

● Grading of NSCHL may be relevant in patients with 

advanced-stage disease and has little impact on 

patients with localized disease 

MIXED CELLULARITY CHL 

INTRODUCTION 

● CHL characterized by classic Hodgkin/Reed– 

Sternberg (HRS) cells in a diffuse mixed 

inflammatory background 

● Fine interstitial fibrosis, but fibrous bands and 

capsular fibrosis are absent 

Demographics 

● Developing countries and pediatric age group 

● Frequently EBV+ and more in HIV patients 

● Second peak: Elderly individuals 



● Peripheral lymph nodes frequently involved 

● Spleen > bone marrow > liver 

● Mediastinal involvement uncommon 


● B symptoms frequent 


Lymph Node 

● Architecture effaced 

● Interfollicular growth pattern may be seen 

● Interstitial fibrosis may be present 

● No broad bands of fibrosis or capsular thickening 

(as seen in NSCHL) 

● HRS cells are typical in appearance 

● Background cells are a varying mixture of cell 

types: Eosinophils, neutrophils, histiocytes, and 

plasma cells. One of these cell types may 

predominate 

● EBV-associated cases show epithelioid histiocytes 

which may form granuloma-like clusters or 

granulomas 




Prognosis 

● With current treatment regimens, the prognosis is 

similar to other variants of CHL 

LYMPHOCYTE-DEPLETED CHL 

INTRODUCTION 

● CHL rich in HRS cells and/or depleted of nonneoplastic 

lymphocytes 

● Abundant histiocytes 

● Often mistaken for aggressive forms of other B- 

cell or T-cell lymphomas 

Demographics 

● Rarest CHL subtype 

● Males commonly affected 



● Retroperitoneal lymph nodes, abdominal organs, 

and bone marrow 

● Peripheral lymphadenopathy may also be 

seen 


● Widespread involvement (including the 

subdiaphragmatic region and bone marrow at 

diagnosis) 

● B symptoms 


Lymph Node 

● Highly variable appearance 

● Relative predominance of neoplastic HRS cells 

and scarcity of background lymphocytes 

● Two patterns (diffuse fibrosis and reticular) 

First pattern 

● Diffuse fibrosis with prominent fibroblastic 

proliferation; however well-formed fibrous bands 

are absent 

● Many histiocytes and some small lymphocytes, 

but usually lack significant numbers of plasma 

cells or eosinophils 

Second pattern 

● Neoplastic cells with anaplastic and pleomorphic 

features 



● Co-expression of CD30 and PAX5 (distinguishes 

from ALK-negative ALCL) 

● Either OCT2 or BOB1 may be expressed in HRS 

cells 

● CD79a negative 

● EBV-positive DLCBL with HRS–like cells is to be 

considered if there is a strong expression of B-cell 

markers such as CD20 and CD79 

EBV/LMP1 

● Frequently positive 

GENETICS 

● IGH gene rearrangement shows B-cell clonality, 

which can be more readily detected due to the 

relative abundance of tumor cells 


Prognosis 

● Aggressive behavior 

● Patients who underwent more-intensive therapy 

regimens appeared to do far better 

● LDCHL patients benefit from treatment with 

dose-intensive treatment strategies 

LYMPHOCYTE-RICH CHL 

INTRODUCTION 

● CHL with scattered HRS cells and a nodular or 

(less often) diffuse cellular background 

consisting of small lymphocytes and absence of 

neutrophils and eosinophils 

Demographics 

● Median patient age similar to that of NLPHL, 

older than seen in other CHL 

● Males commonly affected 


● Peripheral lymph nodes 

● Mediastinal involvement and bulky disease 

uncommon 


● Stage I or II diseases 

● B symptoms are rare 


Lymph Node 

Nodular pattern (common) 

● Nodules of small lymphocytes ± small 

eccentric/ regressed germinal centers 

● HRS cells are found within the nodules, but 

outside of the germinal centers 


● T-zone attenuated 

● Eosinophils and/or neutrophils are absent from 

the nodules, or if present, are located in the 

interfollicular zones and are few in number 

● HRS cells: Mononuclear lacunar cells or 

lymphocyte predominant (LP) cells 

● LRCHL type nodules surrounded by fibrous 

bands with randomly distributed HRS cells in T- 

cell–rich zones can be seen, and typing of 

these cases as NSCHL might be more 

appropriate (possible relationship between the 

LRCHL and NSCHL) 

Nodules 

● Small lymphocytes in the nodules which have 

the features of mantle cells (IgM+ and IgD+), an 

evidence that the nodules are expanded mantle 

zones 

● Eccentrically located, small, germinal centers, 

highlighted by a dense meshwork of CD21+ FDC 

(intact germinal centers are infrequent in NLPHL) 

● No CD15 positive granulocytes in expanded 

mantle zones, but may be present in 

interfollicular zones 

EBV LMP1 

● More frequently than in nodular sclerosis CHL, 

but less frequently than in mixed cellularity CHL 

(MCCHL>> LRCHL>>NSCHL) 


● Similar to that of NLPHL 

● Relapses are more common in NLPHL than in 

LRCHL 

● Better than those of the other CHL subtypes 

Figure 8 

Diffuse pattern (rare): 

● Small lymphocytes of the cellular background 

may be admixed with histiocytes with or without 

epithelioid features 


Neoplastic cells 

● CHL immunophenotype (CD30+, CD15+/−, 

IRF4/MUM1+, PAX5+/−, CD20−/+, J chain−, 

CD75−, PU1−, EBV/LMP1+ for EBV harboring 

cases) 

● This helps distinguish LRCHL from NLPHL 

● B-cell transcription factor expression (OCT2, 

BOB1, and BCL6) is more frequent in LRCHL than 

in the other CHL subtypes 

● TFH rosettes (PD1/CD279+, CD57−/+) around the 

neoplastic cells can be seen in approximately half 

of the cases 



Chapter 8: Acute Myeloid 

Leukemia In A Nutshell and Related 

Precursor Neoplasms 


Myeloid Maturation 

Kshitija Kale Akanksha Gupta 


Chapter 8.1: Acute Myeloid Leukemia with Recurrent 

Genetic Abnormalities 

INTRODUCTION 

● Recurrent genetic abnormalities in acute myeloid 

leukemia (AML) are associated with distinctive 

clinicopathological features and have prognostic 

significance 

● Common abnormalities: 

‣ t(8;21)(q22;q22.1 ) 

‣ inv(16)(p13.1;q22) or t(16;16)(p13.1;q22) 

‣ t(15;17)(q24.1;q21.2) 

‣ t(9;11)(p21.3;q23.3) 

● AML with t(8;21)(q22;q22.1), AML with 

inv(16)(p13.1q22) or t(16;16)(p13.1;q22), and 

acute promyelocytic leukemia with PML-RARA 

are considered to be acute leukemias without 

regard to blast cell count 

ACUTE MYELOID LEUKEMIA WITH t(8;21)(q22;q22.1) 

RUNX1-RUNX1T1 

● AML showing predominantly neutrophilic 

maturation 

Demographics 

● Younger adults 


● Myeloid sarcoma may be present at the 

presentation 


● Large myeloblasts with abundant basophilic 

cytoplasm, salmon-colored azurophilic granules 

(Fig 2), perinuclear hof, Auer rods, background 

myeloid dysplasia, no monocytes, eosinophil 

precursors may be increased 


Figure 2 

Picture courtesy: Chandra Krishnan, MD @Hematogones 

● Few blasts show large granules (pseudo-Chediak 

- Higashi granules) 

● Auer rods are frequently found & appear as 

single long sharp rods with tapered ends (Fig 1) 

● Promyelocytes, myelocytes, and mature 

neutrophils with variable dysplasia are present in 

the bone marrow 

● Erythroblasts and megakaryocytes have normal 

morphology 


● Positive: CD34, HLA-DR, MPO and CD13, CD15 

and CD65, CD19, PAX5, CD79a 

● CD56 may be positive (poor prognosis) 

Picture credit: VSantiago @vichemecytopath 

Figure 1 

Figure 3 


GENETICS 

● t(8;21)(q22;q22.1) involves RUNX1, which 

encodes the alpha subunit of CBF, and 

RUNX1T1 

● RUNX1-RUNX1T1 fusion transcript is 

consistently seen in patients with 

t(8;21)(q22;q22.1) AML 

● Others include loss of a sex chromosome or 

del(9q) with loss of 9q22 and KIT mutations 


● A high rate of complete remission and longterm 

disease-free survival on treatment with 

cytarabine 

● CD56, KIT positivity implies a poor prognosis 

ACUTE MYELOID LEUKEMIA WITH inv(16){p13.1q22) 

or t(16;16) {p13.1;q22); CBFB-MYH11 

● AML with monocytic or granulocytic 

differentiation and characteristically abnormal 

eosinophil component 

Demographics 

● Younger adults 


● Myeloid sarcoma may be present 

● WBC count significantly higher than t(8;21) 

MORPHOLOGY AND PHENOTYPE (Fig 4) 

● Usually increased eosinophils in all stages of 

maturation, abnormal large purple basophil-like 

eosinophilic granules, may obscure cell 

morphology 

● Auer rods may be present, peripheral blood 

eosinophils not increased 


● Complex, blast population with CD34 & CD117 

● Granulocytic lineage: CD13, CD33, CD15, CD65 

● Monocytic lineage: CD14, CD11b, CD11c, CD64 

Picture Credit: KDannheim @KDannheimMD 

Figure 4 

GENETICS 

● inv(16) and t(16;16) result in the fusion of CBFB 

at 16q22 to MYH11 at 16p13.1 


● A high rate of complete remission and favorable 

overall survival 

● Poor prognosis: old age, leukocytosis, FLT3-TKD, 

trisomy 8 

ACUTE PROMYELOCYTIC LEUKEMIA (APL) WITH PML- 

RARA 

● AML showing predominantly promyelocytes 

● Two variants: Hypergranular and microgranular 

(hypogranular) 

Demographics 

● Middle-aged adults 


● Disseminated intravascular coagulation (DIC) in 

both variants, higher leukocyte count and 

shorter doubling time in microgranular 


● Abnormal promyelocytes show bilobed kidney bean 

nuclei, densely packed or coalescent large 

cytoplasmic granules, staining bright pink, red, or 

purple on Romanowsky 

● Auer rods characteristically present, single, or 

multiple (Faggot cells – Fig 5) 


● Low or absent HLA-DR, CD34, CD11a, CD11b, and 

CD18 

● CD15 only weakly expressed or negative 

● Microgranular: CD2, CD34 in some cells, CD56 (poor 

prognosis) 

Figure 8 

Picture Credit: Sara Javidiparsijani @javidiparsijani 

Figure 5 

Figure 6 

Figure 7 

● Microgranular (hypogranular) APL: apparent 

paucity or absence of granules and 

predominantly bilobed nuclei (Fig 6,7) 


● Positive: CD33 (bright), CD13 (heterogenous) and 

KIT (CD117), CD64 

GENETICS 

● PML-RARA fusion: RARA gene on 17q21.2 fuses 

with a nuclear regulatory factor gene on 

15q24.1 (PML) 

● Cryptic or masked t(15;17): cytogenetically 

cryptic and detected on molecular studies 

● Gain of chr 8, FLT3-ITD, TKD 

● VARIANT APL: cases with t(11;17) resulting in 

ZBTB16-RARA. They show some morphological 

differences with a predominance of cells with 

regular nuclei, many granules, usually an 

absence of Auer rods, an increased number of 

pelgeroid neutrophils, strong MPO activity and 

resistance to tretinoin 


● Responds to tretinoin and arsenic oxide 

● Poor prognosis: hyperleukocytosis, CD56 

expression, FLT3-ITD mutation, and older 

patient age 


ACUTE MYELOID LEUKEMIA WITH 

t(9;11)(p21.3;q23.3); KMT2A-MLLT3 

● AML with 20% PB or BM blasts (required), with 

KMT2A-MLLT3 fusion and monocytic features 

Demographics 

● More common in children 


● Extramedullary sarcoma, tissue infiltration 

(gingiva, skin), DIC 


● Anemia and thrombocytopenia, and often 

pancytopenia 


● Most commonly AML with maturation and 

acute myelomonocytic leukemia 

● Auer rods are present in approximately 1/3 of 

cases 

● Marrow and peripheral blood basophilia, defined 

as 2% basophils 


● Monoblasts and promonocytes, strongly positive 

for non-specific esterase, absent MPO 


● Pediatric: CD33, CD65, CD4, and HLADR, but 

CD13, CD34, and CD14 is usually low 

● Adult: CD14, CD4, CD11b, CD11c, CD64, CD36, 

and lysozyme 

GENETICS 

● t(9;11)(p21.3;q23.3), involving MLLT3 (AF9) is 

the most common KMT2A translocation 

● Secondary cytogenetic abnormalities: gain of 

chromosome 8 


● Intermediate survival 

● Superior to that of AML with other 11q23.3 


● Overexpression of MECOM: poor prognosis 

ACUTE MYELOID LEUKEMIA WITH t(6;9)(p23;q34. 1); 

DEK-NUP214 

● AML with 20% PB or BM blasts (required) with 

or without monocytic features 

● Associated with basophilia and multilineage 

dysplasia 

Demographics 

● Affects both adults and children 

Figure 9: 

Arrow: Basophils 

Picture credit: Michael Bayerl @MGBayerl_MD 


● MPO, CD9, CD13, CD33, CD38, CD123, and 

HLA-DR, KIT (CD117), CD34, and CD15 

● Some cases express the monocyte-associated 

marker CD64, and some are TdT-positive 

GENETICS 

● Fusion of DEK on chromosome 6 with NUP214 

(also called CAN) on chromosome 9 

● FLT3-ITD mutations are also common 


● High WBC counts are most predictive of shorter 

overall survival, and increased bone marrow 

blasts are associated with shorter disease-free 

survival 

ACUTE MYELOID LEUKEMIA WITH inv(3)(q21.3q26.2) 

or t(3;3)(q21.3;q26.2); GATA2 - MECOM 

● Deregulated MECOM (also called EVI1) and 

GATA2 expression 


● ≥20% PB or BM blasts (required) 

● Shows normal or elevated platelet counts, 

increased dysplastic megakaryocytes with 

unilobed or bilobed nuclei and multilineage 

dysplasia 

Demographics 

● Affects adults 


● Anemia with mostly a normal platelet count, 

but marked thrombocythemia in few cases 


● PB: Hypogranular neutrophils with a pseudo- 

Pelger-Huët anomaly, giant and hypogranular 

platelets, bare megakaryocyte nuclei 

● Blasts: Morphologies of AML without 

maturation, acute myelomonocytic leukemia, 

and acute megakaryoblastic leukemia are most 

common 

● Megakaryocytes may be normal or increased in 

number with many small non-lobated or 

bilobed forms or dysplastic megakaryocytic 

forms may occur 

● Dysplasia of maturing erythroid cells and 

neutrophils is also common. Marrow 

eosinophils, basophils, and/ or mast cells may 

be increased 

Picture: Siba El Hussein @SibaElHussein 

Figure 10 


● Positive: CD34, CD33, CD13, KIT (CD117), and 

HLA-DR; CD38, with aberrant CD7 expression 

● Monocytic/Megakaryocytic markers 

GENETICS 

● MECOM, monosomy 7, RAS/receptor tyrosine 

kinase 

● Cases with both t(9;22)(q34.1;q11.2) and inv(3) 

(q21.3q26.2) or t(3;3)(q21.3;q26.2) at 

presentation are best classified as an aggressive 

phase of chronic myeloid leukemia, rather than 

AML with inv(3) or t(3;3) 


● Prognosis: poor, worse with complex karyotype, 

monosomy 7 

ACUTE MYELOID LEUKEMIA (MEGAKARYOBLASTIC) 

WITH t(1;22) (p13.3;q13.1); RBM15-MKL1 

● AML showing maturation in the megakaryocyte 

lineage 

Demographics 

● Infants without Down syndrome (Down 

syndrome should be excluded), female 

predominance, common in first six months of life 


● Organomegaly: hepatosplenomegaly, anemia, 

thrombocytopenia, leukocytosis, 

megakaryoblastic blasts with undifferentiated 

blasts 

● Medium to large, indented irregular nucleus, 1-3 

nucleoli, blebs are seen, pseudopod formation 

● Micromegakaryocytes present 

● Collagen dense fibrosis present in marrow, mimics 

metastasis 

● Aspirate may be dry, correlate with biopsy 


● Positive: CD41, CD61, CD42B, CD36 

● Negative: CD34 AND HLA-DR 

GENETICS 

● In most cases, t(1;22)(p13.3;q13.1) is the only 

karyotypic abnormality 

PROGNOSIS: Poor 


ACUTE MYELOID LEUKEMIA WITH BCR-ABL1 

● De novo AML in which patients show no 

evidence (either before or after therapy) of 

chronic myeloid leukemia (CML) (Refer Table 1) 

● Exclude MPAL, RGA, therapy-related myeloid 

neoplasms 

Demographics 

● Adults, males 


Table 1 

AML with BCR/ABL 

Low M:E 

Dwarf megakaryocytes 

absent 

Less frequent 

splenomegaly, basophilia 

NPM1, FLT3 

Not driven by the mutation 

primarily, TKI may/may not 

be effective 

CML with BCR/ABL 

High M:E 

Dwarf megakaryocytes 

present 

Common 

Less common 

Driven by BCR-ABL1, TKI 

is effective 

● Bone marrow and peripheral blood myeloblasts, 

with features ranging from those of minimal 

differentiation to those of granulocytic 

maturation 


● Myeloid antigens (CD13 and CD33) and CD34 

● Aberrant expression of CD19, CD7, and TdT 

appears to be common 

AML WITH MUTATED NPM1: POINT MUTATION 

● AML with myelomonocytic or monocytic 

features and typically presents de novo in adults 

with a normal karyotype 

● Cytoplasmic NPM (nucleophosmin) staining is 

diagnostic 

● Recurrent genetic lesion but separate entity 

Demographics 

● Affects adults, female predominance 


● Anemia, thrombocytopenia, leukocytosis, 

extramedullary disease in the gingiva, lymph 

nodes 


● Diagnosis: identification of the genetic lesion by 

molecular techniques and/or IHC in paraffin 

sections of aberrant cytoplasmic expression of 

NPM1 

● Multilineage dysplasia 

● Cup-like blasts (Fig 11,12) 

● Hypercellular bone marrow 

Figure 11 

GENETICS 

● All cases demonstrate t(9;22) (q34.1;q11.2) or 

molecular genetic evidence of BCR-ABL1 fusion 

● Most cases demonstrate the p210 fusion 

● Others include loss of chromosome 7, gain of 

chromosome 8, and complex karyotypes 

PROGNOSIS 

● Aggressive disease, with poor response to 

traditional AML therapy or tyrosine kinase 

inhibitor therapy alone 


Figure 12 

GENETICS 

● Karyotype normal but del 9q, trisomy 8 seen 

PROGNOSIS 

● Good prognosis: NPM1, normal karyotype, absent 

FLT3, younger patients 

● Poor prognosis: old age, FLT3 mutation 


● CD13+, CD33+; CD34 usually negative 

● MAJOR SUBGROUPS: a) myeloid without 

maturation, b) monocytic 

● CD34+/ CD25+/ CD123+/ CD99+ is associated 

with FLT3 mutation 

Figure 13 

AML WITH BIALLELIC MUTATION OF CEBPA 

● AML with maturation or AML without 

maturation, some cases show myelomonocytic or 

monoblastic features. This leukemia usually 

presents de novo 

Demographics 

● Children, young adults 


● Higher hemoglobin levels, lower platelet counts 

and lower lactate dehydrogenase levels than 

CEBPA-wildtype AML 

● Lower frequency of lymphadenopathy and 

myeloid sarcoma 


● No distinctive morphological features 

● Multilineage dysplasia in some cases 


● Biallelic mutation of CEBPA - higher frequency of 

HLA-DR, CD7, and CD15; lower frequency of CD56 

expression than with a single mutation 

GENETICS 

● Most cases - normal karyotype, if abnormaldel(9q) 

is common and does not influence 

prognosis 

PROGNOSIS 

● Good prognosis, similar to that of AML with 

inv(16) (p13.1q22) or t(8;21) 

ACUTE MYELOID LEUKEMIA WITH MUTATED RUNX1 

● De novo leukemia with ≥20% bone marrow or 

peripheral blood blast cells 


● Morphological features of most AML, NOS, 

categories 

● Higher frequency among cases with minimal 


● Cases with a history of prior radiation therapy, 

MDS, or a myelodysplastic/ myeloproliferative 

neoplasm may also show RUNX1 mutations but 

are excluded from this category 


● Lower hemoglobin and lactate dehydrogenase 

levels and lower white blood cell and peripheral 

blood blast cell counts than patients with 

wildtype RUNX1 


● No specific morphology 


● CD13, CD34, and HLA-DR, with variable 

expression of CD33, monocytic markers, and MPO 

GENETICS 

● RUNX1 mutations 

● Cooperating mutations: ASXL1, KMT2A, FLT3-ITD, 

IDH1 R132, and IDH2 R140 and R172 

● Counseling: Affected family members may have 

autosomal dominant thrombocytopenia and 

dense granule platelet storage pool deficiency, as 

well as an increased risk of development of AML 

or MDS 

PROGNOSIS 

● Prognosis: worse overall survival 

● Combination of RUNX1 and ASXL1 mutations 

associated with an adverse prognosis 


Table 1: Acute Myeloid Leukemia with Recurrent Genetic Abnormalities 

AML with t(8;21) 

(q22;q221.) RUNX1- 

RUNXT1 

AML with inv 16 

(p13.1;q22) or 

t(16;16) (p13.1;q22) 

CBFB-MYH11 

APL 

with 

PML-RARA 

AML with t(9;11) 

(p21.3; q23.3) 

KMT2A-MLLT3 


(p23; q34.1) 

DEK-NUP214 

AML with inv3 

(q21.3; q26.2) or 

t(3;3) 

(q21.1; q26.2) 

GATA2- 

MECOM 


(p13.3; q13.1) 

RBM15-MKL1 

AML with BCR-ABL1 

AML with mutated 

NPM1 

AML with 

Biallelic mutations 

with CEBPA 


RUNX1 

Demographics and clinical 

presentation 

• Young adults 

• Young adults 

• High WBC count 

• Middle aged 

• DIC 

• High TLC (especially 

microgranular APL) 

• Children 

• DIC 

• Tissue infiltration 

(gingiva, skin) 

• Extramedullary sarcoma 

• Adults, children 

• Pancytopenia 

• Adults 

• Anemia, 

Thrombocythemia +/- 

• Infants (until 6 months) 

• Females 

• Organomegaly 

• Adult males 

• De novo, no H/O CML 

• Splenomegaly and 

basophilia are rare 

• Adult females 

• Anemia 

• Leukocytosis 

• Thrombocytopenia 

• Extramedullary 

involvement: gingiva, LN 

• Children and young adults 

• Raised Hb level 

• Reduced platelet count 

• Low levels of LDH 

• Low Hb, low LDH, low TLC 

Morphology Immunophenotyping Genetics Prognosis 

• Neutrophilic 

maturation 

• Large blasts, large 

granules, Auer rods 

present (M2-like) 

• Dysplastic eosinophils 

With arge purple 

basophil-like granules 

• M4-like 

• Hypergranular 

(Auer rods noted) 

• Microgranular 

• Monoblasts 

• Promonocytes 

• M5-like 

• Myelomonocytic 

(M4) 

• Auer rods -/+ 

• Basophilia noted 

• Hypergranular 

neutrophils 

• Pseudo-Pelger Huët 

• Giant hypogranular 

platelets 

• Megs: large nuclei, 

dysplastic 

• Myelomonocytic and 

megakaryoblastic 

• Megakaryoblasts 

• Micromegakarocytes 

• BM fibrosis (dry tap) 

• Myeloblasts 

• Cup-like blasts 

• BM: hypercellular 

with multilineage 

dysplasia 

• IHC: NPM1 

cytoplasmic 

• Few Cases: 

multilineage 

dysplasia 

• CD34, HLA-DR, MPO, 

CD13, CD15, CD65 

• Retained expression of 

CD19, PAX5, CD79a 

• CD56 expression 

• CD34, CD117, CD13, 

CD33, CD15, CD65, CD14, 

CD11b, CD11c, CD64 

• CD33 bright 

• CD13, CD117, CD64 

• Absent: HLA-DR, CD34, 

CD11a, CD11b, CD18 

• Microgranular: CD2, 

CD34+, CD56 

• Absent MPO 

• Pediatric: CD33, CD65, 

CD4, HLA-DR 

• CD13/33/14: low 

expression 

• Adult: CD14, CD4, CD11b, 

CD11c, CD64, CD36, 

lysozyme 

• MPO, CD13, CD33 

• CD9, CD123, CD34, CD15, 

HLA-DR, CD117 

• CD64 (monocytic) 

• TDT positive 

• CD34, CD33, CD13, 

CD117, HLA-DR, CD38 

• Aberrant expression of 

CD7 

• CD41, CD61, CD42B, CD36 

• Negative: CD34 and HLA- 

DR 

• CD13, CD33, CD34, 

aberrant expression of 

CD19, CD7, TDT 

• CD13, CD33 

• CD34 usually negative 

• If CD34+/ CD25+/ 

CD123+/ CD99+ are 

positive, then associated 

with FLT3 mutations 

• HLA-DR, CD7, CD15 

positive 

• CD13, CD34, HLA-DR 

• CD33: variable expression 

• RUNX1-RUNX1T1 fusion 

• Del 9q 

• Loss of 9q22 

• KIT mutation 

• CBFB (16q22) fuses with 

MYH11 (16p13.1) 

• FLT3-TKD mutations 

• Trisomy 8 

• t(15;17) PML-RARA 

• t(11;17) ZBTB16-RARA 

• Gain of chr 8 

• FLT3-ITD 

• MLLT3 (AF9) fuses with 

KMT2A 


• DEK (6p23) fuses with 

NUP214 (CAN) (9q34.1) 

• FLT-ITD mutations 

• MECOM 

• Monosomy 7 

• RAS/Receptor TK 

• t(1;22) (p13.3; q13.1) 

• p210 fusion of BCR-ABL1 

• Loss of chr 7 


• Complex karyotype 

• NPM1 mutations 

• Del 9q 

• Trisomy 8 

• CEBPA mutations, Del 9q 

• RUNX1 Mutations 

• Associated mutations: 

ASXL1, KMT2A, FLT3-ITD, 

IDH 

• Good 

• If CD56+ and KIT 

mutations: poor 

prognosis 

• Favorable 

• Poor prognosis with old 

age, leukocytosis, FLT3 

and Trisomy 8 

• Responds well to 

tretinoin, arsenic oxide 

• Poor prognosis with 

leukocytosis, CD56, 

FLT3-ITD 

• Intermediate 

• If MECOM is expressed: 

poor prognosis 

• If high TLC and more 

blasts: short survival 

• Poor 

• Complex karyotype or 

monosomy 7: worse 

prognosis 

Poor 

• Aggressive course 

• Good 

• Poor prognosis with old 

age and FLT3 mutations 

• Good 

• Worse 

• Worst if associated with 

ASXL1 mutations 


Chapter 8.2: Acute Myeloid Leukemia with Myelodysplasia- 

Related Changes 

Table 1: WHO CRITERIA for AML-MRC 

The diagnosis of AML-MRC requires that the following 

three criteria be met: 

1) ≥20% blood or marrow blasts 

2) Any of the following: 

● History of myelodysplastic syndrome or 

myelodysplastic/myeloproliferative neoplasm 

● Myelodysplastic syndrome-related cytogenetic 

abnormality (Table 1) 

● Multilineage dysplasia* 

3) Absence of both of the following: 

● Prior cytotoxic or radiation therapy for an 

unrelated disease 

● Recurrent cytogenetic abnormality 

*Multilineage dysplasia alone is insufficient for a 

diagnosis of AML-MRC in a de novo case of AML with 

mutated NPM1 or biallelic mutation of CEBPA 

Reprinted with permission from WHO Classification of Tumors, Revised 

4th Edition, Volume 2, Swerdlow SH et al. Acute myeloid leukemia with 

myelodysplasia-related changes, Page No. 150, 2017 

INTRODUCTION 

● Acute leukemia with ≥20% peripheral blood or 

bone marrow blasts with morphological features 

of myelodysplasia in >50% cells in at least two 

cell lines, or occurring in patients with a prior 

history of myelodysplastic syndrome (MDS) or 

myelodysplastic/myeloproliferative neoplasm 

(MDS/MPN), with MDS-related cytogenetic 

abnormalities 

Demographics 

● Elderly, rare in children 


● Peripheral blood, bone marrow 


● Severe pancytopenia, refractory anemia 

● Cases with 20-29% blasts, especially cases arising 

from MDS or in childhood, maybe slowly 

progressive 


● >50% dysplasia, at least two cell lines, if the 

diagnosis is based upon morphology alone 

● AML after treatment shows dysplasia, do not call 

MRC, cytogenetics is key 

Nupur Sharma 


● Dysgranulopoiesis: Neutrophils with 

hypogranular cytoplasm, hyposegmented nuclei 

(pseudo-Pelger Huët anomaly) or bizarrely 

segmented nuclei 

● Dyserythropoiesis: Megaloblastosis, karyorrhexis, 

and nuclear irregularity, fragmentation or 

multinucleation, ring sideroblasts, cytoplasmic 

vacuoles, and periodic acid- Schiff (PAS) positivity 

in erythroblasts (normal erythroids are not PAS+) 

● Dysmegakaryopoiesis: Micromegakaryocytes and 

normal-sized or large megakaryocytes with nonlobated 

or multiple nuclei 

● Micromegakaryocytes: usually size of a 

promyelocyte, has platelets inside (sometimes 

difficult to see, CD41, CD61 may be required) 

● Differential diagnosis: MDS with excess blasts, 

pure erythroid leukemia, acute megakaryoblastic 

leukemia, and AML, not otherwise specified (NOS) 

● Cytogenetic categorization takes precedence 

before diagnosing a case as AML-MRC 


● Aberrant phenotypes: Increase in CD14 

expression on blasts: poor prognosis, increased 

expression of CD11b, CD34 

● Decreased expression of HLA-DR, KIT (CD117), 

FLT3 (CD135) and CD38 and increased expression 

of lactoferrin are associated with the presence of 

multilineage dysplasia 

● Increased ABCB1 (also called MDR1) in the blast 

cells 

● Aberrant CD7 and CD56 

● CD13, CD33: aberrantly high/low 

GENETICS (Refer Table 2) 

● Complex karyotype, loss of chromosome 

7/del(7q), del (5q) and unbalanced translocations 

involving 5q 


● t(3;5) (associated with multilineage dysplasia and 

younger patient age at presentation) 

● ASXL1 and TP53 mutations 

Table 2: Cytogenetic abnormalities sufficient for the diagnosis of 

AML-MRC. 

Complex karyotype (≥3 abnormalities) 

Unbalanced abnormalities 

• Loss of chromosome 7 or del(7q) 

• del(5q) or t(5q) isochromosome 17q or t(17p) 

• Loss of chromosome 13 or del(13q) 

• del(11q) del(12p) or t(12p) 

• idic(X)(q13) 

Balanced abnormalities 

• t(11;16)(q23.3;p13.3) 

• t(3;21)(q26.2;q22.1) 

• t(1;3)(p36.3;q21.2) 

• t(2;11)(p21;q23.3) 

• t(5;12)(q32;p13.2) 

• t(5;7)(q32;q11.2) 

• t(5;17)(q32;p13.2) 

• t(5;10)(q32;q21) 

• t(3;5)(q25.3;q35.1) 

Reprinted with permission from WHO Classification of Tumors, 

Revised 4th Edition, Volume 2, Swerdlow SH et al. Acute myeloid 

leukemia with myelodysplasia-related changes, Page No. 151, 

2017 

PROGNOSIS 

● Lower rate of complete remission than in other 

AML subtypes 

● Poor prognosis: Multilineage dysplasia with TP53 

loss, increased CD14 expression, balanced 11q 

abnormality, ASXL1, balanced translocation 3 or 

7q loss 


Chapter 8.3: Therapy-Related Myeloid Neoplasms 

INTRODUCTION 

● Neoplasms that occur as a late complication of 

cytotoxic chemotherapy and/or radiation 

therapy administered for a prior neoplastic or 

non-neoplastic disorder (Table 1) 

● Includes therapy-related cases of acute myeloid 

leukemia (t-AML), myelodysplastic syndromes (t- 

MDS), and myelodysplastic/myeloproliferative 

neoplasms (t-MDS/MPN) 

● Excluded from this category: Progression of 

myeloproliferative neoplasms (MPNs) and 

evolution of primary MDS or primary MDS/MPN 

to AML (so called 'secondary' AML). In each of 

these cases, evolution into AML is a natural 

progression 

Table 1: Two major classes of therapy-related myeloid neoplasms 

Nupur Sharma 


Demographics 

● Most patients have a history of treatment for a 

solid tumor and some for a hematological 

neoplasm, commonly breast cancer and non- 

Hodgkin lymphoma 

● Few cases have a history of therapy for a nonneoplastic 

disorder, and a similar proportion of 

cases occur following high-dose chemotherapy 

and autologous hematopoietic cell 

transplantation for a previously treated, nonmyeloid 

neoplasm 


● Blood and bone marrow 

● Extramedullary myeloid sarcoma has also been 

reported 


● Two subtypes clinically recognized (Table 1) 

Alkylating agent class Topoisomerase II 

inhibitor class 

Cytogenetics del 5(q), -7/del 7(q) * t(11q23.3) 

t(21q22.1) 

Frequency ~70% t-MN patients ~30% t-MN patients 

Latency 5-7 years 2-3 years 

Presentation MDS AML 

Implicated 

drugs 

Alkylating agents: 

Melphalan, 

cyclophosphamide, 

nitrogen mustard, 

chlorambucil, 

bendamustine, 

busulfan, dacarbazine, 

procarbazine, 

carmustine, mitomycin 

C, thiotepa, lomustine 

Platinum-based: 

carboplatin, cisplatin 

Antimetabolite: 

Azathioprine, 

fludarabine 

Anthracyclines: 

doxorubicin, 

daunorubicin, 

epirubicin. 

Other topoisomerases 

II inhibitors: 

mitoxantrone, 

etoposide, teniposide 

*Loss of the short arm of chromosome 17 containing the TP53 gene 

due to del (17p), unbalanced rearrangement, or -17, is observed in 

association with a del(5q) in 40% of cases 


● Most patients present with AML or MDS 

associated with multilineage dysplasia 

GENETICS 

● t-MDS: Unbalanced chromosomal aberrations, 

most commonly partial loss of 5q, loss of 

chromosome 7, or a deletion of 7q 

● t-AML: Balanced translocation including 

t(9;11), t(11;19), t(8;21), t(3;21), t(15;17), and 

inv(16) 




Chapter 8.4: Acute Myeloid Leukemia, Not Otherwise 

Specified (AML, NOS) 

INTRODUCTION 

● Neoplasms that fulfill the general criteria for AML, 

but lack: 

‣ Recurrent genetic or molecular abnormality 

‣ Prior chemotherapy 

‣ Myeloid dysplasia involving majority of the 

cells 

‣ MDS-type cytogenetic abnormalities 

‣ Association with Down syndrome 

‣ History of MDS or MDS/MPN 

SUBTYPES 

M0: AML with minimal differentiation 

M1: AML without maturation 

M2: AML with maturation 

M4: Acute myelomonocytic leukemia 

M5: Acute monocytic or monoblastic leukemia 

M6: Pure erythroid leukemia 

M7: Acute megakaryoblastic leukemia 

Acute basophilic leukemia 

Acute panmyelosis with myelofibrosis 

Nupur Sharma Rama Devi Aakash Bhatia Akanksha Gupta 

● Cytochemical staining for/with MPO, Sudan Black 

B, and naphthol AS-D chloroacetate esterase 

(CAE) is negative (i.e., 90% 

blasts without significant evidence of maturation 

to more mature neutrophils 

● Maturing cells of the granulocytic lineage 

constitute

Demographics 

● Older adults 


● Anemia, thrombocytopenia, and neutropenia 

● Some patients present with leukocytosis and 

numerous circulating blasts 


● Myeloblasts with azurophilic granules and/ or 

delicate Auer rods 

● In other cases, the blasts resemble lymphoblasts 

and lack azurophilic granules 

● MPO and Sudan Black B positivity always ≥3% 

Differential diagnosis: 

● Lymphoblastic leukemia (ALL) in cases with blast 

cells lacking granules or that have a low 

percentage of MPO-positive blasts 

● AML with maturation in cases with a higher 

percentage of MPO-positive blasts 


● Positive: MPO and one or more myeloidassociated 

antigens, such as CD13, CD33, and 

KIT (CD117) 

● CD34 and HLA-DR are positive in most cases 

● Negative: B-cell and T-cell cytoplasmic lymphoid 

markers cCD3, cCD79a, and cCD22 

● Also negative for CD15 and CD65 (mature 

granulocytic markers) and CD14 and CD64 

(mature monocytic markers) 

● No specific genetic abnormalities 

AML WITH MATURATION (M2) 

● ≥20% blasts in the bone marrow or peripheral 

blood and evidence of maturation (with ≥10% 

of maturing cells of granulocytic lineage) in 

the bone marrow; cells of monocyte lineage 

constitute

● Monoblasts: large cells with moderate to intense 

basophilic cytoplasm, scattered fine azurophilic 

granules, vacuoles 

● May show pseudopod formation with more 

folded convoluted nuclear contours, delicate lacy 

open chromatin with one or more prominent 

nucleoli 

● Promonocytes have a more irregular and 

delicately convoluted nuclear configuration; 

cytoplasm is usually less basophilic and 

sometimes more obviously granulated, with 

occasional large azurophilic granules and 

vacuoles 

Figure 2 

Cytochemistry 

● At least 3% of the blasts should show MPO 

positivity 

● Monoblasts, promonocytes, and monocytes 

are positive for non-specific esterase 

● Double staining for non-specific esterase and 

naphthol AS-D chloroacetate esterase (CAE) or 

MPO may reveal dual-positive cells 

DIFFERENTIAL DIAGNOSES 

● AML with maturation (M2), acute monocytic 

leukemia (M5b), and chronic myelomonocytic 

leukemia (CMML) 

● Differential diagnosis with chronic 

myelomonocytic leukemia is critical; it relies on 

the proper identification of blasts and 

promonocytes, which may be increased only in 

the bone marrow. (MPO cytochemistry can be 

used to give a more accurate differential count 

for myelocytic/monocytic components) 


● Positive: CD13, CD33, CD65, and CD15 

● Monocytic: ≥2 of the following: NSE, CD14, CD64, 

CD11c, lysozyme 

● Others: CD11b, CD4, CD36, CD68 (PGM1), CD163 

ACUTE MONOBLASTIC & MONOCYTIC LEUKEMIA (M5) 

● Peripheral blood or bone marrow has ≥20% 

blasts (including promonocytes), and ≥80% of the 

leukemic cells are of monocytic lineage, including 

monoblasts, promonocytes, and monocytes; a 

minor neutrophil component (

● Distinguishing from chronic myelomonocytic 

leukemia is critical; it relies on the proper 

identification of promonocytes and their 

inclusion as blast equivalents 

● The abnormal promyelocyte in APL show intense 

MPO and naphthal AS-D chloroacetate esterase 

(CAE) positivity, whereas the monocytes are 

weakly reactive or negative 


Figure 4 

Figure 3 

● Monoblasts are large cells with abundant 

cytoplasm that can be moderate to intensely 

basophilic and may show pseudopod formation 

● Scattered fine azurophilic granules and vacuoles 


● Round nuclei with delicate lacy chromatin and 

one or more large prominent nucleoli 

● Promonocytes have a more irregular and 

delicately convoluted nuclear configuration; 

cytoplasm is usually less basophilic and 

sometimes more granulated, with occasional 

large azurophilic granules and vacuoles 

● Hemophagocytosis (erythrophagocytosis) may 

be seen and is associated with 

t(8;16)(p11.2;p13.3) 

● Bone marrow: hypercellular with a predominant 

population of large, poorly differentiated blasts 

with abundant cytoplasm 

● Extramedullary lesions may be composed 

predominantly of monoblasts or promonocytes 

or an admixture of two cell types 

● Differential diagnosis: AML without maturation, 

AML with minimal differentiation, AML with 

t(9;11)(p21.3;q23.3), and acute megakaryoblastic 

leukemia 

● Major differential diagnoses of acute monocytic 

leukemia include chronic myelomonocytic 

leukemia, acute myelomonocytic leukemia, and 

microgranular acute promyelocytic leukemia 

● Positive: CD13, CD33, CD15, and CD65 

● Positive for at least two markers of monocytic 

differentiation, such as CD14, (positive in mature 

monocytes and negative in promonocytes) CD4, 

CD11b, CD11c, CD64 (bright), CD68, CD36 

(bright), and lysozyme 

● Most cases are positive for HLA-DR 

● MPO can be expressed in acute monocytic 

leukemia and less often in monoblastic leukemia 


● Aberrant expression of CD7 and/or CD56 is seen 

in some cases 

erythroblasts occur in sheets and constitute 

>80% of the cells in the bone marrow biopsy 

GENETICS 

● t(8;16)(p11.2;p13.3) can be associated with 

acute monocytic leukemia or acute 

myelomonocytic leukemia and in most cases is 

associated with hemophagocytosis (in 

particular erythrophagocytosis) by leukemic 

cells and with disseminated intravascular 

coagulation 

PURE ERYTHROID LEUKEMIA (DI GUGLIELMO DISEASE- 

M6) 

● Neoplastic proliferation of immature cells 

(undifferentiated or proerythroblastic in 

appearance) committed exclusively to the 

erythroid lineage (>80% of the bone marrow 

cells are erythroid, with ≥30% proerythroblasts) 


Figure 6 


● Positive: glycophorin (CD235a), hemoglobin A, 

E-cadherin and CD71 

● Blasts positive for KIT (CD117) and usually 

negative for HLA-DR and CD34 

● Negative: Antigens associated with 

megakaryocytes (i.e., CD41 and CD61) 

Figure 7 

Figure 5 

● Medium-sized to large erythroblasts with round 

nuclei, fine chromatin, and one or more nucleoli 

(proerythroblasts); deeply basophilic and 

agranular cytoplasm 

● Frequently contains vacuoles (PAS block positive) 

● Cells are negative for MPO and Sudan Black B; 

they show reactivity with alpha-naphthyl acetate 

esterase, acid phosphatase, and PAS (usually in a 

block-like PAS staining pattern) 

● In cases with hemodilution, the diagnosis of pure 

erythroid leukemia can be made if the neoplastic 


GENETICS 

● Complex karyotypes with multiple structural 

abnormalities 

● Loss of chromosome 5/del(5q) and loss of 

chromosome 7/del(7q) common (AML-MRC by 

definition though!) 

ACUTE MEGAKARYOBLASTIC LEUKEMIA (M7) 

● ≥20% blasts, of which ≥50% are of 

megakaryocyte lineage 


● Cytopenias (thrombocytopenia), although some 

may have thrombocytosis 


Figure 8 

Picture credit: Sara Javidiparsijani 

● Dysplastic features in the neutrophils, erythroid 

precursors, platelets, and megakaryocytes may 

be present, but the criteria for AML-MRC are not 

met 

● Megakaryoblasts: medium-sized to large blasts 

with a round, slightly irregular, or indented 

nucleus with fine reticular chromatin and 1-3 

nucleoli 

● Cytoplasm is basophilic, often agranular, and 

may show distinct blebs or pseudopod 

formation 

● Circulating micromegakaryocytes, 

megakaryoblast fragments, large dysplastic 

platelets, and hypogranular neutrophils may be 

present 

• Micromegakaryocytes should not be counted 

as blasts! 

• Dry tap due to extensive reticulin fibrosis 

• Bone marrow biopsy: uniform population of 

poorly differentiated blasts or mixture of poorly 

differentiated blasts and maturing dysplastic 

megakaryocytes 

● Differential diagnosis: Minimally differentiated 

AML, AML-MRC, acute panmyelosis with 

myelofibrosis, lymphoblastic leukemia, pure 

erythroid leukemia, blastic transformation of 

chronic myeloid leukemia, and the blast phase of 

any other myeloproliferative neoplasm 

● Some metastatic tumors in the bone marrow, in 

children (e.g., alveolar rhabdomyosarcoma), may 

mimic acute megakaryoblastic leukemia 


● Positive: CD41 (glycoprotein IIb/IIIa), CD61 

(glycoprotein Illa), and CD42b (glycoprotein lb) 

● Myeloid-associated markers CD13 and CD33 may 

be positive 

● Negative: CD34, CD45, and HLA-DR, MPO 

● Aberrant expression of CD7 seen 

● Cytoplasmic expression of CD41 or CD61 is more 

specific and sensitive than surface staining 

PROGNOSIS 

● Worse compared to other AML types (AML with 

t(1;22) and associated with Down syndrome) 

● In young males with mediastinal germ cell 

tumors and acute megakaryoblastic leukemia, 

isochromosome 12p is characteristic 

● Myelofibrosis can be present - bone marrow 

fibrosis - streaming, (no splenomegaly in acute 

panmyelosis) - use IHC and flow cytometry to 

distinguish the blasts 

ACUTE BASOPHILIC LEUKEMIA 

● Myeloblasts and metachromatic (purple-red on 

toludine blue) blasts ≥20% and basophils ≥40% 

of nucleated in BM/PB 



● Cutaneous involvement, organomegaly, lytic 

lesions, and symptoms related to 

hyperhistaminemia may be present 


● Blasts: medium-sized, with a high N:C ratio; oval, 

round, or irregular nucleus characterized by 

dispersed chromatin, and 1-3 prominent nucleoli 

● Cytoplasm is moderately basophilic and contains 

a variable number of coarse basophilic granules 

that are positive with metachromatic staining 

(toluidine blue stains granules pink) 

● Mature basophils are usually sparse 

● Lack of CAE reactivity, and cKIT can help 

distinguish blasts of acute basophilic leukemia 

from mast cells 

● Differential diagnosis: Blast phase of a 

myeloproliferative neoplasm; AML subtypes with 

basophilia, such as AML with t(6;9) (p23;q34.1); 

AML with BCR-ABL1; mast cell leukemia; and 

more rarely a subtype of lymphoblastic leukemia 

with prominent coarse granules 


● Positive: CD13 and CD33; CD123, CD203c, and 

CD11b 

● Negative for other monocytic markers and KIT 

(CD117) 

● Immunophenotypic detection of abnormal mast 

cells expressing KIT, mast cell tryptase, and CD25 

distinguishes mast cell leukemia from acute 

basophilic leukemia 

GENETICS: 

● t(X;6)(p11 .2;q23.3) in male infants with acute 

basophilic leukemia 

ACUTE PANMYELOSIS WITH MYELOFIBROSIS (APMF) 

● Acute panmyeloid proliferation with increased 

blasts (>20% of cells in the bone marrow or 

peripheral blood) and accompanying fibrosis of 

the bone marrow 


● Acutely sick, with severe constitutional 

symptoms including weakness and fatigue, fever 

and bone pain 

● Pancytopenia is always present 


● RBCs show no or minimal anisopoikilocytosis and 

variable macrocytosis; rare erythroblasts can be 

seen, but teardrop-shaped cells (dacryocytes) 

absent 

● Bone marrow aspirate is dry tap 

● Diffusely fibrotic stroma, increased erythroid 

precursors, increased granulocyte precursors, 

and increased megakaryocytes; i.e., there is 

panmyelosis 

● Foci of blasts associated with conspicuously 

dysplastic megakaryocytes predominantly of 

small size with eosinophilic cytoplasm showing 

variable degrees of cytological atypia, including 

the presence of hyposegmented or non-lobated 

nuclei with dispersed chromatin 


● Other types of AML with associated bone 

marrow fibrosis, including acute 

megakaryoblastic leukemia 

● If the proliferative process is predominantly of 

one cell type (i.e., myeloblasts) and there is 

associated myelofibrosis, the case should be 

classified as AML with a specific subtype (e.g., 

myelodysplasia-related) and designated with the 

qualifying phrase 'with myelofibrosis' 

● Acute megakaryoblastic leukemia is associated 

with the presence of ≥20% blasts, of which ≥50% 

are megakaryoblasts. Usually, they do not 

express CD34. Blasts of APMF are myeloid and 

poorly differentiated, express CD34, do not 

express megakaryocytic markers, and are 

associated with a panmyelotic proliferative 

process that involves all of the major bone 

marrow cell lines 

● BM biopsy supplemented by 

immunohistochemistry reveals more blasts in 


APMF than in MDS with excess blasts. Clinically, 

APMF can be distinguished from MDS by its 

more-abrupt onset with fever and bone pain 

● APMF is distinguished from primary 

myelofibrosis by its more numerous blast cells, 

and the megakaryocytes in primary myelofibrosis 

show distinctive cytological characteristics 

(highly atypical megakaryocytes, teardrop cells - 

PMF; lack of splenomegaly and fewer teardrop 

cells in panmyelosis) 


● Positive: progenitor early precursor marker 

CD34 and one or more myeloid associated 

antigens: CD13, C33, KIT (CD117) 

● MPO is usually negative in the blasts 

● Multilineage nature of the proliferation 

demonstrated by a panel of antibodies that 

includes MPO, lysozyme, megakaryocytic 

markers (e.g., CD61, CD42b, CD41, and von 

Willebrand factor), and erythroid markers (e.g., 

CD71, glycophorin, and hemoglobin A) 

PROGNOSIS 

● Poor response to chemotherapy and survival 

times of only a few months 


Table 1: Acute Myeloid Leukemia, Not Otherwise Specified 

Demographics and 

clinical presentation 

Morphology Immunophenotyping Genetics 

AML with minimal 


AML without 

maturation 

AML 

with 

maturation 

AML with 

myelomonocytic 


AML with 

monoblastic 

(M5a) and 

monocytic (M5b) 

maturation 

Primary erythroid 

leukemia 

Acute 


leukemia 

Acute basophilic 

leukemia 

Acute 

panmyelosis with 

pan fibrosis 

• Infants and elderly 


• Few may show 

leukocytosis 

• Elderly 


• Medium-sized blasts, no granules/auer 

rods 

• Basophilia 

• BM: hypercellular 

• MPO, SBB, CAE: negative (3% MPO+ 

• Monocytes, monoblasts, promonocytes: 

NSE + 

• Dual positive: NSE and CAE/MPO 

• M5a: ≥80% are monoblasts 

• M5b: predominantly promonocytes and 

monocytes 

• BM, extramedullary lesions: 

hypercellular with blasts 

• >80% BM cells are erythroid and ≥30% 

are proerythroblasts 

• PAS: block positivity 

• MPO, SBB: negative 

• ≥20% blasts with ≥50% of blasts are of 

megakaryocytic lineage 

• BM: fibrosis (dry tap) 

• Basophils >40% of nucleated cells in BM 

or PS 

• Blasts: cytoplasm contains coarse 

basophilic granules (metachromatic 

staining, toluidine blue positive) 

• BM: dry tap 

• Diffusely fibrotic with panmyelosis 

• Foci of blasts with dysplastic 


• Early markers: CD34, CD38, HLA-DR, TDT 

• Myeloid markers: CD13, CD33, CD117 

• CD7: aberrantly expressed 

• Negative: MPO, CD11b, CD15, CD14, CD65 

• MPO+ 

• One or more myeloid markers: CD13, CD33, CD117 

• CD34, HLA-DR positive 

• Lymphoid, mature monocytic and mature 

granulocytic markers are negative 

• Myeloid maturation markers are expressed: CD13, 

CD33, CD65, CD11b, CD15 

• Few cases: HLA-DR, CD34, CD117 

• CD7 aberrantly expressed 

• CD13, CD33, CD65, CD15 +ve 

• More than 1 monocytic marker expressed: NSE, 

CD14, CD4, CD11B, CD11C, CD64 (bright), CD68, 

CD36, Lysozyme 

• CD13, CD33, CD15, CD65 

• More than 1 monocytic marker expressed: 

• CD14, CD4, CD11b, CD11c, CD64 (bright), CD68, CD 

36, Lysozyme 

• HLA-DR positive 

• MPO: positive in some cases 

• Aberrant expression of CD7, CD56 

• Glycophorin, Hemoglobin A, E-cadherin: positive 

• CD71, CD117, CD34, HLA-DR are positive 

• CD41, CD61, CD42b 

• CD13, CD33 may be positive 

• CD7 is aberrantly expressed 

• negative: CD34, CD45, MPO, HLA-DR 

• CD13, CD33, CD123, CD203c, CD11b expressed 

• Negative for CD117 

• Blasts are poorly differentiated, express CD34 

• One or more myeloid marker expressed: CD13, 

CD33, CD117 

• MPO is usually negative in blasts 

• Multilineage proliferation indicated by 

• MPO/lysozyme 

• CD61/CD41/CD42b 

• CD71/Glycophorin/hemoglobin A 


• Unbalanced 


• Del 5q/7q/11q (AML-MRC) 


• t(8;16) associated with 

hemophagocytosis and 

DIC 


• del 5q 

• del 7q (AML-MRC) 

• iso12p in young males 

with associated 

mediastinal germ cell 

tumor 

• t(X;6) (p11.2, q23.3) 

Table credits: Kshitija Kale 


Chapter 8.5: Myeloid Sarcoma (MS) 


INTRODUCTION 

● Tumor mass consisting of myeloid blasts, with 

or without maturation, occurring at an 

anatomical site other than the bone marrow 

● Infiltration of any site of the body by myeloid 

blasts in a patient with leukemia is not classified 

as myeloid sarcoma unless it presents with 

tumor masses in which the tissue architecture is 

effaced. (Effacement is the keyword here!) 

Demographics 

● Males affected more commonly 



● Can involve any site in the body; the most 

frequently affected are the skin, lymph nodes, 

gastrointestinal tract, bone, soft tissue, and 

testes 


● Can occur in the absence of an underlying AML 

or other myeloid neoplasms in some cases 

● Its detection should be considered the 

equivalent of a diagnosis of AML 

● It may precede or coincide with AML or 

constitute acute blastic transformation of 

MDS, myelodysplastic/myeloproliferative 

neoplasms (MDS/MPN), or MPN 

● Can be initial manifestation of relapse in a 

previously diagnosed AML 

● Also seen in patients who have undergone 

allogeneic stem cell transplantation 

● Can also be associated with non-Hodgkin 

lymphoma or with a previous history of nonhematopoietic 

tumor 


● Most commonly consists of myeloblasts with or 

without features of promyelocytic or 

neutrophilic maturation. It can also show 

myelomonocytic or pure monoblastic 

morphology 

● Tumors predominantly composed of erythroid 

precursors or megakaryoblasts are rare 

Lymph Node 

● Infiltrates the paracortex surrounding reactive 

follicles or grows diffusely, often extending into 

the perinodal fat 

Extranodal Sites (Fig 1: Vaginal MS) 

● Neoplastic cells frequently mimic metastatic 

carcinoma by forming cohesive nests and/or 

single files surrounded by fibrotic septa 

Cytochemistry 

● Granulocytic-lineage forms: MPO and CAE 

● Monoblastic forms: Non-specific esterase 


Figure 2 

Figure 1 


● Tumors with a more immature myeloid profile 

express CD33, CD34, CD68 (KP1 but not PGM1), 

and KIT (CD117) 

● Promyelocytic cases lack CD34 and TdT but 

express MPO and CD15 

● Myelomonocytic tumors are positive for 

CD68/KP1, with MPO and CD68/PGM1 (or 

CD163) 

● Monoblastic variant expresses CD68/PGM1 

● Rare erythroid cases show strong positivity for 

glycophorin A and C, as well as hemoglobin and 

CD71 

● Megakaryoblastic myeloid sarcoma expresses 

CD61, LAT, and von Willebrand factor 

● Few myeloid sarcomas show variable degrees of 

CD56 and CD99 expression 

● Foci of plasmacytoid dendritic cell 

differentiation (CD123+, CD303+, but CD56-) 

are seen in cases with inv(16) 

● Rarely, aberrant antigenic expressions 

(cytokeratins, B-cell or T-cell markers, or CD30) 

are observed 

leukemia/lymphoma, Burkitt lymphoma, 

diffuse large B-cell lymphoma, small round cell 

tumors (in particular in children), and blastic 

plasmacytoid dendritic cell neoplasm 

● Non-effacing extramedullary blastic 

proliferations, which can occur in AML or in 

conjunction with acute transformation of MPN, 

MDS, or MDS/MPN 

● Extramedullary hematopoiesis (e.g., following 

the administration of growth factors that can 

produce pseudo-tumoral masses) 


Prognosis 

● Allogeneic or autologous bone marrow 

transplantation has a higher probability of 

prolonged survival or cure 

● Clinical behavior and response to therapy are 

not influenced by age, sex, anatomical site(s) 

involved, type of presentation (previous history 

of myeloid neoplasm, therapy, histology, 

immunophenotype, or cytogenetics 

GENETICS 

● Most cases show monosomy 7; trisomy 8; 

KMT2A rearrangement; inv(16); trisomy 4; 

monosomy 16; loss of 16q, 5q, or 20q; and 

trisomy 11 

● Few cases carry NPM1 mutations as well 

● t(8;21)(q22;q22) is observed in pediatric series 

● inv(16) or amplification of CBFB (breast, uterus, 

or intestinal involvement and possible foci of 

plasmacytoid dendritic cell differentiation) 

● Trisomy 8 and KMT2A-MLLT3 (higher incidence 

in myeloid sarcoma involving the skin or breast) 


● The major differential diagnosis is malignant 

lymphoma. The diagnosis of myeloid sarcoma is 

confirmed by cytochemical and/or 

immunophenotypic analyses 

● This allows the distinction of myeloid sarcoma 

from B- and T-lymphoblastic 


Chapter 8.6: Myeloid proliferations associated with Down 

Syndrome 


TRANSIENT ABNORMAL MYELOPOIESIS ASSOCIATED 

WITH DOWN SYNDROME 

INTRODUCTION 

● Unique disorder of newborns with Down 

syndrome that presents with clinical and 

morphological findings indistinguishable from 

those of acute myeloid leukemia 

● Blasts have morphological and immunological 

features of megakaryocytic lineage 

Demographics 

● TAM is diagnosed in approximately 10% of 

newborns with Down syndrome, but the true 

incidence may be higher 

● Extremely rare in neonates without 

chromosome 21 abnormalities 


● Peripheral blood and bone marrow 


● Usually diagnosed at the age of 3-7 days, but 

some patients are asymptomatic and diagnosed 

later 

● Thrombocytopenia is the most common 

presentation 

● Hepatosplenomegaly (tough to assess in a 

newborn). Hepatic dysfunction associated with 

poor outcome 

● Less common clinical features include jaundice, 

ascites, respiratory distress, bleeding, and 

pericardial or pleural effusions 

● In most cases, there is spontaneous remission 

within the first three months of life; a few 

children experience life-threatening 

complications 


● Leukocytosis, thrombocytopenia 

● Peripheral blood blasts outnumber marrow 

● Blasts: megakaryoblasts with basophilic 

cytoplasm with coarse basophilic granules and 

cytoplasmic blebbing suggestive of 

megakaryoblasts 

● Some patients have peripheral blood basophilia; 

erythroid and megakaryocytic dysplasia is often 

present in the bone marrow 


● CD41, CD42b, and CD61 for blasts of 

megakaryocytic lineage 

● Also positive for CD45, CD34 (most cases), KIT 

(CD117), CD13, CD33, HLA-DR, CD4 (dim), 

CD110 (TPOR), IL3R (CD123), CD36, and CD71 

● Aberrant expression of CD7 and CD56 seen 

GENETICS 

● GATA1 mutation (not a driver mutation, just 

accelerates megakaryopoiesis) 

● Other mutations acquired in cases that progress 

to AML 


Prognosis 

● Although there is a high rate of spontaneous 

remission, non-transient acute myeloid 

leukemia develops 1-3 years later in 20-30% of 

cases 

Treatment 

● Indications for chemotherapy in TAM are not 

firmly established 

MYELOID LEUKEMIA ASSOCIATED WITH DOWN 

SYNDROME 

INTRODUCTION 

● Unique to children with Down syndrome 

● The term 'myeloid leukemia associated with 

Down syndrome' includes both MDS and AML, 

but most common are AML with 

megakaryocytic differentiation 

● Acute megakaryoblastic leukemia constitutes a 

large portion of all cases of acute leukemia in 

Down syndrome, beyond the neonatal period 

Demographics 


● Most children are 5 years age, the risk of AML is equal 

irrespective of the presence of Down syndrome 


● Blood and bone marrow are the principal sites 

of involvement 

● Extramedullary involvement, mainly of the 

spleen and liver, is almost always present 


● Clinical course in children with

● Blasts are positive for CD117, CD13, CD33, 

CD11b, CD7, CD4, CD42, CD110 (TPOR), IL3R 

(CD123), CD36, CD41, CD61, and CD71, and 

negative for MPO, CD15, and glycophorin A 

● Unlike in TAM, CD34 is negative in 50% of 

cases, and some cases are negative for CD56 

and CD41 

● Antibodies to CD41, CD42b, and CD61 may be 

useful for identifying cells of megakaryocytic 

lineage 

GENETICS 

● Somatic mutations of the gene encoding the 

transcription factor GATA1 are considered 

pathognomonic of TAM associated with Down 

syndrome or MDS/AML associated with Down 

syndrome 

● Children aged >5 years with myeloid leukemia 

may not have GATA1 mutations, and such cases 

should be considered conventional MDS or 

AML 

● Trisomy 8 is a common cytogenetic abnormality 


Prognosis 

● Myeloid leukemia in older children with Down 

syndrome with GATA1 mutation and 

monosomy 7 has a poorer prognosis, 

comparable to that of AML in patients without 

Down syndrome 

Treatment 

● Children

Chapter 9: Acute Leukemia 

of Ambiguous Lineage 


Chapter 9.0: Acute Leukemia of Ambiguous lineage 

Nupur Sharma 



Chapter 9.0: Acute Leukemia of Ambiguous lineage 

INTRODUCTION 

● No clear evidence of differentiation into any 

lineage 

Includes: 

‣ Acute undifferentiated leukemia 

‣ Mixed phenotype acute leukemia (MPAL) 

● Acute bilineage (two separate population of 

blasts of more than one lineage) and 

biphenotypic (single population of blasts coexpress 

antigens of more than one lineage) are 

now reclassified as MPAL 

● Requirements for assigning more than one 

lineage to a single blast population: 

Myeloid lineage 

MPO (by flow cytometry, 

immunohistochemistry, or cytochemistry) 

or 

Monocytic differentiation (≥2 of the 

following: non-specific esterase, CD11c, 

CD14, CD64, lysozyme) 

T-cell lineage 

Cytoplasmic CD3 (by flow cytometry with 

antibodies to CD3 epsilon chain. 

Immunohistochemistry using polyclonal 

anti-CD3 antibody may detect CD3 zeta 

chain, which is not T-cell-specific) 

or 

Surface CD3 (rare in mixed-phenotype 

acute leukemias) 

B-cell lineage 

Strong CD19 with ≥1 of the following 

strongly expressed: CD79a, cytoplasmic 

CD22, CD10 

or 

Weak CD19 with ≥2 of the following 

strongly expressed: CD79a, cytoplasmic 

CD22, CD10 

Reprinted with permission from WHO Classification of 

Tumors, Revised 4th Edition, Vol 2, Page 181; Borowitz et 

al.; Acute leukemia of ambiguous lineage, 2017 

Nupur Sharma 


ACUTE UNDIFFERENTIATED LEUKEMIA (AUL) 

● Perform immunophenotyping with a 

comprehensive panel of monoclonal antibodies 

and exclude leukemias of unusual lineages like 

basophilic or dendritic cell lineages before 

making this diagnosis 

Demographics 

● Extremely rare, frequency unknown 


● Blood and bone marrow 


● Blasts are small to medium with a round to oval 

nuclei, conspicuous nucleoli, and scant 

cytoplasm 

● Lack of myeloid-specific Auer rods or 

cytoplasmic granules 


● Positive: Blasts express HLA-DR, CD34, and/or 

CD38 and may be positive for TdT 

● Negative: Lack the T-cell marker cCD3 and 

myeloid markers MPO and do not express B-cell 

markers such as cCD22, cCD79a, or strong CD19 

and lack monocytic markers: NSE, CD14, CD64, 

Lysozyme, CD11C 

● Weak CD7 expression 

GENETICS 

● Genes associated with poor prognosis in acute 

myeloid leukemia (such as BAALC, ERG, and 

MN1) are often expressed 


● AML (M0) is a challenging differential as it is 

minimally differentiated, and both respond 

poorly to chemotherapy 

● In such cases, CD117/CD13/CD33 positivity 

confirms myeloid lineage and should exclude 

AUL 

● AUL when associated with complex karyotype, 

shows features of AML-MRC and diagnosis of 

AML-MRC is preferred over AUL 


MIXED-PHENOTYPE ACUTE LEUKEMIA WITH 

t(9;22)(q34.1;q11.2); BCR-ABL1 

● Fulfills the criteria for MPAL and has blasts with 

t(9;22) and/or BCR-ABL1 rearrangement 

Demographics 

● More common in adults, rare leukemia 


● Blasts: dimorphic blast population, with some 

blasts resembling lymphoblasts and others 

myeloblasts, although other cases have no 

distinguishing features 

● Distinguish from blast phase of CML 


● Majority of cases have blasts that meet the 

criteria for B-cell and myeloid lineage as 

described above, although some cases have T- 

cell and myeloid blasts 

GENETICS 

● All cases have either t(9;22) detected by 

conventional karyotyping or the BCR-ABL1 

translocation detected by FISH or PCR 

● p190 fusion transcript is more common than 

the p210 transcript 

● If the p210 transcript is present, CML in a 

mixed blast crisis should be considered, 

especially if there are two distinct lymphoid and 

myeloid blast populations 

PROGNOSIS 

● Poor prognosis, worse than that of other MPALs 

MIXED-PHENOTYPE ACUTE LEUKEMIA WITH 

t(v;11q23.3); KMT2A-REARRANGED 

● Fulfills criteria for MPAL and has blasts with a 

translocation involving KMT2A (previously 

called MLL) 

Demographics 

● More common in children, especially infants 


● Dimorphic blast population, with some blasts 

clearly resembling monoblasts and others 

resembling lymphoblasts 

● Some cases have no distinguishing features and 

appear only as undifferentiated blast cells 

● Cases with an entire blast population that 

appear monoblastic are more likely AML with 

KMT2A translocation, but flow cytometry 

should be done to exclude the presence of a 

small lymphoblastic population 


● Lymphoblast population: CD19+, CD10-, pro-B 

(B-cell precursor, B-1) immunophenotype are 

frequently positive for CD15 

● Cases also fulfill the criteria for myeloid lineage 

most commonly via demonstration of a 

separate population of myeloid (usually 

monoblastic) leukemic cells 

GENETICS 

● All cases have rearrangements of KMT2A, with 

the most common partner gene being AFF1 

(AF4) on chromosome 4 

● t(9;11) and t(11;19) have also been reported 


MIXED-PHENOTYPE ACUTE LEUKEMIA, B/MYELOID, 

NOT OTHERWISE SPECIFIED 

● Fulfills the criteria for B/myeloid leukemia as 

described above, but does not fulfill the criteria 

for any of the genetically defined subgroups 


● Most cases either have blasts with no 

distinguishing features - morphologically 

resembling lymphoblastic leukemia (ALL) - or 

have a dimorphic population with some blasts 

resembling lymphoblasts and others 

myeloblasts 


● B/Myeloid 


● MPO+ myeloblasts and monoblasts commonly 

also express other myeloid associated markers, 

including CD13, CD33, and KIT (CD117) 

● CD20+ B-cells are rare and seen when B-cell 

lineage blasts are present 

● Blasts meet the criteria for both T-cell and 

myeloid lineage 

● MPO+ myeloblasts and monoblasts commonly, 

also express other myeloid associated markers, 

CD13, CD33, and KIT (CD117) are positive 

● T-cell component expresses T-cell markers, 

including cCD3, CD7, CD5, and CD2 

Figure 1 

GENETICS 

● del(6p), 12p11.2 abnormalities, del (5q), 

structural abnormalities of chromosome 7, and 

numerical abnormalities like near tetraploidy, 

complex karyotypes are common 

● Gene expression molecular signature between 

AML and ALL 

PROGNOSIS 

● Poor, especially with unfavorable genetics 

MIXED-PHENOTYPE ACUTE LEUKEMIA, T/MYELOID, 

NOT OTHERWISE SPECIFIED 

● Fulfills the criteria for both T-cell and myeloid 

lineage 


● Most cases either have blasts with no 

distinguishing features (morphologically 

resembling lymphoblastic leukemia) or can 

have a dimorphic population with some blasts 

resembling lymphoblasts and others 

myeloblasts 


Figure 2 

PROGNOSIS 

● Prognosis poor, no specific genetic anomalies 

MIXED-PHENOTYPE ACUTE LEUKEMIA, NOT 

OTHERWISE SPECIFIED, RARE TYPES 

● Blasts show clear-cut evidence of both T-cell 

and B-cell lineage commitment. Too few cases 

to characterize 

ACUTE LEUKEMIAS OF AMBIGUOUS LINEAGE, NOT 

OTHERWISE SPECIFIED 

● Express combinations of markers that do not 

classify them as either acute undifferentiated 

leukemia or mixed phenotype acute leukemia 

● No unique immunophenotype 

● Include cases that express T-cell associated 

markers such as CD7 and CD5, but lack more 

specific markers such as cCD3, along with 

myeloid-associated antigens such as CD33 and 

CD13 without MPO 




Chapter 10: Blastic 

Plasmacytoid Dendritic 

Cell Neoplasm 


Chapter 10.0: Blastic Plasmacytoid Dendritic Cell Neoplasm 

Nupur Sharma 



Chapter 10.0: Blastic Plasmacytoid Dendritic Cell Neoplasm 

INTRODUCTION 

● Clinically aggressive tumor derived from the 

precursors of plasmacytoid dendritic cells 

(PDCs, also called professional type I interferon 

producing cells or plasmacytoid monocytes) 

● High frequency of cutaneous and bone marrow 

involvement and leukemic dissemination 

● Possible association with MDS 

Demographics 

● Most patients are elderly but can be seen in 

children 


● Skin, PB, BM, lymph node 


● Diagnosis made on skin biopsy 

● Patterns: 

‣ Isolated (one or few) purplish nodule 

type 

‣ Isolated (one or few) bruise-like papule 

type, and 

‣ Disseminated type with purplish nodules 

and/or papules and/or macules 

● Isolated nodules common on the head and 

lower limbs and can be >10 cm in diameter 

● In absence of skin manifestations, blood and 

BM findings are useful for diagnosis, along with 

oral mucosal infiltration, regional adenopathy, 

cytopenias 

● Relapse is common, involving skin alone or skin 

and other sites, including soft tissue and CNS 

● Few cases of BPDCN are associated with or 

develop into other myeloid neoplasms, most 

commonly CMML, but also MDS or AML 

● IMPORTANT to distinguish from mature 

plasmacytoid dendritic cell proliferation 

(MPDCP), in which PDCs are morphologically 

mature and CD56-negative 

● MPDCP is associated with a myeloid disorder 

(most commonly CMML, MDS, or AML) 

Nupur Sharma 



Skin 

● Diffuse, monomorphous infiltrate of mediumsized 

blast cells resembling either lymphoblasts 

or myeloblasts 

● Nuclei have irregular contours, fine chromatin, 

and one to several small nucleoli 

● Cytoplasm is usually scant and appears greyish 

blue and agranular on Giemsa staining 

● Mitoses are variable in number, angioinvasion 

and coagulative necrosis are absent 

● Dermis is usually massively involved, with 

extension to the subcutaneous fat; epidermis 

and adnexa are spared 

Figure 1 

Figure 2 


Figure 3 Figure 4 

FNA, neck mass. Picture credits: Sara Javidiparsijani 

Lymph Node 

● Diffusely involved in the interfollicular areas 

and medulla, whereas B-cell follicles are often 

spared. 

Bone Marrow 

● Shows either a mild interstitial infiltrate 

(detectable only by immunophenotyping) or 

massive replacement; residual hematopoietic 

tissue may exhibit dysplastic features, especially 

in megakaryocytes 


● Positive: CD4, CD43, CD45RA, and CD56, as well 

as the PDC associated antigens CD123 (IL3 alpha 

chain receptor), CD303, TCL1A, CD2AP, and SPIB 

and the type I interferon- dependent molecule 

MX1 

● TCF4 is positive in most cases 

● Negative: CD3, CD13, CD16, CD19, CD20, LAT, 

lysozyme, and MPO are negative 

● BPDCNs also express antigens that are usually 

negative in normal PDCs, such as BCL6, IRF4, and 

BCL2 

● Pediatric cases: S100 

Flow cytometry 

● High levels of CD123 and weak expression of 

CD45 (blast gate); also, CD36, CD304, and LILRB4 

(also called ILT3) are expressed 

● Absence of lineage associated antigens, 

together with positivity for CD4, CD45RA, CD56, 

and CD123, is considered diagnostic 

(Mnemonic: 123456) 

● CD303 positivity has the highest diagnostic 

score within a panel of markers used for BPDCN 

identification 


Figure 5 

PROGNOSIS 

● Clinical course is aggressive with a short median 

survival 

● Age has an adverse impact on prognosis 

● High marrow or peripheral blood blast count, low 

TdT expression, positivity for CD303, low Ki67 

proliferation index, CDKN2A/B deletions and 

mutations in DNA methylation pathway genes 

associated with shorter survival 

Picture credits: Sara Javidiparsijani 

GENETICS 

● T-cell and B-cell receptor gene mutations are 

usually germline 

● Complex karyotypes are common; six major 

recurrent chromosomal abnormalities are seen, 

involving 5q21 or 5q34, 12p13, 13q13-21, 6q23- 

qter, 15q, and loss of chromosome 9 

● Deletion of CDKN2A, chromosome 4,9 & 13 

● TET2 commonly mutated 

● Recurrent somatic mutations in ASXL1, the RAS 

family of genes, and the newly identified genes 

IKZF3 and ZEB2 



Chapter 11: 

Myeloproliferative 

Neoplasms 


Chapter 11.1: Chronic Myeloid Leukemia, BCR-ABL1 

Positive 

Vanya Jaitly Nupur Sharma Akanksha Gupta 


Chapter 11.1: Chronic Myeloid Leukemia, BCR-ABL1 

Positive 

Vanya Jaitly Nupur Sharma Akanksha Gupta 

INTRODUCTION 

● Hematopoietic stem cell neoplasm defined by the 

presence of BCR-ABL1 fusion gene and 

proliferation of maturing granulocytic elements 

● Natural: Initial indolent chronic phase followed by 

accelerated phase, blast phase or both 

Demographics 

● Elderly; Males > Females 


● Blood, bone marrow, spleen, and liver 


● Usually asymptomatic; discovered incidentally 

● Splenomegaly, anemia, fatigue, weight loss 

● Subset of cases present with accelerated or 

blast phase 


Peripheral Smear and Bone Marrow 

Table 1: WHO CRITERIA - Diagnostic criteria for accelerated 

phase of chronic myeloid leukemia 

CML-AP is defined by the presence of ≥1 of the following 

hematological/cytogenetic criteria or provisional criteria 

concerning response to tyrosine kinase inhibitor (TKI) therapy 

Hematological/cytogenetic criteria a 

- Persistent or increasing high WBC count (>10 x 10 9 /L), 

unresponsive to therapy 

- Persistent or increasing splenomegaly, unresponsive to 

therapy 

- Persistent thrombocytosis (>1000 x 10 9 /L), unresponsive to 

therapy 

- Persistent thrombocytopenia (


● Flow cytometry is the modality of choice for 

immunophenotyping 

● In chronic phase aberrant expression of CD7 on 

CD34 positive blasts is associated with poor 

response to tyrosine kinase inhibitor (TKI) 

therapy 

● Blast phase 

‣ 2/3 rd of cases are of myeloid lineage 

(expression of antigens associated with 

granulocytic, erythroid, monocytic or 

megakaryocytic lineage) 

‣ 1/3 rd cases of lymphoid lineage (B 

lymphoblastic > T lymphoblastic > NK cell) 

and express associated antigens 

‣ Bilineage cases are also seen (two 

populations of blasts with expression of 

myeloid and lymphoid markers) 

GENETICS 

● Presence of BCR-ABL1 fusion gene formed as a 

result of t(9;22) (q34.1;q11.2) is the hallmark 

of this disease and is easily detected on 

karyotyping 

● Few cases have variant or cryptic translocations 

which are detectable by FISH or RT-PCR 

● Encoded oncoprotein results in constitutively 

active tyrosine kinase 

● Molecular testing should be performed at 

diagnosis to assess response to therapy and to 

detect mutations leading to resistance 

● Different breakpoint regions in BCR give rise to 

different oncoprotein isoforms 

‣ p210 (exons 12-16): CML 

‣ p190 (exons 1-2): Ph positive ALL, absolute 

monocytosis in CML, MPAL with BCR/ABL 

‣ p230 (exons 17-20): Prominent 

thrombocytosis and neutrophilic maturation 

● Additional abnormalities including extra Ph 

chromosome, isochromosome 17q, +8, +19, 

complex karyotype occur with progression to 

accelerated phase/blast phase 


Prognosis 

● Complete hematological, complete cytogenetic, 

major molecular (BCR-ABL

Chapter 11.2 Chronic Neutrophilic Leukemia 


WHO CRITERIA 

Diagnostic criteria for Chronic Neutrophilic Leukemia 

● Peripheral white blood cell count ≥25 X 10 9 /L 

‣ Segmented neutrophils plus banded neutrophils 

constitute ≥80% of the white blood cells 

‣ Neutrophil precursors (promyelocytes, myelocytes 

and metamyelocytes) constitute

● Increased M:E ratio 

● No significant dysplasia 

● Exclude plasma cell neoplasm 

Spleen 

● Neutrophilic infiltration of the red pulp 

Liver 

● Neutrophilic infiltration of the sinusoids and/or 

portal tracts 

● Cytochemistry 

● Elevated neutrophil alkaline phosphatase score 

GENETICS 

● Normal karyotype in 90% of cases 

● Association with CSF3R mutation, often together 

with SETBP1 or ASXL1, and with JAK2 V617F 


● Variable 

● Progressive condition followed by anemia and 

thrombocytopenia 

● Development of MDS is suggestive of 

transformation to AML 


Polcythemic Phase 

Spent Phase 

Chapter 11.3: Polycythemia Vera 


INTRODUCTION 

Table 1: Diagnostic Criteria for PV 

All three major criteria or the first two major criteria + 

the minor criterion: 

Major 

• Hb >16.5 g/dl in men, >16.0 g/dl in women 

or Hematocrit >49% in men, >48% in women 

or Increased (>25% above mean predicted 

value) red blood cell mass 

• BM is hypercellular with panmyelosis 

(prominent erythroid, granulocytic, and 

megakaryocytic proliferation with pleomorphic 

mature megakaryocytes) 

• Mutation in JAK2 V617F or JAK2 exon 12 

Minor 

• Subnormal serum erythropoietin level 

BM criteria not required if Hb >18.5 g/dl in males or 

>16.5 g/dl in females or Hct >55.5% in males or >49.5% 

in females. 

In a few cases, myelofibrosis is noted during the initial 

diagnosis itself. It is suggestive of a rapid progression to 

post-PV myelofibrosis 


Edition, Vol 2, Page 39 Thiele J et al. Chronic neutrophilic leukemia, 2017 

Table 2: Diagnostic Criteria for post PV myelofibrosis 

Required 

1. A prior diagnosis of PV 

2. Bone marrow fibrosis of higher grade 

Additional (2 required) 

• Anemia sustained or cessation of the need for 

phlebotomy or any therapy to reduce 

erythrocytosis 

• Leukoerythroblastosis 

• Splenomegaly: newly diagnosed or >5 cm 

increase from baseline 

• Any 2 or 3 of the following: unexplained fever, 

>10% weight loss in 6 months, night sweats 



Phases of PV 

Increased Hb level 

Increased Hematocrit 

Increased RBC mass 

Cytopenia 

BM fibrosis 

Extramedullary 

hematopoiesis 

Hypersplenism 

Masked PV 

● Obsolete term 

● For individuals with persistently raised Hb 

(>16.5g/dl in male, >16.0 g/dl female) AND with 

JAK2 mutations, BUT NO clinical manifestations 

● Thus, this is referred to as the latent phase 

Demographics 

● Adults, median age at diagnosis is 60 years 

● Slight male preponderance 


● Hypertension, stroke, mesenteric, portal, or 

splenic vein thrombosis (Budd- Chiari syndrome), 

headache, dizziness, visual disturbances, and 

paresthesia are major symptoms 

● Pruritus, erythromelalgia, and gout are also 

common 

MORPHOLOGY AND PHENOTYPE: Figure 1, 2 / Table 3 

Figure 1 


Figure 2: Polycythemia phase 

MORPHOLOGY AND PHENOTYPE: Table 3 

Table 3: Microscopic findings in PV 

Polycythemia Phase (Figure 1, 2) Spent phase and Post-PV 

myelofibrosis 

Peripheral 

Blood 

Bone Marrow Peripheral 

Blood 

Bone 

Marrow 

Panmyelosis Hypercellular Leukoerythroblastosis 

Normochromic 

and 

normocytic 

RBCs 

Neutrophilia 

Extensive sheets 

of erythroid 

precursors, 

however no 

atypia in 

erythroid cells 

Poikilocytosis 

(teardrop 

cells due to 

marrow 

fibrosis) 

Prominent 

fibrosis in 

the 

marrow 

GENETICS 

● Somatic gain-of-function mutations in JAK2 

V617F in most cases 

● Rare cases have acquired BCR-ABL1 

rearrangement. Clinical significance uncertain 

● JAK2 Exon 12 mutations: in 3% cases and show 

predominant erythroid hematopoiesis. 

● Recurrent abnormalities: 

‣ Gain of chromosome 8 or 9 

‣ del(20q) 

‣ del(13q) 

‣ del(9p) 

PROGNOSIS 

● Survival is adversely affected by leukocytosis and 

abnormal karyotype 

● Most common causes of death: thrombotic 

complications or secondary malignancies 

No evidence of 

blasts 

Megakaryocytes 

are increased in 

number with 

Hypersegmented 

nuclei and 

pleomorphism 

noted 

Dilated sinuses 

are filled with 

erythrocytes 

>10% blasts in blood or bone 

marrow or significant 

myelodysplasia indicates 

transformation to an accelerated 

phase 

≥20% blast suggestive of blast 

phase post-PV 

Persistent 

leukocytosis is 

suggestive of 

an aggressive 

course 

Also, hypersplenism. 

Splenic sinuses are packed 

with hematopoietic 

elements 


Chapter 11.4: Primary Myelofibrosis 


INTRODUCTION 

Table 1: Diagnostic criteria for pre-fibrotic stage of PMF 

Major criteria 

(all three required) 

1. Megakaryocytic proliferation and 

atypia, without reticulin fibrosis grade 

>1, accompanied by 

increased age-adjusted bone marrow 

cellularity, granulocytic proliferation, 

and (often) decreased 

erythropoiesis 

2. WHO criteria for BCR-ABL1— 

positive chronic myeloid leukemia, 

polycythemia vera, 

essential thrombocythemia, 

myelodysplastic syndromes, or other 

myeloid neoplasms are not met 

3. JAK2, CALR, or MPL mutation 

or 

Presence of another clonal marker like 

ASXL1 / EZH2/ TET2 / IDH1 / IDH2 / 

SRSF2 / SF3B1 

or 

Absence of minor reactive bone 

marrow reticulin fibrosis 

Minor Criteria 

(at least 1 on two 

consecutive 

determinations) 

1. Anemia 

2. Total leukocyte 

count ≥11 x 10 9 /L 

3. Splenomegaly 

(clinically palpable) 

4. Elevated LDH 



Table 2: Diagnostic criteria for overt fibrotic stage 


(all three required) 

1. Megakaryocytic proliferation and 

atypia, with reticulin and / or collagen 

fibrosis of grade 2 or 3 

2. WHO criteria for ET, PV, CML, MDS 

and other myeloid neoplasms are not 

met 

3. Presence of JAK2/CALR/MPL 

mutation or other mutations like 

ASXL1/EZH2/TET2/IDH1/IDH 

/SRSF2/SF3B1 or no evidence of 

minor marrow fibrosis due to any 

non-neoplastic etiology 

Minor Criteria 

(at least one on two 

consecutive 

determinations) 

1. Anemia 

2. Total leucocyte 

count ≥11 x 10 9 /L 

3. Splenomegaly 

(clinically palpable) 

4. Elevated LDH 

5. Leuko - 

erythroblastosis 


Edition, Vol 2, Page 45 Thiele J et al. Primary Myelofibrosis, 2017 

Demographics 

● Age: Elderly, male = females 

Sites of Involvement and clinical presentation 

● Most patient: splenomegaly 

● Approximately half of the patients: constitutional 

symptoms and/or hepatomegaly 

● Some patients can be asymptomatic 

● Also, hyperuricemia can be present leading to 

gouty arthritis, renal stones 


Bone Marrow microscopy (Figure 1,2; Table 3) 

Cellularity 

Atypical 


Table 3: Microscopic findings in BM 

Pre-Fibrotic stage Overt Fibrotic stage 

Hypercellularity Normocellular, 

Hypocellular > 

hypercellular 

Increased neutrophils, 


Occasional cases show 

lymphoid 

proliferations 

Dense, frankly atypical 

clusters seen around 

sinusoids and 

trabeculae 

Islands and patches 

of hematopoiesis 

noted 

Seen in clusters and 

large sheets 

Also seen within 

dilated sinuses 

Blasts Not increased Immature cells are 

seen, but 20% blasts: blast transformation 

● Extramedullary hematopoiesis seen in spleen and 

liver 


Figure 1 

GENETICS 

Table 3: Genetic mutations in PMF 

Most JAK2 Older age group, higher hematocrit 

common V617F 

2 nd most 

common 

CALR CALR positive: favorable outcome 

CALR negative, ASXL1 +: High risk 

CALR mutations in exon 9. Type 1 

mutations (deletions) are common and 

favorable than type 2 

(CALR gene alters protein CALRETICULIN 

which promotes activation of MPL) 

Some 

cases 

Some 

cases 

Very rare 

Some 

cases 

MPL More anemia and low WBC count 

(MPL encodes for Thrombopoietin 

Receptor) 

Triple A subset shows gain-of-function MPL, 

Negative S204P, MPL Y59N 

BCR- High propensity for CML-like evolution 

ABL1 

Show cytogenetic abnormalities: del 13q, der 6, del 

20q, partial trisomy 1q 

Table 2: Histological grading of BM fibrosis 

Grading of BM reticulin 

fibrosis 

MF 0 

MF 1 

MF 2 

MF 3 

Scattered 

reticulin fibers 

Loose reticulin 

network with 

intersections 

Dense reticulin 

network with 

extensive 

intersections 

Focal 

osteosclerosis 

Coarse thick 

collagen 

bundles 

Osteosclerosis 

++ 

Grading of collagen 

in BM 

0 Only 

perivascular 

collagen 

1 Focal paratrabecular 

collagen 

2 Focal collagen 

deposition with 

connecting 

meshwork 

3 Diffuse 

interconnecting 

collagen 

meshwork in > 

30 % BM 

Figure 2 

Grading of 

osteosclerosis 

0 Regular 

trabeculae 

1 Focal 

budding, 

hooks, 

spikes of 

new bone 

2 Thickening 

of 

trabeculae 

Diffuse new 

bone 

formation 

3 Extensive 

new bone 

replacing 

the marrow 

spaces 

PROGNOSIS 

Table 4: Dynamic International Prognostic Scoring System 

(DIPSS) 

Anemia (Hb 25 x 10 9 /L) 1 

Blasts in PS ≥1% 1 

Constitutional symptoms 1 

Age >65 years 1 

Unfavorable karyotype 1 

Platelet count

Treatment 

● Aim of treatment is to reduce the effects of 

anemia and splenomegaly 

● Blood transfusion, regular folic acid therapy 

● Erythropoietin can be tried, but worsens 

splenomegaly 

● JAK2 inhibitors - ruxolitinib: reduces spleen size, 

improves symptoms, reverses fibrosis 

● Hydroxycarbamide, allopurinol reduces 

hyperuricemia 

● Splenectomy: indicated in severe symptomatic 

splenomegaly 


Chapter 11.5: Essential Thrombocythemia 

Kshitija Kale 


INTRODUCTION 

Table 1: Diagnostic Criteria for ET 

Presence of all major OR 1-3 major and minor 


1. Platelet count ≥450 x 10 9 /L 

2. Bone marrow biopsy showing proliferation 

mainly of the megakaryocytic lineage, with 

increased numbers of enlarged, mature 

megakaryocytes with hyper lobulated nuclei; no 

significant increase or left shift in neutrophil 

granulopoiesis or erythropoiesis; very rarely a 

minor (grade 1) increase in reticulin fibers 

3. WHO criteria for BCR-ABL1-positive chronic 

myeloid leukemia, polycythemia vera, primary 

myelofibrosis, or other myeloid neoplasms are 

not met 

4. JAK2, CALR, or MPL mutation 

Minor criterion 

1. Presence of a clonal marker or 

2. Absence of evidence of reactive thrombocytosis 


4th Edition, Vol 2, Page 50 Thiele J et al. Essential Thrombocythemia, 2017 

Table 2: Diagnostic Criteria for post ET myelofibrosis 

Required criteria 

1. Documentation of a previous diagnosis of WHOdefined 

ET 

2. Bone marrow fibrosis of grade 2-3 on a 0-3 scale or 

grade 3-4 on a 0-4 scale 

Additional criteria (2 are required) 

1. Anemia (i.e., below the reference range given age, 

sex, and altitude considerations) and a >2 g/dL 

decrease from baseline hemoglobin concentration 

2. Leukoerythroblastosis 

3. Increasing splenomegaly, defined as either an 

increase in palpable splenomegaly of >5 cm from 

baseline (distance from the left costal margin) or 

the development of a newly palpable splenomegaly 

4. Elevated lactate dehydrogenase level (above the 

reference range) 

5. Development of any 2 (or all 3) of the following 

constitutional symptoms: >10% weight loss in 6 

months, night sweats, unexplained fever (>37.5 °C) 


4th Edition, Vol 2, Page 53 Thiele J et al. Essential Thrombocythemia, 2017 

Demographics 


● Elderly females are commonly affected with a 

second peak in younger females 

● Differential: hereditary thrombocytosis which 

harbors gelsolin gene (GSN) mutations 


● Most patients are asymptomatic 

● Thrombosis (both micro- and macrovascular), 

hemorrhage 

● Splenomegaly (few cases) 

● Note: Splenomegaly is mild and due to platelet 

sequestration and NOT due to extramedullary 

hematopoiesis 



● Marked thrombocytosis, platelet anisocytosis 

(ranging from tiny, atypical, large, or giant 

platelets), occasionally bizarre or with 

pseudopods or agranular forms 

● RBC, leukocyte count and the differential count is 

normal 

● Leukoerythroblastosis, teardrop RBCs are NOT 

seen in ET 

Bone Marrow microscopy 

Figure 1 

● Megakaryocytes – increased in number and size, 

“staghorn” (hypersegmented) nuclei 

● Few are mature and are typically dispersed 

(clusters are loose, if any) 

● Large sheets of platelets seen in BM aspirate 

● Emperipolesis, stainable iron positive 


Table 1: Caveats for marrow findings and diagnosis 

Associated finding 

Suspect 

Erythroid + granulocytic (Even if mild) + Prodromal 

megakaryocytic proliferation 

stage of PV 

Granulocytic proliferation + atypical Pre-PMF 

bizarre megakaryocytes 

Significant erythroid/granulocytic 

MDS 

dysplasia 

● Blasts/erythroid cells/granulocytic lineage are 

normal 

● Erythroid hyperplasia can be seen in recurrent 

hemorrhage or on hydroxycarbamide treatment 

● Fibrosis: absent or very mild (never > WHO grade 

1, seen in rare cases) 

● Significant fibrosis at presentation excludes the 

diagnosis of ET 

GENETICS 

● Mutations in JAK2 V617F are most common 

followed by CALR and rarely in MPL 

● Some cases may show gain of MPL S240P and 

MPL Y591N 

● Gain of chromosome 8, 9q, del 20q 

Erythroid 

lineage 

Granulocytic 

lineage 

Features 

● Very rarely acquired BCR-ABL1 may lead to a 

CML-like evolution in ET 


Prognosis and course 

● Indolent course, long symptom-free interval 

● Intermittent vascular events 

● Post-ET myelofibrosis with EMH in only a few 

cases 

● Note: crucial to distinguish ET v/s pre-PMF as 

prognosis is very different 

● Transformation to blast phase/ MDS is very rare, 

linked to prior cytotoxic therapy 

Treatment 

● If patients are asymptomatic and no 

cardiovascular risk factors or tobacco abuse, no 

treatment needed 

● Drugs which can be used to reduce platelet count 

include pegylated INF alpha, anagrelide, 

hydroxyurea 

● Role of ruxolitinib is yet to be established 

Comprehensive summary of Bone Marrow features of chronic myeloproliferative disorders 

PV – 

Polycythemic Phase 

PV – Spent 

Phase 

Essential 

Thrombocythemia 

Pre-PMF 

Overt-PMF 

Cellularity Raised Reduced Normal Raised Reduced 

M:E Ratio 

Erythropoiesis 

Panmyelosis: 

normal/reduced 

Raised 

left shift +++ 

- Normal Raised - 

Reduced Normal Normal Reduced 

Granulopoiesis 

Raised 

Raised Reduced Normal 

left shift + 

Reduced 

Megakaryopoiesis Raised Reduced Raised +++ Raised +++ Raised + 

Size Variable, pleomorphic - Large/Giant Variable Small megs + 

Megakaryocytic 

lineage 

Marrow fibrosis 

Stromal reaction 

Location - - - Endosteal Endosteal 

Arrangement of 


Loose clusters + - Loose clusters + Dense clusters + Dense clusters ++ 

Nuclear lobulations Hyperlobations - Hyperlobations Hypolobations Hypolobations 

Nuclear atypia None - None ++ +++ 

Naked nuclei None - + ++ +++ 

Fibrosis 

upto grade 1 + grade 2 – 3 +++ 

Reticulin fibrosis 

Not noted Noted Noted in < 5 % 

+ +++ 

Collagen fibrosis Not seen ++ 

Osteosclerosis Not seen ++ 

Iron Deposits 

Not seen 

+ + ++ 


Chapter 11.6: Chronic Eosinophilic Leukemia (CEL) 

INTRODUCTION 

● Clonal proliferation of eosinophilic precursors 

causing persistent eosinophilia in peripheral 

blood, bone marrow and tissue 

Hypereosinophila 

Figure 1 

with organ damage 

Idiopathic HES 

Absolute 

eosinophil 

count >1.5 x 

10 9 /L 

with clonality 

and increased 

blast count (yet 

‣ Gain of chr 8, 

‣ Loss of chr 7, iso 17q 

‣ Mutations in ASXL1, TET2, EZH2, DNMT3A, 

SF3B1, SRSF2 


Prognosis 

● Poor, acute transformation common 

● Factors suggestive of unfavorable prognosis: 

‣ Marked splenomegaly 

‣ Increased number of blasts 

‣ Cytogenetic abnormalities 

‣ Dysplastic features in other myeloid lineages 

Treatment 

● Imatinib, anti-interleukin-5 (mepolizumab), 

steroids 

Table 2: Common differentials of CEL and their diagnostic 

clues 

Conditions with 

eosinophilia 

Reactive eosinophilia 

Eosinophilia of 

PDGFRA/ PDGFRB 

Lymphocytic variant 

of HES 

CMML with 

eosinophilia 

Atypical CML with 

eosinophilia 

Idiopathic HES 

Eosinophilia 

secondary to systemic 

conditions 

Diagnostic clues 

History of drugs, clinical suspicion 

of infections 

Presence of mast cells 

Clonal T-cells with abnormal 

immunophenotype 

Absolute monocyte count is >1 x 

10 9 / L 

Dysplasia, neutrophil precursors 

are >10%, no evidence of 

monocytosis 

Diagnostic criteria that need to be 

fulfilled: 

AEC >1.5 x 10 9 /L for >6 months 

Evidence of organ dysfunction 

Rule out AML, MDS, MDS/MPN, 

SM 

Rule out aberrant T-cell clone 

Vasculitis, granuloma, Hodgkin 

lymphoma, lymphoblastic 

leukemia 



Chapter 12: 

Myelodysplastic 

Syndrome 


Chapter 12: Myelodysplastic Syndrome 



Chapter 12: Myelodysplastic Syndrome 


INTRODUCTION 

● Clonal hematopoietic stem cell diseases 

characterized by cytopenias (hemoglobin 

concentration

Figure 1: BM: Dysplastic megakaryocyte and hypogranular neutrophil 

Figure 2: BM: Hypogranular neutrophils 

Figure 1 

Figure 2 

Figure 3 

Figure 3: Partial hypogranularity in neutrophils in peripheral smear 

● Micromegakaryocytes: Megakaryocyte markers 

(e.g., CD42b and CD61) can facilitate 

identification of small megakaryocytes and 

micromegakaryocytes (apoptotic 

megakaryocytes may superficially mimic 

micromegakaryocytes in immunostained 

sections) 

● HYPOPLASTIC MDS VERSUS APLASTIC ANEMIA: 

Significant dysplasia (most often 

micromegakaryocytes), increased blasts 

identified by CD34 staining of bone marrow 

biopsy sections, and an abnormal karyotype 

(excluding trisomy 8) favors MDS 

● MDS WITH FIBROSIS VERSUS MYELOFIBROSIS: 

Unlike primary myelofibrosis, MDS-F is usually 

not associated with splenomegaly, leukoerythroblastosis 

or intrasinusoidal hematopoiesis 

and typically exhibits MDS-type megakaryocyte 

morphology (i.e., micromegakaryocytes), other 

dysplastic changes and often increased blasts as 

revealed by CD34 immunostaining 

Table 2: Causes of dysplasia other than MDS 

Drugs 

Nutritional/ Heredit Others 

toxic ary 

Isoniazid: Ring 

sideroblasts 

Cotrimoxazole, 

Tacrolimus, 

Mycophenolate: 

Hyposegmented 

neutrophils 

Mycophenolate: 

Erythroblastopenia 

Chemotherapeutic 

agents: Trilineage 

dysplasia 

GCSF therapy: Left 

shift, 

Hypergranularity, 

and 

Hyposegmentation 

Vit. 

B 12/Folate 

deficiency 

Copper 

deficiency 

Arsenic, Pb, 

Zn toxicity 

AD 

Pelger 

Huët 

from a 

mutatio 

n in LBR 

gene 

CDA: 

Isolated 

dyserythro 

poiesis 

Hypothyroidis 

m 

Autoimmune 

disorders 

PNH 

Bone marrow 

lymphomatous 

involvement 

Parvovirus: 

Erythroblastopenia 

with giant 

pronormoblasts 


● Abnormal myeloid maturation patterns include 

asynchrony of CD15 and CD16 on granulocytes; 

altered expression of CD13 in relation to CD11b 


or CD16; and aberrant expression of CD56 and/or 

CD7 on progenitors, granulocytes or monocytes 

● In erythroid cells, an increased coefficient of 

variation and decreased intensity of CD71 or 

CD36 expression 

● Flow cytometry: Aberrant findings in at least 

three tested features and at least two cell 

compartments 

GENETICS 

Table 3: MDS defining cytogenetic abnormalities 

Unbalanced 

Gain of chromosome 8 a 

Loss of chromosome 7 or del(7q) 

del(5q) 

del(20q) a 

Loss of Y chromosome a 

Isochromosome 17q or t(17p) 

Loss of chromosome 13 or del(13q) 

del(11q) 

del(12p) or t(12p) 

del(9q) 

idic(X)(q13) 

Balanced 

t(11;16)(q23.3;p13.3) 

t(3;21)(q26.2;q22.1) 

t(1;3)(p36.3;q21.2) 

t(2;11)(p21;q23.3) 

inv(3)(q21.3q26.2)/t(3;3)(q21.3;q26.2) 

t(6;9)(p23;q34.1) 

a 

As a sole cytogenetic abnormality in the absence of 

morphological criteria, gain of chromosome 8, del(20q) 

and loss of Y chromosome are not considered definitive 

evidence of MDS; in the setting of persistent cytopenia of 

undetermined origin, the other abnormalities shown in 

this table are considered presumptive evidence of MDS, 

even in the absence of definitive morphological features. 

● MDS with isolated del(5q), i.e., either with a 

del(5q) alone or with one additional abnormality 

other than the loss of chromosome 7 or del(7q), 

is a specific MDS subtype. It occurs more often in 

women and is characterized by megakaryocytes 

with non-lobated or hypolobated nuclei, 

macrocytic anemia, normal or increased platelet 

count, and has a favorable clinical course 

● Loss of 17p is associated with MDS or AML with 

pseudo Pelger-Huët anomaly, small vacuolated 

neutrophils, TP53 mutation, and an unfavorable 

clinical course; it is most common in therapyrelated 

MDS 

● Isolated del(20q) is associated with 

dysmegakaryopoiesis and thrombocytopenia 

● inv(3)(q21.3q26.2) or t(3;3)(q21.3;q26.2) is 

associated with abnormal megakaryocytes and 

may be associated with thrombocytosis 

● Commonly mutated genes in MDS encode 

proteins that control RNA splicing (SF3B1, SRSF2, 

U2AF1, and ZRSR2) 

● MDS associated somatic mutations alone are not 

considered diagnostic of MDS 


● The low-risk group: MDS with single lineage 

dysplasia, MDS with ring sideroblasts and single 

lineage dysplasia, and MDS with isolated del(5q) 

● The intermediate-risk group: MDS with 

multilineage dysplasia and MDS with ring 

sideroblasts and multilineage dysplasia 

● The high-risk group: MDS with excess blasts 

MDS WITH SINGLE LINEAGE DYSPLASIA 

INTRODUCTION 

● Unexplained cytopenia or bi-cytopenia, with 

≥10% dysplastic cells in one myeloid lineage 

● Definitions of cytopenia: Hemoglobin 

concentration


● RBCs usually normochromic and normocytic or 

normochromic and macrocytic 

● Circulating blasts

PROGNOSIS 

● Prolonged median survival compared to MDS 

with excess blasts 

MDS WITH EXCESS BLASTS 

● 5-19% myeloblasts in the bone marrow or 2-19% 

blasts in the peripheral blood (but

● Significance of erythroid predominance is 

uncertain 

● High-risk karyotype and the presence of TP53, 

RUNX1, or ASXL1 mutations are associated with 

poor prognosis in MDS-EB with erythroid 

predominance 

MYELODYSPLASTIC SYNDROME WITH EXCESS BLASTS 

AND FIBROSIS 

● MDS with a significant degree of reticulin 

fibrosis (grade 2 or 3 according to the WHO 

grading system) 

● Presence of fibrosis is an independent 

prognostic parameter in MDS 

● Presence of an excess of blasts in cases of MDS- 

EB-F can be confirmed by 

immunohistochemistry for CD34 

● Characteristic finding in MDS-F is an increased 

number of megakaryocytes with a high degree 

of dysplasia, including small forms and 

micromegakaryocytes 

● Differential diagnosis: acute panmyelosis with 

myelofibrosis, distinguished by its abrupt onset 

with fever and bone pain, as well as by its 

higher blast count 

MYELODYSPLASTIC SYNDROME WITH ISOLATED 

del(5q) 

● Anemia (with or without other cytopenias 

and/or thrombocytosis) and del(5q) either in 

isolation or with one other cytogenetic 

abnormality, other than monosomy 7 or del(7q) 

● Associated with thrombocytosis 

● Pancytopenia should lead to classification as 

MDS, unclassifiable 

Etiology 

● Loss of a tumor suppressor gene or genes in the 

minimally deleted region (5q33.1) 

● Haploinsufficiency of RPS14, which encodes a 

ribosomal structural protein 

● Haploinsufficiency of miR-145 and miR146a 

● Haploinsufficiency of CSNK1A 1 (encoding 

casein kinase 1A1) leading to WNT/beta-catenin 

pathway deregulation 


● BM is usually hypercellular or normocellular 

with erythroid hypoplasia 

● Megakaryocytes are increased in number and 

are normal to slightly decreased in size, with 

conspicuously non-lobated and hypolobated 

nuclei 

● Blast percentage is

● Myeloblasts account for

● Somatic mutations altering genes of RAS 

pathway, transcription factors, and epigenetic 

modifiers 

● Children with MDS-EB may have a stable course 

REFRACTORY CYTOPENIA OF CHILDHOOD 

● Provisional MDS entity characterized by 

persistent cytopenia, with

Table 4: Diagnostic criteria for MDS categories 

Entity 

Number of 

dysplastic 

lineages 

Number of 

cytopenias a 

Ring sideroblasts 

as a percentage of 

marrow erythroid 

elements 

Bone marrow and 

peripheral blood 

blasts 

MDS-SLD 1 1-2 < 15% / < 5% b BM


Chapter 13: 

Myelodysplastic / 


Neoplasms 


Chapter 13: 

Myelodysplastic / 


Neoplasms 


Chapter 13.1: Chronic Myelomonocytic Leukemia 

Nupur Sharma 


Figure 1: WHO CRITERIA FOR CMML 

1. Persistent PB monocytosis (≥1 x 10 9 /L) with monocytes 

accounting for ≥ 10% of the leukocytes 

2. WHO criteria for BCR-ABL1-positive chronic myeloid 

leukemia, primary myelofibrosis, polycythemia vera and 

essential thrombocythemia a are not met 

3. No rearrangement of PDGFRA, PDGFRB or FGFR1 and no 

PCM1-JAK2 (which should be specifically excluded in 

cases with eosinophilia) 

4. Blasts b constitute

● Micromegakaryocytes and/or megakaryocytes 

with hyposegmented nuclei are found in most 

cases 

● Nodules composed of mature plasmacytoid 

dendritic cells in the bone marrow biopsy have 

been reported in few cases 

● Apoptotic bodies, often within starry sky 

histiocytes are seen 

● Splenomegaly due to infiltration of the red pulp 

by leukemic cells 

● Lymphadenopathy: indicates transformation to 

a more acute phase, and the lymph node may 

show diffuse infiltration by myeloid blasts 


● Positive: CD13 and CD33 

● Decreased CD14 expression may reflect relative 

monocyte immaturity 

● Other aberrant characteristics include 

overexpression of CD56; aberrant expression of 

CD2; and decreased expression of HLA-DR, CD13, 

CD11c, CD15, CD16, CD64 and CD36 

● Lysozyme used in conjunction with 

cytochemistry for CAE can facilitate the 

identification of monocytic cells, which are 

lysozyme positive, but CAE negative (in contrast 

to the granulocyte precursor cells, which are 

positive for both) 

● Plasmacytoid dendritic cells: Positive for CD123, 

CD2AP, CD4, CD43, CD45RA, CD68/CD68R, 

CD303, BCL11A and granzyme B 

GENETICS 

● Gain of chromosome 8 and loss of chromosome 

7 or del(7q) are common 

● TET2 and SRSF2: more frequent as compared to 

ASXL 

● p190 isoform of CML: presents as monocytosis 

(do karyotype/FISH/RT-PCR) 

● Cases with NPM1 mutation (exclude alternative 

diagnosis of AML with NPM1 mutation first) have 

a high probability of progressing to AML 


● Median survival time in months 

● Progression to AML (AML-MRC) occurs in some 

cases 

● Percentage of blood and bone marrow blasts is 

the most important factor determining survival, 

together with karyotype, WBC count, and 

hematopoietic function 

● Clinical and hematological parameters including 

lactate dehydrogenase level, splenomegaly, 

anemia, thrombocytopenia, and lymphocytosis 

are important factors for predicting the course 

of the disease 

Figure 1 


Chapter 13.2: Atypical Chronic Myeloid Leukemia, BCR-ABL 

Negative 

INTRODUCTION 

Table 1: Diagnostic WHO criteria for Atypical Chronic 

Myeloid Leukemia, BCR-ABL-negative (aCML) 

• Peripheral Blood Leukocytosis ≥13 X 10 9 /L, due to 

increased numbers of neutrophils and their precursors 

(i.e., promyelocytes, myelocytes, and metamyelocytes), 

with neutrophil precursors constituting ≥ 10% of the 

leukocytes 

• Dysgranulopoiesis, which may include abnormal 

chromatin clumping 

• No or minimal absolute basophilia; basophils constitute 

< 2% of the peripheral blood leukocytes 

• No or minimal absolute monocytosis; monocytes 

constitute

● Abnormalities in chr 13, 14, 17, 19, 12 


● Variable 

● Poor, median survival in months, BMT improves 

outcomes 


‣ Age >65 years, 

‣ Female gender, 

‣ High leukocyte count >50 x 10 9 /L, 

‣ Anemia (Hb

Chapter13.3: Juvenile Myelomonocytic Leukemia (JMML) 

Nidhi Kataria Kshitija Kale Akanksha Gupta 

Table 1: WHO diagnostic criteria for JMML 

● Clinical and hematological criteria (all 4 required) 

1. Peripheral blood monocyte count ≥1 x10 9 /L 

2. Blast percentage in peripheral blood and bone 

marrow of


● Monocytes: Lysozyme and CD68R positive 

● Granulocytic: MPO+ 

● Hypersensitivity to G-CSF 

GENETICS 

● Karyotype - Normal (>½ cases), monosomy 7 (¼ 

cases), other abnormalities (some cases) 

● Molecular – Aberrant signal transduction of RAS 

signaling pathway 

● Driver mutations in PTPN11, NRAS, KRAS, CBL, 

and NF1 (Table 1) 

Table 2: Genetic alterations in JMML 

RAS -o-genic gene mutations 

PTPN11 NF1 NRAS, KRAS CBL 

Frequency 35% 10% 20-25% 15% 15% 

Mutation 

Somatic, heterozygous, 

gain-of-function 

LOH 

Somatic, 

heterozygous, codon 

12,13,61 

Germline, missense 

alterations in linker 

region/ring-finger 

domain (exon 8,9), 

duplication of 

mutant CBL through 

uniparental disomy 

Germline, 

heterozygous, splicesite 

mutation 

RAS 

negative 

No 

mutations 

Secondary 

abnormalities 

Occur in addition to 

RAS 

1. RAS double 

mutants (second 

hits in other RAS 

genes) 

2. SETBP1 

3. JAK3 

4. SH2B3 

5. ASXL1 

6. Genes of 

polyclonal repressor 

complex 


Prognosis 

● Rapidly fatal in cases with PTPN11 and NF1 

mutations 

‣ Short median survival without SCT 

‣ Shorter survival if low platelet count, age >2 

years or ↑HbF 

● Aggressive course in KRAS/NRAS (warrants early 

SCT) 

‣ Longer survival if ↓HbF, normal to moderate 

↓ platelets or no subclonal mutations 

● Spontaneous regression in CBL 

‣ Aggressive course if secondary genetic changes 


Chapter 13.4: Myelodysplasia/Myeloproliferative neoplasm 

with Ring Sideroblasts and Thrombocytosis 

Nupur Sharma 


Table 1: WHO criteria for MDS/MPN-RS-T 

• Anemia associated with erythroid-lineage dysplasia, with or 

without multilineage dysplasia 

• ≥15% ring sideroblasts a ,

Chapter 13.5: Myelodysplasia/Myeloproliferative 

neoplasm, Unclassifiable (MDS/MPN-U) 

Nupur Sharma 


INTRODUCTION 

Table 1: WHO criteria for MDS/MPN, Unclassifiable 

• Myeloid neoplasm with mixed myeloproliferative and 

myelodysplastic features at onset, not meeting the WHO 

criteria for any other myelodysplastic/myeloproliferative 

neoplasm, myelodysplastic syndrome, or myeloproliferative 

neoplasm 

•



Nupur Sharma 


Chapter 14-21: Other 

High Yield Topics 




Nupur Sharma 



Chapter 14: Mastocytosis 

INTRODUCTION 

Table 1: WHO Classification of mastocytosis variants 

Cutaneous mastocytosis 

● Urticaria pigmentosa/maculopapular cutaneous 

mastocytosis 

● Diffuse cutaneous mastocytosis 

● Mastocytoma of skin 

Systemic mastocytosis 

● Indolent systemic mastocytosis a (including the bone 

marrow mastocytosis subtype) 

● Smoldering systemic mastocytosis a 

● Systemic mastocytosis with an associated hematological 

neoplasm b 

● Aggressive systemic mastocytosis a 

● Mast cell leukemia 

Mast cell sarcoma 

a The complete diagnosis of these variants requires 

information regarding B and C findings, all of which may not 

be available at the time of initial tissue diagnosis. 

b This variant is equivalent to the previously described entity 

‘systemic mastocytosis with an associated clonal 

hematological non-mast cell lineage disease’, and the terms 

can be used synonymously 


Edition, Volume 2, Horny H P et al. Mastocytosis, Page No. 62, 2017 

INTRODUCTION 

● Clonal, neoplastic proliferation of mast cells that 

accumulate in one or more organ systems 

CUTANEOUS MASTOCYTOSIS 

● Diagnosis of cutaneous mastocytosis (CM) 

requires the demonstration of typical clinical 

findings and histological proof of abnormal 

mast cell infiltration of the dermis 

● No systemic involvement in the bone marrow or 

any other organ 

● Diagnostic criteria for systemic mastocytosis are 

not fulfilled 

● 3 major variants of cutaneous mastocytosis 

‣ Urticaria pigmentosa/maculopapular 

cutaneous mastocytosis 

‣ Diffuse cutaneous mastocytosis 

‣ Mastocytoma of skin 

Demographics 

Nupur Sharma Aakash Bhatia 


● Most common in children and can be present at 

birth 

● Common before the age of 6 months 

● Less common in adults 


● Darier’s sign: lesions of all forms may urticate 

when stroked 

● Intraepidermal accumulation of melanin 

pigment 

● The term ‘urticaria pigmentosa’ describes these 

two clinical features macroscopically 

● Blistering in patients aged adults 

● Aggregates of spindle-shaped mast cells filling 

papillary dermis, and extending to reticular 

dermis often in periadnexal and perivascular 

spaces 

● Adults: disseminated lesions more common, 

associated with systemic mastocytosis 

● Skin lesions in childhood cutaneous mastocytosis 

show KIT D816V mutations 

DIFFUSE CUTANEOUS MASTOCYTOSIS 

● Exclusive to childhood 

● Less common 

● Grain leather (peau chagrine) or orange peel 

(peau d'orange) appearance of skin 

● No individual lesions 

● Biopsy shows a band-like infiltrate of mast cells 

in the papillary and upper reticular dermis 

MASTOCYTOMA OF SKIN 

● Typically occurs as single lesion and is exclusive 

to childhood 

● Sheets of spindle-shaped mast cells without 

atypia seen filling papillary dermis, reticular 

dermis and may extend to subcutaneous tissues 

● Absence of cytological atypia helps distinguish 

from rare mast cell sarcoma of the skin 


The diagnosis of systemic mastocytosis can be made when the major criterion and at least 1 minor 

criterion are present, or when ≥3 minor criteria are present 

Figure 1 

SYSTEMIC MASTOCYTOSIS 

● Consensus criteria for the diagnosis of systemic 

mastocytosis have been established, and include 

major and minor criteria (Table 2) 

● Five variants are recognized: 

‣ Indolent systemic mastocytosis 

‣ Smoldering systemic mastocytosis 

‣ Systemic mastocytosis with associated 

hematological neoplasm 

‣ Aggressive systemic mastocytosis 

‣ Mast cell leukemia 

Demographics 

● Generally diagnosed after the 2 nd decade of life 

● In systemic mastocytosis, BM is almost always 

involved 

● Morphological and molecular analysis of a BM 

biopsy specimen is strongly recommended in 

adults, to confirm or exclude the diagnosis 

● Mediator-related systemic events: abdominal 

pain, gastrointestinal distress, syncope, 

headache, hypotension, tachycardia, respiratory 

symptoms 

● Musculoskeletal symptoms: bone pain, 

osteopenia/osteoporosis, fractures, arthralgias, 

myalgias 

● Organomegaly is usually present with impaired 

organ function in advanced systemic 

mastocytosis 

● Mast cell activation syndrome (MCAS) is seen in 

patients with severe mediator-related 

symptoms, and increased serum tryptase levels. 

NOT diagnostic of systemic mastocytosis 


● Presenting symptoms of systemic mastocytosis 

have been grouped into four categories 

● Constitutional symptoms: fatigue, weight loss, 

fever, diaphoresis 

● Skin manifestations: pruritus, urticaria, 

dermatographism, flushing 


Table 2: Diagnostic criteria for cutaneous and systemic 

mastocytosis 

Cutaneous mastocytosis 

Skin lesions demonstrating the typical findings of urticaria 

pigmentosa/maculopapular cutaneous mastocytosis, diffuse 

cutaneous mastocytosis or solitary mastocytoma, and typical 

histological infiltrates of mast cells in a multifocal or diffuse 

pattern in an adequate skin biopsy a 

In addition, features/criteria sufficient to establish the diagnosis 

of systemic mastocytosis must be absent 

Systemic mastocytosis 

The diagnosis of systemic mastocytosis can be made when the 

major criterion and at least 1 minor criterion are present, or 

when ≥3 minor criteria are present 

Major criterion 

Multifocal dense infiltrates of mast cells (≥15 mast cells in 

aggregates) detected in sections of bone marrow and/or other 

extracutaneous organ(s) 

Minor criteria 

1. In biopsy sections of bone marrow or other extracutaneous 

organs, >25% of the mast cells in the infiltrate are spindleshaped 

or have atypical morphology or >25% of all mast cells in 

bone marrow aspirate smears are immature or atypical. 

2. Detection of an activating point mutation at codon 816 of KIT 

in the bone marrow, blood or another extracutaneous organ 

3. Mast cells in bone marrow, blood or another extracutaneous 

organ express CD25, with or without CD2, in addition to normal 

mast cell markers b 

4. Serum total tryptase is persistently >20 ng/mL, unless there is 

an associated myeloid neoplasm, in which case this parameter 

is not valid. 


● Anemia, leukocytosis, eosinophilia (common 

finding), neutropenia and thrombocytopenia 

● Hematological neoplasm associated with 

systemic mastocytosis (CMML and MDS/MPN-U 

are most common) 

Bone marrow 

● Multifocal clusters of cohesive aggregates of 

mast cells in 2 patterns: 

‣ Diffuse loose clusters, interstitial pattern 

along with activating point mutations in KIT 

‣ Multifocal compact mast cell infiltrates, or 

diffuse compact mast cell infiltrates 

Figure 2 

a This criterion applies to both the dense focal and the diffuse 

mast cell infiltrates in the biopsy. 

b CD25 is the more sensitive marker, by both flow cytometry and 

immunohistochemistry. 

Reprinted with permission from WHO Classification of Tumours of 

Hematopoietic and Lymphoid Tissues, Revised 4th ed, volume 2, Swerdlow SH 

et al, Mastocytosis, Page 63, 2017 

● Monoclonal MCAS: Diagnostic criteria for 

systemic mastocytosis are not fulfilled, but clonal 

mast cells with the KIT D816V mutation or 

aberrant surface CD25 are found 

● Primary (clonal) MCAS: Patients with monoclonal 

MCAS and those with mediator-related 

symptoms and systemic mastocytosis 

● Presence of MCAS needs to be documented as it 

has clinical and therapeutic implications 

Figure 3 


CD117 Tryptase CD25 

Figure 4 

Figure 5 

INDOLENT SYSTEMIC MASTOCYTOSIS (Including Bone 

Marrow Mastocytosis subtype) 

● Mast cell burden is usually low, and skin lesions 

are found in most patients 

● For cases that fulfill the criteria for indolent 

systemic mastocytosis and also present with one 

B finding, the diagnosis remains indolent 

systemic mastocytosis 

● If two or more B findings are detected, the 

diagnosis changes to smoldering systemic 

mastocytosis 

● KIT D816V mutation is present in >90% of typical 

indolent systemic mastocytosis cases 

● In bone marrow mastocytosis subtype burden of 

neoplastic mast cells is usually low, and serum 

tryptase levels are often normal 

Figure 6 

SMOLDERING SYSTEMIC MASTOCYTOSIS 

● Mast cell burden is high, organomegaly is often 

found, and multilineage involvement is typically 

present 


Table 3: Diagnostic criteria of mastocytosis 

Indolent systemic mastocytosis 

‣ Meets the general criteria for systemic mastocytosis 

‣ No C findings a 

‣ No evidence of an associated hematological neoplasm 

‣ Low mast cell burden 

‣ Skin lesions are almost invariably present 

Bone marrow mastocytosis 

‣ As above (indolent systemic mastocytosis), but with 

bone marrow involvement and no skin lesions 

Smoldering systemic mastocytosis 


‣ ≥ 2 B findings; no C findings a 

‣ No evidence of an associated hematological neoplasm 

‣ High mast cell burden 

‣ Does not meet the criteria for mast cell leukemia 

Systemic mastocytosis with associated hematological 

neoplasm 


‣ Meets the criteria for an associated hematological 

neoplasm (i.e., a myelodysplastic syndrome, 

myeloproliferative neoplasm, acute myeloid leukemia, 

lymphoma, or another hematological neoplasm 

classified as a distinct entity in the WHO classification) 

Aggressive systemic mastocytosis 


‣ ≥ 1 C finding a 

‣ Does not meet the criteria for mast cell leukemia 

‣ Skin lesions are usually absent 

Mast cell leukemia 


‣ Bone marrow biopsy shows diffuse infiltration (usually 

dense) by atypical, immature mast cells 

‣ Bone marrow aspirate smears show ≥20% mast cells 

‣ In classic cases, mast cells account for ≥10% of the 

peripheral blood white blood cells, but the aleukemic 

variant (in which mast cells account for

● In most cases, skin lesions are absent 

● C findings indicative of organ damage caused by 

the malignant mast cell infiltration, are usually 

present at diagnosis 

● May harbor atypical KIT mutations, like non- 

D816V codon or non-codon 816 mutations 

● If KIT D816V mutations are absent, KIT gene is 

sequenced for non-codon 816 mutations 

Additional mutations are TET2, SRSF2 & CBL 

Figure 9 

Figure 7 

Figure 8 

MAST CELL SARCOMA 

● Also called malignant mastocytoma 

● Extremely rare entity characterized by localized 

destructive growth of highly atypical mast cells, 

identified only by appropriate IHC markers, like 

tryptase and KIT (CD117) 


● Reactive and neoplastic mast cells express 

tryptase, CD117, CD33, and CD43 

● Neoplastic mast cells aberrantly coexpress 

CD25, ± CD2, and CD30 (also detected by flow 

cytometry) 

Genetics 

● KIT D816V is the most common mutation 

in mastocytosis 

● TET2 mutations present in some cases and 

correlated with aggressive behavior in systemic 

mastocytosis 


Prognosis 

● Variable and depends on subtypes 

● Cutaneous and indolent systemic mastocytosis 

have an indolent clinical course 

● Remaining variants have an aggressive clinical 

course 


TO DIFFERENTIATE FROM NORMAL MAST CELLS: 

● Normal mast cells are scattered loosely 

throughout the sample; show clumped 

chromatin, low NC ratio, and absent/indistinct 

nucleoli, cytoplasm abundant 

● Neoplastic mast cells are spindle, hypogranular 

with cytologic atypia, and metachromatic blast 

cells (a typical feature of mast cell leukemia) 

● Promastocytes (bilobed or multilobed mast cells) 

associated with aggressive disease 

● Serum tryptase: >20 ng/ml persistently elevated 

in systemic mastocytosis, while normal or slightly 

increased in cutaneous mastocytosis 

● Cytochemistry: Giemsa, toluidine blue stains to 

show metachromatic granules. CAE may be 

positive, but MPO is negative 


Chapter 15: Myeloid/lymphoid neoplasms with eosinophilia 

and gene rearrangements 

Nupur Sharma Aakash Bhatia Kshitija Kale Akanksha Gupta 

INTRODUCTION 

● The provisional category of myeloid/lymphoid 

neoplasms with eosinophilia and rearrangement 

of PDGFRA, PDGFRB or FGFR1, or with PCM1- 

JAK2 contains three specific rare disease groups 

● Some features are shared, and others differ, but 

all the neoplasms result from the formation of a 

fusion gene, or (rarely) from a mutation, 

resulting in the expression of an aberrant 

tyrosine kinase 

● Eosinophilia is characteristic, but not invariable 

MYELOID/LYMPHOID NEOPLASMS WITH PDGFRA 

REARRANGEMENT 

Table 1: WHO CRITERIA - Diagnostic criteria for 

myeloid/lymphoid neoplasms with eosinophilia associated 

with FIP1L1-PDGFRA or a variant fusion gene* 

● A myeloid or lymphoid neoplasm, usually with 

prominent eosinophilia 

AND 

● The presence of FIP1L1-PDGFRA fusion gene or a variant 

fusion gene with rearrangement of PDGFRA or an 

activating mutation of PDGFRA** 

● 

● 

* Cases presenting as a myeloproliferative neoplasm, 

acute myeloid leukemia, or lymphoblastic 

leukemia/lymphoma with eosinophilia and FIP1L1- 

PDGFRA gene fusion are assigned to this category 

** If appropriate molecular analysis is not possible, this 

diagnosis should be suspected if there is a 

myeloproliferative neoplasm with no Philadelphia (Ph) 

chromosome and with the hematological features of 

chronic eosinophilic leukemia associated with 

splenomegaly, marked elevation of serum vitamin B12, 

elevation of serum tryptase, and an increased number of 

bone marrow mast cells 

Reprinted with permission from WHO Classification of Tumours of Hematopoietic and 

Lymphoid Tissues, Revised 4th ed, volume 2, Swerdlow SH et al, Myeloid/lymphoid 

neoplasms with eosinophilia and gene rearrangements, Page 73, 2017 

Demographics 

● FIP1L1-PDGFRA syndrome is rare 

● Middle-aged adults, male predominance 


● Peripheral blood, bone marrow, tissue 

infiltration common 


● Can be asymptomatic 

● Fatigue or pruritus, or with respiratory, cardiac, 

or gastrointestinal symptoms, splenomegaly, 

hepatomegaly 

● Endomyocardial fibrosis with restrictive 

cardiomyopathy 

● Scarring of the mitral and/or tricuspid valves 

leads to valvular regurgitation and the 

formation of intracardiac thrombi, which may 

embolize 

● Venous thromboembolism and arterial 

thrombosis can also occur 

● Pulmonary disease is restrictive and related to 

fibrosis; symptoms include dyspnea and cough 

● Serum tryptase is elevated (>12 ng/ml), and 

serum vitamin B 12 is markedly elevated 


● Peripheral blood eosinophilia 

● Hypercellular BM with markedly increased 

numbers of eosinophils and precursors 

● Some cases show a marked increase in spindleshaped 

atypical mast cells 


● Eosinophils: CD23, CD25 and CD69 positive 

● Mast cells: CD2 negative and CD25 positive, but 

in some cases, they are negative for both and in 

occasional cases they are positive for both (mast 

cells of systemic mastocytosis are CD25 positive 

in almost all cases) 

GENETICS 

● FIP1L1-PDGFRA fusion gene resulting from a 

cryptic del(4) or a chromosomal rearrangement 

with a 4q12 breakpoint 


● FIP1L1-PDGFRA associated CEL is very responsive 

to imatinib 

● Imatinib resistance can develop (e.g., because of 

a T6741 mutation) 

● Alternative tyrosine kinase inhibitors such as 

midostaurin and sorafenib may be effective 


MYELOID/LYMPHOID NEOPLASMS WITH PDGFRB 

REARRANGEMENT 

Table 2: WHO CRITERIA: Diagnostic criteria for 

myeloid/lymphoid neoplasms associated with ETV6- 

PDGFRB or other rearrangement of PDGFRB a 

● A myeloid or lymphoid neoplasm, often with 

prominent eosinophilia and sometimes with 

neutrophilia or monocytosis 

AND 

● Presence of t(5;12)(q32;p13.2) or a variant 

translocation a,b or demonstration of ETV6-PDGFRB 

fusion gene or other rearrangement of PDGFRB b 

● a- Cases with fusion genes typically associated only 

with BCR-ABL1-like B-lymphoblastic leukemia are 

specifically excluded 

● b- Because t(5;12)(q32;p13.2) does not always result in 

ETV6-PDGFRB fusion, molecular confirmation is highly 

desirable; if molecular analysis is not possible, this 

diagnosis should be suspected if there is a 

myeloproliferative neoplasm associated with 

eosinophilia, with no Philadelphia (Ph) chromosome 

and with a translocation with a 5q32 breakpoint 


Hematopoietic and Lymphoid Tissues, Revised 4th ed, volume 2, Swerdlow 

SH et al, Myeloid/lymphoid neoplasms with eosinophilia and gene 

rearrangements, Page 75, 2017 

Demographics 

● Middle-aged adults, male predominance 


● Peripheral blood, bone marrow, tissue 

infiltration common 


● Splenomegaly, hepatomegaly 

● Skin infiltration, cardiac damage leading to 

cardiac failure 

● Serum tryptase may be mildly or moderately 

elevated 


Morphology 

● Leukocytosis, anemia, and thrombocytopenia 

● BM is hypercellular because of active 

granulopoiesis 

● Variable increase in eosinophils, neutrophils, 

and monocytes 

● Increase in spindled mast cells 


● Positive: CD2 and CD25 in mast cell disease 

GENETICS 

● t(5;12) with the translocation resulting in ETV6- 

PDGFRB gene fusion (previously called TEL- 

PDGFRB) 

● Cases without a fusion gene are not assigned to 

this category of MPN and are not likely to 

respond to imatinib 

● If molecular analysis is not available, a trial of 

imatinib is justified in patients with an MPN 

associated with t(5;12) 


● Depends on early diagnosis and treatment 

MYELOID/LYMPHOID NEOPLASMS WITH FGFR1 

REARRANGEMENT 

Table 3: WHO CRITERIA: Diagnostic criteria for 

myeloid/lymphoid neoplasms with FGFR1 rearrangement 

● A myeloproliferative or 

myelodysplastic/myeloproliferative neoplasm with 

prominent eosinophilia and sometimes with neutrophilia 

or monocytosis 

OR 

● Acute myeloid leukemia, T- or B-lymphoblastic 

leukemia/lymphoma, or mixed-phenotype acute 

leukemia (usually associated with peripheral blood or 

bone marrow eosinophilia) 

AND 

● The presence of t(8;13)(p11.2;q12) or a variant 

translocation leading to FGFR1 rearrangement 

demonstrated in myeloid cells, lymphoblasts or both 


Hematopoietic and Lymphoid Tissues, Revised 4th ed, volume 2, Swerdlow 

SH et al, Myeloid/lymphoid neoplasms with eosinophilia and gene 

rearrangements, Page 78, 2017 

Demographics 

● Young adults, male predominance 


● Peripheral blood, BM, tissue infiltration common 



● Some cases present as lymphoma with mainly 

lymph node involvement or with a mediastinal 

mass 

● Others present with myeloproliferative features, 

such as splenomegaly, hypermetabolism, or with 

features of acute myeloid leukemia or myeloid 

sarcoma 

MORPHOLOGY 

● Features of chronic eosinophilic leukemia, acute 

myeloid leukemia, T-lymphoblastic 

leukemia/lymphoma, or (least often) B- 

lymphoblastic leukemia/ lymphoma or mixedphenotype 

acute leukemia 

● Patients who present in chronic phase have 

eosinophilia and neutrophilia and occasionally 

have monocytosis 

● Variable 

GENETICS 

● Translocations with an 8p11 breakpoint, trisomy 

21 


● Due to the high incidence of transformation, the 

prognosis is poor, even for patients presenting in 

the chronic phase 

● No established tyrosine kinase inhibitor therapy 

for myeloproliferative neoplasms with FGFR1 

rearrangement 

MYELOID/LYMPHOID NEOPLASMS WITH PCM1 - JAK2 

● Variants: ETV6-JAK2, BCR-JAK2 

Demographics 

● Affects adults, male predominance 

MORPHOLOGY 

● Eosinophilia and neutrophil precursors may be 

present in the peripheral blood 

● BM: dysgranulopoiesis, dyserythropoiesis 

GENETICS 

● t(8,9),(9,12) or t(9,22) 

PROGNOSIS 


PDGFRA PDGFRB FGFR-1 PCM1-JAK2 

Presentation 

Genetics 

Diagnostic criteria 

Presentation 

- CEL with mast cells/ 

neutrophils 

- AML 

- T-ALL 

- B-ALL 

FIP1L1-PDGFRA fusion gene 

resulting from a cryptic 

del(4)(q12) 

A myeloid or lymphoid 

neoplasm, usually with 

prominent eosinophilia and 

presence of FIP1L1-PDGFRA 

fusion gene or a variant 

fusion gene with 

rearrangement of PDGFRA 

or an activating mutation 

of PDGFRA 

Fatigue, pruritis, 

splenomegaly, endocardial 

fibrosis, Restrictive cardiomyopathy, 

valve scarring 

- CMML with eosinophilia 

with/out aberrant mast 

cells 

- AML 

t(5;12) with the 

translocation resulting in 

ETV6-PDGFRB gene 

fusion 

A myeloid or lymphoid 

neoplasm, with 

prominent eosinophilia 

and sometimes with 

neutrophilia or 

monocytosis & presence 

of t(5;12) or a variant 

translocation or 

demonstration of ETV6- 

PDGFRB fusion gene or 

other rearrangement of 

PDGFRB 

Splenomegaly, tissue 

infiltration by 

eosinophils, cardiac 

failure 

Peripheral Blood Eosinophilia High WBC count, anemia, 

Thrombocytopenia 

Bone marrow 

Hypercellular, increased 

eosinophils and precursors, 

mast cell proliferation and 

reticulin fibrosis. 

CD23, CD25, CD69 positive, 

CD2 negative 

Hypercellular, increase in 

mast cells (spindle 

shaped), reticulin fibrosis 

Mast cells CD2 and CD25 

positive 

- Lymphomatous 

- T-ALL 

- CEL 

- B-ALL 

- AML 

Translocations with an 

8p11 breakpoint, 

trisomy 21/FGFR 

rearrangement 

MPN or MPN/MDS 

with eosinophilia and 

sometimes with 

neutrophilia or 

monocytosis OR AML, 

T- or B-ALL/lymphoma, 

or mixed-phenotype 

acute leukemia and 

presence of t(8;13) or 

variant translocation 

leading to FGFR1 

rearrangement, 

demonstrated in 

myeloid cells, 

lymphoblasts, both 

Splenomegaly, 

hypermetabolism 

Features of respective 

myeloid neoplasm. 

Patients who present in 

chronic phase have 

eosinophilia and 

neutrophilia and 

occasionally have 

monocytosis 

Features of respective 

myeloid neoplasm 

-Myeloblastic/ 

lymphoblastic 

transformation 

t(8,9),(9,12) or t(9,22) 

ETV6-JAK2, BCR-JAK2 

Hepatosplenomegaly 

Eosinophilia, and 

neutrophil precursors 


Hypercellular, 

dysgranulopoiesis, 

dyserythropoiesis 

Prognosis 

Very responsive to 

imatinib; (100Xmore 

responsive than BCR-ABL1) 

Improved survival with 

Imatinib 

Poor prognosis 

No role of TKI drugs 

Variable, responsive to 

TKI (ruxolitinib) 


Chapter 16: Myeloid neoplasms with germline 

predisposition 

Akanksha Gupta Nupur Sharma 

INTRODUCTION 

Table 1: Classification of myeloid neoplasms with germ line 

predisposition 

Myeloid neoplasms with germline predisposition without a 

pre-existing disorder or organ dysfunction 

• AML with germline CEBPA mutation 

• Myeloid neoplasms with germline DDX41 mutation 

Myeloid neoplasms with germline predisposition and preexisting 

platelet disorders 

• Myeloid neoplasms with germline RUNX1 mutation 

• Myeloid neoplasms with germline ANKRD26 mutation 

• Myeloid neoplasms with germline ETV6 mutation 

Myeloid neoplasms with germline predisposition and other 

organ dysfunction 

• Myeloid neoplasms with germline GATA2 mutation 

• Myeloid neoplasms associated with bone marrow failure 

syndromes 

• Myeloid neoplasms associated with telomere biology 

disorders 

• Juvenile myelomonocytic leukemia associated with 

neurofibromatosis, Noonan syndrome, or Noonan 

syndrome-like disorders 

• Myeloid neoplasms associated with Down syndrome 


Hematopoietic and Lymphoid Tissues, Revised 4th ed, volume 2, 

Peterson L et al, myeloid neoplasms with germ line predisposition, Page 

123, 2017 

● Myeloid neoplasms that occur in association 

with inherited or de novo germline mutations 

and have specific genetic and clinical findings 

(Table 1, Table 2) 

● Important to distinguish germline versus 

sporadic/secondary myeloid neoplasms as 

‣ Long term follow-up is required in the 

absence of overt neoplasm 

‣ Associated organ dysfunction and platelet 

disorder warrant treatment 

‣ Genetic counselling from trained personnel 

is beneficial 

‣ Careful donor selection for SCT is critical to 

avoid poor/failed engraftment, poor graft 

function, and donor-derived leukemias 

Demographics 

● Pre-existing disorder: children/young adults 

● Neoplasm: older adults 


● Positive family history 


● Standard diagnostic features of 

MDS/AML/Lymphoid neoplasm 

● Signs of progression to MDS/AML (In case of preexisting 

disorder) – 

● ↑ Blasts, ↑ BM cellularity with persistent 

cytopenias, ↑ cytopenia, additional 

cytogenetic/molecular lesions 

● Caveats 

‣ Early dysplastic features may remain stable 

for years (e.g., in ETV6, ANKRD26) 

‣ Fluctuating clonal hematopoiesis can be seen 

(e.g., in Fanconi’s anemia) 

‣ If genetic predisposition is unknown at 

baseline, diagnosis can be modified to MNGP 

later 

‣ Myeloid neoplasm in childhood syndromes 

should be classified as ‘AML with xxx 

mutation’ or ‘AML with xxx syndrome’ (if 

mutation not identified) 

GENETICS 

● Cytogenetics may be normal/ non-specific 

● Germline testing on constitutional DNA as 

mutations can occur as both germline/ acquired 

events 

● Sample for germline testing: 

‣ Skin fibroblasts - Gold standard, may use nails/ 

hair 

‣ PB/BM - Caution as both affected by 

hematological tumors 

‣ Saliva/buccal swabs - Caution as often 

contaminated with WBCs 

● Panel-based testing for all known genes 

● Sometimes, unique mutations are identified in a 

family and classified as “VUS- variants of uncertain 

significance” followed by functional testing to 

see if the mutations are pathogenic 

● Syndromes associated with germline 

predisposition: 


‣ Fanconi anemia 

‣ Severe congenital neutropenia 

‣ Shwachman-Diamond syndrome 

‣ Diamond - Blackfan anemia 

‣ Telomere biology disorders including 

dyskeratosis congenita and syndromes due to 

TERC or TERT mutation 

‣ All the above syndromes are associated with 

congenital anomalies and may evolve to 

MDS/AML 

Syndromes associated with GATA2 mutation: (now 

recognized as a spectrum of a single genetic disorder) 

1. MonoMAC syndrome: Monocytopenia and non 

- TB mycobacterial infection 

2. DCML deficiency: Dendritic cell, monocyte, B- 

and NK lymphoid deficiency: vulnerability to 

viral infections 

3. Familial MDS/AML 

4. Emberger syndrome: primary lymphoedema, 

warts, predisposition to MDS/AML also, a 

minority of cases of congenital neutropenia/ 

aplastic anemia 


Mutated 

gene 

Region Inheritance Median age for 

MN 

CEBPA 19q13.1 AD Children, 

young adults 

Comorbidity Type of HLN Features 

None AML -Germline at 5’, somatic at 

3’ end of other allele 

-Acquired GATA2 common 

-Favorable prognosis 

(in biallelic) despite multiple 

relapses occurring due to 

novel, independent clones 

DDX41 5q35.3 AD Older adults None MDS, AML, 

rarely CML, 

CMML, HD, NHL, 

myeloma 

RUNX1 21q22.12 AD Middle age -Low platelets (mild) 

-Impaired aggregation 

with 

collagen/epinephrine 

-Dense granule 

deficiency 

ANKRD26 10p12.1 AD - Low platelets (moderate) 

- Normal aggregation 

-Alpha granule, GPIa 

deficiency 

- ↑TPO 

ETV6 12p13.2 AD Infancy 

(occasionally) 

Low platelets (variable) 

AML, MDS, 

rarely CMML, 

T-ALL, hairy-cell 

leukemia 

AML, MDS, 

rarely CML, 

CMML, CLL 

B-ALL, AML, 

MDS, CMML, 

myeloma, PV, 

solid tumors 

GATA2 3q21.3 AD Young adults Organ dysfunction AML, MDS 

(especially in 

childhood), 

CMML, aCML 

-Usually biallelic 

-Leukopenia, hypocellular 

BM, AML-M6 

-Poor prognosis 

-Haploinsufficiency, 

dominant negative effects 

-Second hit mutation in 

other allele 

Disease of ‘variables’ 

- variable clinical 

presentation 

- variable age of 

presentation 

- variable age of progression 

-variable rate of progression 

to MDS/AML 

-Also known as 

“Thrombocytopenia 2” 

-BM hyposegmented/ 

micromegakaryocytes 

-MAPK inhibitors reverse 

proplatelet defect 

Thrombocytopenia 

-Missense mutations lead to 

dominant negative effect 

Concurrent ASXL-1 mutation 

in patients with monosomy 7 

-Poor prognosis 


Chapter 17: Post-Transplant Lymphoproliferative Disorder 

(PTLD) 

Nupur Sharma 


INTRODUCTION 

● Lymphoid or plasmacytic proliferations seen in 

solid organ or stem cell allograft due to 

immunosuppression 

Table 1: Categories of PTLD 

Non-destructive PTLDs 

Plasmacytic hyperplasia 

Infectious mononucleosis 

Florid follicular hyperplasia 

Polymorphic PTLD 

Monomorphic PTLDs a 

(classify according to lymphoma they resemble) 

B-cell neoplasms 

Diffuse large B-cell lymphoma 

Burkitt lymphoma 


Plasmacytoma 

Other b 

T-cell neoplasms a 

Peripheral T-cell lymphoma, NOS 

Hepatosplenic T-cell lymphoma 

Other 

Classic Hodgkin lymphoma PTLD b 

a 

The ICD-0 codes for these lesions are the same as those for the 

respective lymphoid or plasmacytic neoplasm 

b Indolent small B-cell lymphomas arising in transplant 

recipients are not included among the PTLDs, with the 

exception of EBV-positive marginal zone lymphomas 


Hematopoietic and Lymphoid Tissues, Revised 4th ed, volume 2, 

Swerdlow SH et al, Post-Transplant Lymphoproliferative Disorder, Page 

453, 2017 

Demographics 

● Most important risk factor for EBV-driven PTLD is 

EBV seronegativity at the time of transplantation 

● Frequency correlates with intensity and type of 

immunosuppressive regimen 

● Highest frequency in adults: heart-lung, lung, or 

intestinal allografts 

● In children, most cases associated with posttransplantation 

primary EBV infection 

● Stem cell allograft recipients have a low risk of 

PTLD 

● Risk of early-onset PTLD (

Table 2: Criteria used in the categorization of post-transplant lymphoproliferative disorder (PTLD) 

Type of PTLD Histopathology Immunophenotype Genetics 

IGH/TR clonal 


Cytogenetic/oncogene 

abnormalities 

Plasmacytic 

hyperplasia 

Pcl or very small mcl B- 

cell population(s) 

None 

Admixed small 

lymphocytes 

and plasma cells 

Pcl B-cells and 

admixed T-cells 

EBV+ 

Infectious 

mononucleosis 

Florid follicular 

hyperplasia 

Polymorphic 

Admixed small 

lymphocytes, plasma cells, 

and immunoblasts 

Prominent hyperplastic 

germinal centers 

Architectural effacement 

present, full spectrum of 

lymphoid maturation seen, 

not fulfilling criteria for 

NHL 



EBV+ 



EBV± 

Pcl ± mcl B-cells 

and admixed T-cells 

EBV+ mostly 


cell population(s); may 

have clonal/ oligoclonal 

TR genes 


cell population(s) 

Mcl B-cells, non-clonal T 

Cells 

Simple cytogenetic 

abnormalities rarely 

present 

Non-specific simple 

cytogenetic abnormalities 

rarely present 

Some have BCL6 somatic 


Monomorphic 


present fulfills criteria for 

NHL (other 

than the indolent B-cell 

neoplasms a ) 

Variable Clonal B-cells and/or T- 

cells 

(except for rare NK-cell 

cases) 

Variably present 

CHL 


present 

Fulfills criteria for CHL 

Similar to other 

CHL, EBV+ 

IGH not easily 

demonstrated 

Unknown 

CHL, classic Hodgkin lymphoma; NHL, non-Hodgkin lymphoma; mcl, monoclonal; Pcl, polyclonal. Monoclonality and polyclonality are only inferred when 

finding monotypic or polytypic light chain expression. a- EBV-positive MALT lymphomas at least of skin/subcutaneous tissues should be considered a type 

of PTLD 

Reprinted with permission from WHO classification of hematopoietic and lymphoid tissue, Revised 4 th ed, volume 2, Swerdlow SH et al, Post-transplant 

lymphoproliferative disorder, page 454, 2017 


Chapter 18: Other iatrogenic immunodeficiency-associated 

lymphoproliferative disorders 

INTRODUCTION 

● Lymphoid proliferations or lymphomas in patients 

treated with immunosuppressive drugs for 

autoimmune disease or conditions other than in 

the post-transplant setting 

● Range from polymorphic proliferations 

resembling polymorphic PTLDs to cases that fulfill 

the criteria for DLBCL, EBV+ DLBCL, peripheral 

T/NK-cell lymphoma, CHL, EBV positive 

mucocutaneous ulcer 

● HSTL in association with Crohn’s disease/ 

inflammatory bowel disease treated with 

infliximab and/or other TNF antagonists 

(adalimumab and etanercept), thiopurine 

currently being explored 

● latrogenically related lymphomas occurring in 

treated hematological malignancies not included 

Demographics 

● Frequency unknown 

● Factors: 

‣ Nature of the underlying disorder such as 

rheumatoid arthritis, IBD, psoriasis, psoriatic 

arthritis, SLE, other autoimmune disorders 

‣ Type and duration of immunosuppressive 

agent 

‣ Degree of immune deficiency 

‣ Degree of inflammation and/ chronic antigen 

stimulation 

‣ Host genetics 

● Methotrexate: first immunosuppressive agent 

associated with a lymphoproliferative disorder in 

rheumatoid arthritis patients 


● Extranodal sites: gastrointestinal tract, skin, liver, 

spleen, lung, kidney, adrenal gland, thyroid gland, 

bone marrow, CNS, gingiva, and soft tissue 

● HSTL: Liver, spleen, and bone marrow 


● Similar presentation of recognized lymphomas as 

in immunocompetent hosts 


Microscopy 

Priya Skaria 


● DLBCL > CHL > follicular lymphoma, Burkitt 

lymphoma, extranodal marginal zone lymphoma 

of mucosa-associated lymphoid tissue (MALT 

lymphoma), and PTCL (mostly cytotoxic and 

includes NK/T-cell lymphomas) 

● Subset: polymorphic or lymphoplasmacytic 

infiltrates resembling polymorphic PTLD 

● Increased frequency of Hodgkin lymphoma 

(mixed cellularity most common) and lymphoid 

proliferations with Hodgkin-like features, such as 

EBV-positive mucocutaneous ulcer 


● Methotrexate associated DLBCL: EBV+ activated 

B-cell type, express CD30 

● Lymphoid proliferations with Hodgkin-like 

features: large cells typically CD20+/ CD30+/ 

CD15-, EBV variably positive, with type II latency 

(LMP1 -positive and EBNA2-negative) more 

common than type Ill (LMP1-positive, EBNA2- 

positive) 

GENETICS 

● Same as recognized lymphomas with similar 

histologic subtypes not associated with 

immunosuppression 


Prognosis 

● Spontaneous regression following methotrexate 

withdrawal: associated with EBV positivity and a 

non-DLBCL type of lymphoproliferative disorder 

● Age >70 years and DLBCL type are predictive of a 

shorter survival 

● Early lymphocyte recovery is predictive of good 

response 

● HSTL: Aggressive clinical course 

Treatment 

● Discontinue methotrexate therapy 

● Relapse following regression with discontinuation 

of methotrexate therapy requires chemotherapy 

● HSTL: Allogenic bone marrow transplantation 


Chapter 19: Lymphoproliferative Diseases Associated with 

Primary Immune Disorders 

INTRODUCTION 

● Lymphoid proliferations that arise in the setting of 

primary immunodeficiency or immunoregulatory 

disorder 

● Patients with primary immune disorders (PIDs) 

are at increased risk of lymphoma 

● PIDs most frequently associated with LPDs are: 

‣ Ataxia-telangiectasia (AT) 

‣ Wiskott-Aldrich Syndrome (WAS) 

‣ Common invariable immunodeficiency (CVID) 

‣ Severe combined immunodeficiency (SCID) 

‣ X-linked lymphoproliferative disease (XLP) 

‣ Nijmegen breakage syndrome (NBS) 

‣ Hyper-IgM syndrome (HIgM) and 

‣ Autoimmune lymphoproliferative syndrome 

(ALPS) 

● Genetics, etiopathogenesis, clinical features and 

most common associated lymphoproliferative 

disorders in these PIDs are described in Table 1. 

Demographics 

● All except CVID present in the pediatric age group 

Caveat: LPD could be the initial presentation 



● Extranodal sites: GIT, lungs, CNS, liver, and skin 


Microscopy 

Non-neoplastic lesions: 

● XLP and SCID: Fatal infectious mononucleosis 

(IM) with a highly polymorphous proliferation of 

lymphoid cells, plasmacytoid and immunoblastic 

differentiation, hemophagocytic syndrome 

● CVID: Lymph nodes with follicular hyperplasia 

and EBV+ large atypical cells in paracortex, 

nodular lymphoid hyperplasia of the GIT 

● ALPS: Expansion of double-neg (CD4-/CD8- ), αβ, 

CD45RA+, CD45RO- T-cells in PB, LN, spleen, 

prominent follicular hyperplasia and PTGC 

● HIgM: Circulating B-cells with only IgM and IgD. 

Absent germinal centers in lymph nodes 

Neoplastic lesions 

Priya Skaria 


● Similar to those in immunocompetent hosts 

● DLBCL most common, others: CHL, BL, PTCL; rare 

T-ALL and T-cell prolymphocytic leukemia 

● WAS: Lymphomatoid granulomatosis, an EBV 

driven proliferation of B-cells with marked T-cell 

infiltration, CHL 

● AT and NBS: T-cell lymphomas and leukemias 

more common than B-cell lymphomas, CHL in AT 

● ALPS: NLPHL, CHL, THRLBCL 


Non-neoplastic lesions 

● ALPS: naïve T-cells CD3+, CD4-, CD8-, 45RA+, 

45RO-, CD57+/-, CD25- in PB and BM 

● HIgM: Peripheral B-cells positive for only IgM and 

IgD 

Neoplastic lesions 

● Similar to recognized lymphomas in an 

immunocompetent host 

● Mostly B-cell lymphomas; caveat: EBV infection 

of B-cells leads to downregulation of CD19, 

CD20, CD79a (negative or rare/ focal positive) 

● EBV leads to CD30 expression 

● LMP1 +/- 

● Monotypic plasma cells +/- 

GENETICS 

● Fatal IM: generally polyclonal 

● Overt lymphomas like DLBCL and BL with clonal IG 

heavy and light chain gene rearrangement 

● AT: Rearrangements and translocations of 

chromosomes 7 and 14 involving TR genes, IGH 

gene locus, and TCL1A gene are common 


● Depends on the underlying PID and type of LPD 

‣ ALPS: often self-limiting 

‣ CVID: often indolent 

‣ Most other LPD in PIDs are aggressive 

‣ Hemophagocytic syndrome often the primary 

cause of death in EBV driven IM 

‣ WAS, SCID, HIgM: Allogenic SCT 

‣ Lymphomatoid granulomatosis: anti-CD20, 

Interferon alpha 2b 


Type of Primary 

immune disorder 

Defective genes or 

proteins 

Combined T-cell and B-cell immunodeficiencies 

Severe combined 


HyperIgM syndrome 

Predominantly antibody PIDs 

Common variable 


Gamma chain of IL2R, 

IL4R, IL7R, IL9R, IL15R, 

IL21R; JAK3 kinase; IL7R, 

CD45, CD3-delta or 

CD3-epsilon RAG1/2, 

ADA 

CD40 ligand (CD40L, 

CD154) or CD40 

Other well-defined immunodeficiency syndromes 

Wiscott-Aldrich WAS (also called WASP) 

syndrome 

Mechanism 

Defects in the function of T- 

cells, B-cells, 

neutrophils, and 

macrophages 

Defects in interactions 

between T-cells & B-cells 

impairs effective 

differentiation of 

B-cells into class-switched 

plasma cells 

Most common 

abnormalities 

Recurrent severe 

bacterial, fungal, and viral 

infections, including 

opportunistic infections; 

skin rash 

Neutropenia, 

thrombocytopenia, 

hemolytic anemia, biliary 

tract and liver disease, 

opportunistic infections 

Unknown Unknown Bacterial infections, (lung, 

GIT), autoimmune 

cytopenia, granulomatous 

disease (lung, liver) 

Defects in function of T-cells, 

B-cells, neutrophils, and 

macrophages. T-cell 

dysfunction is significant, 

tends to increase in severity 

during the course of the 

disease 

Thrombocytopenia, small 

platelets, eczema, 

autoimmune disease, 

bacterial infections 

Ataxia-telangiectasia ATM Abnormal DNA repair Ataxia, telangiectasias, 

↑AFP, increased 

sensitivity to ionizing 

radiation 

Nijmegen breakage 

syndrome 

Diseases of immune dysregulation 

X-linked 


disease 

Autoimmune 


syndrome (Canale - 

Smith syndrome) 

NBN (nibrin, also called 

NBS1) 

SH2D1A 

FAS (type 1a), FASLG 

(type 1b), CASP10 (type 

2a), or CASP8 (type 2b) 

Abnormal DNA repair 

Decreased or abnormal 

signaling lymphocyte 

activation molecule (SLAM) 

associated protein (SAP) 

leads to immune 

deregulation 

Accumulation of CD4- and 

CD8- lymphoid cells in the PB 

and lymphoid tissues due to 

failure to undergo apoptosis 

Microcephaly, mental 

retardation, sensitivity to 

ionizing radiation, 

predisposition to cancer 

EBV-triggered 

abnormalities (fatal IM, 

hepatitis, aplastic anemia), 

lymphoma 

Defective lymphocyte 

apoptosis, splenomegaly, 

adenopathy, autoimmune 

cytopenia, infections 

Most common associated 

LPD 

EBV-associated lesions, 

fatal IM 

EBV-associated lesions 

(DLBCL, Hodgkin 

lymphoma), large 

granular lymphocytic 

leukemia 


(DLBCL, CHL), extranodal 

MZL, SLL, LPL, 

PTCL (rare) 


(DLBCL, Hodgkin 

lymphoma, 

lymphomatoid 

granulomatosis) 

Non-leukemic clonal T-cell 

proliferations, DLBCL, BL, 

T-PLL, T-ALL, CHL 

DLBCL, PTCL, T-ALL/LBL, 

Hodgkin lymphoma 


(BL, DLBCL) 

NLPHL, CHL, DLBCL, BL, 

PTCL (rare) (CHL, DLBCL, 

and BL may be EBV+ or 

EBV-) 

TABLE 1 

ADA, adenosine deaminase; AFP, alpha-fetoprotein; BL, Burkitt lymphoma; CHL, classic Hodgkin lymphoma; DLBCL, diffuse large B-cell 

lymphoma; IM, infectious mononucleosis; NLPHL, nodular lymphocyte predominant Hodgkin lymphoma; PTCL, peripheral T-cell 

lymphoma; T-ALL, T lymphoblastic leukemia; TALL/LBL, T-lymphoblastic leukemia/ lymphoma; T-PLL, T-cell prolymphocytic leukemia, 

CASP: Caspase 

Reprinted and modified with permission from WHO classification of hematopoietic and lymphoid tissue, Revised 4 th ed, volume 2, 

Swerdlow SH et al, Lymphoproliferative diseases associated with primary immune disorders, page 445, 2017 


Chapter 20: Lymphomas associated with HIV infection 

INTRODUCTION 

● Predominantly aggressive B-cell lymphomas 

● High proportion of first AIDS-defining illnesses 

● Most common HIV associated lymphomas include 

‣ Burkitt Lymphoma (BL) (more common in HIV 

than other immunodeficiency states) 

‣ DLBCL (often CNS) 

‣ Primary effusion lymphoma 

‣ Plasmablastic lymphoma 

‣ CHL 

Demographics 

● Incidence of all NHL subtypes increased in HIV+ 

patients; significantly decreased since 

combination antiretroviral therapy (cART) due to 

improved CD4 counts 

● Disease burden of HIV associated CHL increased 

● No known association with NLPHL 

Etiopathogenesis 

● Subtype relates to HIV status; DLBCL with lower 

CD4 counts (200 x 10 6 /L) 

● Multistep lymphomagenesis: chronic antigen 

stimulation, genetic abnormalities, cytokine 

deregulation, EBV, HHV8 

● EBV common in CHL, primary CNS lymphoma, PEL, 

DLBCL with immunoblastic features, BL 

● HHV8 associated PEL in late stages 


● Extranodal sites: Liver, extranodal sites, CNS, 

bone marrow; less common: lung, skin, testis, 

heart, breast, GIT 

● More lymph node involvement since cART 


● Lymphomas preceded by 

hypergammaglobulinemia and persistent 

generalized LAD, although mostly present in 

advanced clinical stage with markedly elevated 

LDH 

● High serum IL-6 and IL-10 with EBV or HHV8 

Lymphomas occurring more specifically in HIVpositive 

patients 

Priya Skaria 


● PEL, plasmablastic lymphoma, and HHV8-positive 

DLBCL, NOS, occur more specifically in HIVpositive 

patients 

Lymphomas also occurring in immunocompetent 

patients 

● Burkitt lymphoma: GIT most common, BM 

(unusual but common in HIV), blood 

● DLBCL: extranodal or disseminated (CNS, GIT, BM, 

liver), stage III or IV disease, nodal less common, 

unusual sites (heart or anorectal region) 

● Primary CNS lymphoma: intracranial 

parenchymal tumors, basal ganglia, brain stem, 

meninges, may be deep-seated or multifocal 

● Plasmablastic lymphoma of the oral cavity or jaw; 

usually present in advanced clinical stage with B 

symptoms and BM involvement; others: GIT, skin, 

abdomen, retroperitoneum, soft tissue of the 

extremities, advanced clinical stage with B 

symptoms and BM involvement 

● CHL: Atypical clinical presentation with advancedstage 

BM or liver involvement, as well as noncontiguous 

spread to multiple nodal groups 

● Marginal zone lymphoma and lymphoma of 

mucosa-associated lymphoid tissue have been 

described in children and adults 

● Increased risk of lymphoplasmacytic lymphoma 

and lymphoblastic leukemia 

● Rare NK/T-cell lymphomas: including mycosis 

fungoides, anaplastic large cell lymphoma, and 

nasal type NK/T-cell lymphoma 

Lymphomas occurring in other immunodeficient 

states 

● Polymorphic lymphoid proliferations: Adults and 

children, lymph nodes and extranodal sites, 

conform to the criteria or polymorphic PTLD 


Microscopy 

● Burkitt lymphoma: greater variation in cell size 

and shape (Fig: 1) than the typical intermediate 

sized cells, characteristic plasmacytoid 

differentiation which is peculiar to patients with 

AIDS 


Figure 1 

● DLBCL: rich in centroblasts or immunoblasts 

● Primary CNS lymphoma: immunoblastic type, 

tend to follow vascular channels as perivascular 

cuffs, and there may be admixed small 

lymphocytes and glial cells 

● Plasmablastic lymphoma: sheet-like proliferation 

of large cells with immunoblastic or plasmablastic 

appearance; more centroblastic with 

plasmablastic phenotype in the oral cavity 

● CHL: Before cART, mixed-cellularity, or 

lymphocyte-depleted subtypes. Likely due to 

improved immunity with anti-HIV therapy, 

nodular sclerosis CHL now accounts for nearly half 

of cases 

● Polymorphic lymphoid proliferation: Range of 

lymphoid cells, from small cells (often with 

plasmacytoid features) to immunoblasts, with 

scattered large bizarre cells 


● Burkitt lymphoma: CD10+ (Fig: 2), BCL2-, LMP1-, 

subset EBV+ 

● DLBCL: more germinal center B-cell type, subset 

EBV+, EBV with MYC expression impaired survival 

● Plasmablastic lymphoma: weakly positive for 

CD45 and usually negative for B-cell markers, 

including CD19, CD20, and PAX5, but most cases 

are positive for CD79a, IRF4/MUM1, 

PRDM1/BLIMP1, CD38, and CD138, 

Intracytoplasmic IgG +/-, aberrant CD2, CD4, Ki67 

100%, majority positive for EBV in the absence of 

EBNA2, LMP1 -, LMP III+/- 

● CHL: Majority EBV+ with type II latency pattern 

(EBNA1, LMP1, and LMP2), decreased nodal CD4+ 

T-cells and lack of CD4+ rosetting around 

Hodgkin/Reed-Sternberg cells 

● Polymorphic lymphoid proliferations: Large 

bizarre cells positive for CD30, EBV often present 

but some cases are EBV negative 

GENETICS 

● Consistently monoclonal lymphomas 

● Fewer polyclonal and oligoclonal lymphoid 


● Abnormalities of MYC, BCL6 and tumor 

suppressor genes 

● DLBCL: Most have IG heavy and light chain gene 

rearrangements, and several proto-oncogenes 

may be involved in the pathogenesis, including 

MYC, BCL2, and BCL6. EBV infection is associated 

with the expression of several tumor markers that 

are involved in the NF-kappaB pathway 

● Plasmablastic lymphoma: MYC translocation or 

amplification, no translocations involving BCL2, 

BCL6, MALT1 or PAX5 

● Polymorphic B-cell proliferation: Clonal B-cell 

population in an oligoclonal background, clonal 

EBV infection, lack structural alterations in MYC, 

BCL6, the RAS family of genes and TP53 

Figure 2 


Prognosis 

● Achievement of complete remission is the most 

important prognostic factor 

● MYC in DLBCL: increased 2-year mortality 


● Infiltrating CD8+ T-cells may be associated with 

reduced mortality from lymphoma 

● Plasmablastic lymphoma: early relapses, and 

chemotherapy resistance with an inferior overall 

survival compared with DLBCL and Burkitt 

lymphoma 

● In Burkitt lymphoma, the use of modified 

CODOX-M (cyclophosphamide, vincristine, 

doxorubicin, and high-dose methotrexate) 

regimens equals survival to that of HIV negative 

patients 

● PEL: usually very poor prognosis 

Treatment 

● HIV-directed therapy can now reduce the impact 

of HIV-related prognostic factors and allow 

curative therapy for most patients with aggressive 

lymphoma 

● Supportive care and coincident cART 

● CHL should be treated with curative intent 


Chapter 21: Histiocytic and dendritic cell neoplasms 

Vanya Jaitly Akanksha Gupta 

HISTIOCYTIC SARCOMA 

INTRODUCTION 

● Malignant proliferation of cells of histiocytic 

lineage 

● Malignant histiocytosis is the term used to 

describe the involvement of multiple systemic 

sites 

● Synchronous or sequential occurrence of these 

tumors have been described with small B-cell 

lymphomas and germ cell tumors 

Demographics 


● Extranodal involvement of GI tract, soft tissue, 

and skin more common than nodal involvement 

● Liver, spleen, and bone marrow may be involved 


● Constitutional symptoms: fever & weight loss 

● GI tumors present with obstruction 

● Skin involvement occurs in the form of rash or 

solitary to multiple tumors 


Lymph Node 

● Background is polymorphic with proliferation of 

reactive neutrophils, lymphocytes, plasma cells, 

and small lymphocytes 

Figure 2 

● CNS histiocytic sarcomas show exuberant 

neutrophilic infiltrate 


● Histiocytic markers (CD68, CD163, and lysozyme) 

positive 

● CD45, CD45RO, HLA-DR, and CD4 positive 

● Negative for B-cell, T-cell, epithelial and 

melanocytic markers 

CD68 

CD163 

Figure 1 

● Diffuse effacement of nodal or extranodal 

architecture by tumor cells 

● Cells are large, non-cohesive with abundant 

eosinophilic cytoplasm and eccentrically placed 

large nuclei 

● Hemophagocytosis, xanthomatous change and 

sarcomatoid areas may be seen 

Figure 3 

GENETICS 

● Cases considered to be examples of transdifferentiation 

show rearrangements or 

translocations of the associated entity 

[monoclonal IG rearrangement, t(14;18)] 

● BRAF V600E mutations have been described 


Prognosis 


● Aggressive neoplasms with poor response to 

treatment 

● Small tumors and localized disease are associated 

with better prognosis 

TUMORS DERIVED FROM LANGERHANS CELLS 

Tumors derived from 

Langerhans cells 

Langerhans Cell 

Histiocytosis 

Langerhans Cell 

Sarcoma 

LANGERHANS CELL HISTIOCYTOSIS 

INTRODUCTION 

● Malignant proliferation of Langerhans cells with 

distinctive cytologic, immunohistochemical and 

ultrastructural features 

● Subset of cases are associated with T- ALL with 

similar TR gene rearrangement suggesting 

transdifferentiation of lymphoid cells into LCH 

cells 

Demographics 

● Peak in the pediatric population 

● Male preponderance 

● Single system involvement common in adults 

● Multisystem involvement common in infants 


● Unifocal, unisystemic, multifocal or multisystemic 

involvement 

● Bone, lymph node, skin, and lung are commonly 

involved as a solitary lesion 

● Multisystemic disease commonly involves skin, 

bone, liver, and spleen 


● Unifocal: lytic bone lesion, lymphadenopathy, 

mass lesion 

● Multifocal: multiple osteolytic lesions involving 

skull bones, pituitary dysfunction 

● Multisystemic: Constitutional symptoms like 

fever, cytopenias, hepatosplenomegaly 



● Medium-sized oval cells with irregular grooved 

nuclei, inconspicuous nucleoli, and abundant pale, 

eosinophilic cytoplasm 

● Characteristic background population of 

eosinophils, neutrophils, small lymphocytes, and 

osteoclast type giant cells 

Figure 4 

Figure 5 

Figure 6 


● Monoclonal B- and T-cell gene rearrangements 

● BRAF V600E mutation and MAP2K1 mutations 

common 

PROGNOSIS 

● Multisystem and multifocal disease, lung, liver, 

and bone marrow involvement are factors 

associated with poorer prognosis 

Spleen 

● Red pulp involvement in spleen, sinusoidal and 

paracortical involvement in lymph node and 

biliary tract involvement in the liver is 

characteristic 

Electron microscopy 

● Presence of tennis racket-shaped Birbeck 

granules in the cytoplasm 


● Langerhans cell markers (CD1a, Langerin, and 

S100) positive 

● CD68, HLA-DR, and CD4 positive 

● Negative for B- cell, T- cell, epithelial, CD30 and 

follicular dendritic cell markers 

Figure 8 

Figure 7 

GENETICS 

● Majority of cases clonal on HUMARA gene assay 

LANGERHANS CELL SARCOMA 

INTRODUCTION 

● Malignant proliferation of Langerhans cells with 

nuclear pleomorphism exceeding that seen in 

Langerhans cell histiocytosis 

Demographics 

● Rare 

● Adults 


● Skin and soft tissue are the most common sites 

● Multisystemic disease commonly involves lymph 

node, lung, bone, liver, and spleen 


● Pancytopenia 


● Skin and soft tissue mass 



● Pleomorphic cells with clumped chromatin and 

conspicuous nucleoli 

● Occasional cells with nuclear grooves 

● High mitotic rate 

Electron microscopy 

● Presence of tennis racket-shaped Birbeck granules 

in the cytoplasm 


● Langerhans cell markers (CD1a, Langerin, and 

S100) positive 

● CD68, HLA-DR, and CD4 positive 

● Negative for B- cell, T- cell, epithelial, CD30 and 

follicular dendritic cell markers 

GENETICS: Occasional cases with BRAF mutations 


PROGNOSIS: Poor 

INDETERMINATE DENDRITIC CELL TUMOR 

INTRODUCTION 

● Extremely rare neoplasm of indeterminate cells 

● Indeterminate cells are postulated precursors of 



● Skin predominantly 

● Lymph node and spleen may be involved 


● Tumors on skin 

● No systemic symptoms 


Lymph Node 

● Diffuse effacement of dermis and subcutis by 

neoplastic cells resembling Langerhans cells 

● Cells have spindled to oval with nuclear grooves 

and eosinophilic cytoplasm 

● Multinucleated giant cells can be seen 

● Birbeck granules, a feature of Langerhans cells is 

lacking on electron microscopic examination 


● Positive: S100 and CD1a 

● Variable positive: CD45, CD68, lysozyme, and 

CD4 

● Negative: Langerin, B- cell, T- cell, dendritic cell 

markers (CD21, CD23, CD35), CD30, and CD163 

Demographics 

● Rare 

● Adult males 


● Nodal and extranodal sites including skin 

and soft tissue 


● Mass lesion 

● Systemic symptoms (fever, fatigue, night sweats) 

in a subset of cases 


Lymph Node 

Figure 9 

GENETICS 

● Limited data as this entity is extremely rare 

PROGNOSIS` 

● Variable 

● Prognostic factors are not known 

INTERDIGITATING DENDRITIC CELL SARCOMA 

INTRODUCTION 

● Neoplastic proliferation of spindle/ovoid cells of 

interdigitating dendritic cell lineage 

● Can occur in association with low-grade B-cell 

lymphomas (transdifferentiation) 

Figure 10 

● Ovoid to spindle cells forming whorls and 

storiform pattern mimicking follicular dendritic 

cell sarcoma 

● Cells have ovoid nuclei with indentations, 

vesicular chromatin, distinct nucleoli, eosinophilic 

cytoplasm, and indistinct cell borders 


● Tumor infiltrates the paracortex when involving 

lymph nodes 

● Mitotic rate is low 

● Multinucleated cells and lymphocytic infiltrate 

can be seen 


● S100, vimentin, fascin positive 

● Nuclear p53 positivity may be seen 

● Variable for CD68, lysozyme, and CD45 

● FDC markers (CD21, CD23, CD35) negative 

● Langerhans cell markers (langerin, CD1a) are 

negative 

● Background lymphocytes are T-cells 

Figure 11 

GENETICS 

● IG rearrangements are seen in cases arising as a 

result of trans-differentiation 

FOLLICULAR DENDRITIC CELL SARCOMA 

INTRODUCTION 

● This category comprises of neoplastic 

proliferation of ovoid cells of follicular dendritic 

cell lineage 

● The immunophenotypic profile supports FDC 

lineage 

● Inflammatory pseudotumor-like variant is a 

distinct variant of FDCS often arising in liver/ 

spleen and with a strong association to EBV 

Demographics 

● Rare; Adults, M=F 


● Lymph nodes, gastrointestinal tract, soft tissue, 

skin, mediastinum, retroperitoneum, lung 


● Mass lesion 

● Systemic symptoms occur rarely 

● Paraneoplastic pemphigus may occur 

● Inflammatory pseudotumor-like variant: 

‣ Young females, hepatosplenic, GI involvement 


● Oval to spindle cells forming diffuse sheets, 

nodules or storiform arrays 

● The cells are ovoid with oval nuclei, fine 

chromatin, distinct nucleoli, eosinophilic 

cytoplasm, and indistinct cell borders 

● Nuclear pseudoinclusions, multinucleated cells, 

and background lymphocytes are frequently seen 

● Mitotic rate is usually low but can be higher in 

pleomorphic cases 


‣ Scattered spindled neoplastic cells in an 

admixture of lymphocytes, plasma cells and 

histiocytes 

‣ Necrosis, hemorrhage, granulomas frequently 

seen 

‣ Fibrinoid necrosis of vessel walls 

‣ Variable nuclear atypia 

‣ Presence of RS-like tumor cells, abundant 

eosinophils in some cases may mimic CHL 

Figure 12 


Fig : CD23 

Fig : CD21 

Figure 13 

Picture credits: Pedro Alexio @PBAlexio 

Figure 15 

Picture credits: Siba El Hussein @SibaElHussein 

Figure 14 


● FDC markers positive (CD21, CD23, CD35) 

● CXCL13, D2-40, clusterin (specific) usually 

positive 

● Desmoplakin, vimentin, fascin, EGFR, and HLA-DR 

positive 

● FDC secreted protein, PD-L1, serglycin are 

positive 

● EMA, S100, and CD68 are variable 

● TdT positive background T-cells if present are 

associated with paraneoplastic pemphigus 

● EBER negative 


‣ FDC (CD21, CD23, CD35) or fibroblastic 

reticular cell (SMA) markers positive 

‣ EBER positive 

GENETICS 

● BRAF V600E mutations in a subset of cases 

● Loss of function mutations in tumor suppressor 

genes affecting cell cycle and NF kappaB pathway 



Prognosis 

● Large size (≥6 cm), coagulative necrosis, 

pleomorphism and increased mitotic rate (≥5/10 

HPF) are associated with poor prognosis 

● Local recurrence and distant metastasis can occur 


‣ Indolent 

‣ Local recurrences occur 

Treatment 

● Surgical excision 

● Adjuvant radiotherapy or chemotherapy given in 

some cases 

FIBROBLASTIC RETICULAR CELL TUMOR 

INTRODUCTION 

● Rare tumor which is similar to follicular dendritic 

cell sarcoma on histology, but with different 

immunohistochemical profile 



● Lymph node, spleen, soft tissue 


Lymph Node 

● Bland appearing spindle cells arranged in whorls 

with interspersed collagen fibers 


● SMA, desmin, cytokeratin and CD68 positive 

● Follicular and interdigitating cell markers are 

negative 

Figure 16 

GENETICS 

● Unknown as number of cases limited 

PROGNOSIS 

● Variable, not enough data 

DISSEMINATED JUVENILE XANTHOGRANULOMA 

INTRODUCTION 

● Rare benign systemic disorder with proliferation 

of foamy histiocytes as seen in benign cutaneous 

juvenile xanthogranuloma 

● Known association with neurofibromatosis type 1 

● Differential includes Erdheim-Chester disease 

Demographics 

● Affects pediatric population 


● Multisystemic involvement including skin, CNS, 

lung, GIT, liver, orbit, BM and lymph nodes 


● Varies based on site of involvement 

● CNS involvement presents with seizures, 

hydrocephalus, diabetes insipidus, and cognitive 

changes 

● Orbital involvement can cause glaucoma 

● Soft tissue lesions produce a mass effect 

● Macrophage activation syndrome can be present 

leading to death 


● Infiltration by cells which are oval to spindled with 

bland nuclei and vacuolated to pink cytoplasm 

● Cells are small without nuclear grooves 

● Background inflammatory cells are seen with or 

without Touton-type giant cells 


● Positive for monocytic/histiocytic markers (CD14, 

CD68, CD163, stabilin) 

● Positive for interstitial and interdigitating cell 

markers (factor XIII and fascin) 

● Negative for Langerhans cell markers (CD1a and 

langerin) 

GENETICS 

● Not consistent 

● Clonality is proven only in some cases 


Prognosis 

Figure 17 


● Benign disorder, but multisystemic involvement 

can be debilitating 

Treatment 

● LCH type therapy has been used for cases with 

hepatic and bone marrow 

ERDHEIM CHESTER DISEASE 

INTRODUCTION 

● Clonal systemic proliferation of histiocytes, 

commonly having a foamy component and 

Touton giant cells 

● Non-Langerhans cell multisystemic histiocytic 

neoplasm with variable manifestations 

● Subset of these patients are also afflicted by 


● Differential includes juvenile xanthogranuloma 

and Langerhans cell histiocytosis 

Demographics 

● Rare 

● Elderly affected more often than young 

● Male preponderance 


● Skeletal system, central nervous system, 

cardiovascular system, kidney, retroperitoneum 

and skin involved most commonly 


● Varies depending on the site of involvement 

● Bone pains with skeletal involvement 

● Cardiac involvement can cause pericardial 

effusion, cardiac tamponade, and hypertension 

● Orbital involvement can cause exophthalmos, 

blindness, and xanthelasma 

● CNS involvement can cause pituitary dysfunction, 

seizures, cranial nerve palsies, and 

neurodegenerative disorders 

Radiologic findings 

● Skeletal system: bilateral symmetric metaphyseal 

and diaphyseal sclerosis on X-ray and increased 

uptake on technetium-99m bone scintigraphy 

● Cardiovascular system: pericardial effusion, 

periaortic (coated aorta) and right atrial 

infiltration by tumor 

● Retroperitoneum: peri-renal infiltration by tumor 

giving rise to hairy kidney sign 


Extranodal sites 

● Architectural effacement by sheets of foamy 

histiocytes 

● Cells are large with foamy to eosinophilic 

cytoplasm and small nuclei 

● Touton giant cells and fibrosis are seen 

frequently 

● Background polymorphic with infiltrate of plasma 

cells, neutrophils, and small lymphocytes 

Figure 18 

Figure 19 


● Monocytic/ Histiocytic markers (CD14, CD68, and 

CD163) positive 

● Interstitial and interdigitating cell markers (factor 

XIIIa and fascin) are positive 


● VE1 positive in cases with mutated BRAF 

● Negative for Langerhans cell markers (S100, CD1a, 

and langerin) 

CD68 

S100 

GENETICS 

Figure 20 

● Mutations involving MAP kinase pathway genes 

(BRAF V600E and NRAS) and PIK3CA pathway genes 

have been described. 


Prognosis 

● Varies depending on site of involvement 

● CNS and multisystemic involvement are 

associated with poor prognosis 

Treatment 

● Interferon alpha and vemurafenib (BRAF inhibitor) 

have been used successfully 

● Cases with CNS and cardiovascular involvement 

are often nonresponsive to therapy 



In A Nutshell 



In a Nutshell: [A] B-cell Lymphomas 

Chronic lymphocytic leukemia/ 

small lymphocytic lymphoma (CLL/SLL) 

IN A NUTSHELL: MATURE B-CELL LYMPHOMAS 

Nidhi Kataria Akanksha Gupta 

• Adults leukemia/lymphoma presenting with lymphadenopathy, splenomegaly, and 

lymphocytosis 

• Diffuse architectural effacement by proliferation of small lymphocytes with variably 

prominent paler proliferation centers composed of prolymphocytes and paraimmunoblasts 

• Peripheral smear lymphocytosis composed of small mature lymphocytes with numerous 

smudge cells 

• Absolute lymphocyte count >5000/ul diagnostic of CLL 

• Bone marrow aspirate CLL cells >30% (most cases) 

• Positive for CD19, CD20 (dim), CD22, sIg (dim), CD79a, CD5, CD23, LEF1 (specific for CLL), 

CD200 

• Negative for CD10, FMC7, BCL6 

• del 13q14 (most common), trisomy 12, del 11q, and del 17p 

• Transformation of CLL into high-grade lymphoma (proliferation centers broader than a 20x 

field or confluent), Ki67 >40%, or >2.4 mitoses in the proliferation centers) 

• Richter syndrome (transformation to large cell lymphoma): DLBCL type and classic Hodgkin 

lymphoma type 

• Adverse prognostic factors: CD38 and/or ZAP70 expression implying unmutated IgVH status, 

del 11q, del 13p, high beta-2 microglobulin (>4), higher initial lymphocyte count (>30,000), 

lymphocyte doubling time 55%, medium-sized lymphoid cells with a round nucleus, moderately 

condensed nuclear chromatin, a prominent central nucleolus, and a small amount of faintly 

basophilic cytoplasm 

• Presents with high WBC >100,000/uL, B symptoms, splenomegaly, and absent or minimal 


• Immunophenotype differs from CLL/SLL with >80% cases negative for CD5 and CD23, bright 

sIg, bright CD200 and FMC7 positive 

• Responds to splenectomy, CHOP chemotherapy regimen, fludarabine, and cladribine and no 

response to CLL therapy 

Splenic marginal zone lymphoma (SMZL) • Involves spleen (mainly white pulp with infiltration into red pulp), splenic hilar lymph nodes 

(not other nodes), liver (sinusoids), bone marrow (nodular pattern) and peripheral blood 

(villous lymphocytes) 

• Neoplastic cells surround and replace the splenic white pulp germinal centers, efface the 

follicle mantle, and merge with a peripheral (marginal) zone of larger cells, and can also 

infiltrate the red pulp 

• Positive for CD20, CD79a, sIg (IgM and IgD), Ki67 (targetoid pattern) 

• Negative for CD5, CD10, CD23, CD43, annexin A1, CD103, cyclin D1 

• Show Ig genes rearrangement, mutation of NOTCH2, and KLF 2 (associated with del 7q). 

Lack translocation typical of other lymphoma like t(14;18), t(11;14); t(11;18) and t(1;14) 

• Indolent lymphoma that responds to splenectomy and/or rituximab 

• Hepatitis C virus positive cases respond to antiviral treatment using interferon-gamma, with 

or without ribavirin 

• Adverse prognostic factors: NOTCH2, KLF2, p53 mutation and large tumor mass 

Hairy cell leukemia (HCL) • Indolent neoplasm of small mature lymphoid cells with hairy projections involving peripheral 

blood, bone marrow, liver (sinusoids) and splenic red pulp (blood lakes) 

• Bone marrow fibrosis with a dry tap on aspiration and fried egg morphology on biopsy 

• Positive for CD20, CD22, CD11c, CD103, CD25 (bright), CD123, TBX21, annexin A1 (most 

specific), FMC7, CD200 and cyclinD1 (dim, nuclear) 

• Negative for CD5, CD23, and CD10 

• BRAF V600E mutation and TRAP-positive on cytochemistry 

• Treatment: interferon alfa or nucleosides; for relapse: rituximab, anti-CD22 agents or BRAF 

inhibitor 

Splenic B-cell lymphoma/ 

leukemia unclassifiable 

Splenic diffuse red 

pulp small B-cell 

lymphoma 

• Involves spleen (diffuse involvement of red pulp) causing massive splenomegaly, peripheral 

blood (villous lymphocytosis), bone marrow (intrasinusoidal) 




Hairy cell 

leukemia - variant 

• Positive for CD20, CD72 (DBA.44), IgG 

• Negative for IgD, Annexin A1, CD25, CD5, CD103, CD123, CD11c, CD10, CD23 

• Indolent, but incurable neoplasm, responds to splenectomy 

• Adverse prognostic factors: NOTCH1, MAP2K1, TP53 mutation 

• Involves peripheral blood, bone marrow (sinusoidal with no fibrosis) and spleen (diffuse red 

pulp, blood lakes), liver (portal and sinusoidal) 

• Lymphocytosis with cells with hairy projections (like HCL) but with prominent nucleoli 

(resembling prolymphocytes) 

• Positive for CD72, CD11c, CD103, IgG, FMC7, pan B-cell Ag 

• Negative for CD25, Annexin A1, TRAP, CD200, CD123 

• Negative for BRAF V600E mutation and TRAP negative on cytochemistry 

• Response to splenectomy, cladribine with rituximab (not cladribine alone as in HCL) 

Lymphoplasmacytic lymphoma (LPL) • Indolent neoplasm of small B-lymphocytes, plasmacytoid lymphocytes, plasma cells 

• Involves bone marrow (increased mast cells), lymph nodes (preserved architecture with PASpositive 

material in dilated sinusoids or effaced architecture with follicular growth), and some 

extranodal sites 

• Associated with Hepatitis C and cryoglobulinemia and presents with IgM paraproteinemia and 

hyperviscosity syndrome 

• Positive for sIg (IgM > IgG >>> IgA), B-cell antigens: CD19, CD20, CD22, CD79a 

• Negative for CD5, CD103, CD10, CD23 

• Plasma cell is positive for CD138, CD19, CD45, PAX5, Negative for MUM1 

• MYD88 L265P mutations (most common), CXCR4 truncating frameshift mutations, ARID1A 

mutations 

• Adverse prognostic factors: advanced patient age, cytopenia, high B2-microglobulin levels, 

serum paraprotein >7 g/dL, del 6q, absent MYD88 mutations (low response to ibrutinib) 

IgM MGUS • Serum IgM monoclonal protein concentration





variants 

Plasmacytoma 

IMWG diagnostic criteria: 


• Clonal bone marrow plasma cells >10% or biopsy proven plasmacytoma 

• Any one or more of the following myeloma defining events: 

• End organ damage attributable to plasma cell proliferative disorders 

‣ C: Hypercalcemia; Serum calcium >11mg/dL (2.75mmol/L) OR >1mg/dL 

(0.25mmol/L) higher than the upper limit of normal 

‣ R: Renal insufficiency; Creatinine clearance 2mg/dL 

(177umol/L) 

‣ A: Anemia, Hb2g/dL below the lower limit of normal 

‣ B: Bone lesions >1 osteolytic lesion on skeletal radiography, CT or PET/CT 

• Clonal plasma cell proliferation >60% 

• Involved: uninvolved serum free light chain (FLC) ratio >100 (involved FLC must be 

>100mg/L) 

• >1 focal lesion on MRI (at least 5 mm in size) 

Neoplastic plasma cells: 

• Express monotypic cytoplasmic lg and lack surface lg 

• Express CD38 and CD138; CD38 dimmer and CD138 brighter than in normal plasma cells 

• CD45 is negative or expressed at low levels; CD19 is negative in 95% of cases, and 

• Dim or negative CD27 and CD81 

• Aberrant expression of antigens like CD56, CD20, CD28, KIT, CD52, CD10, and occasionally 

myeloid and monocytic antigens, and stem cell-associated antigens 

• May show increased expression of MYC, cyclin D1 {in cases with t(11;14) (IGH/CCND1) and 

cases with hyperdiploidy} 

• International Staging system (ISS) classifies myeloma into 3 stages based on the serum beta- 

2 microglobulin level and serum albumin level, with stage III having lowest survival 

• Mayo Stratification of Myeloma and Risk-Adapted Therapy (R-ISS) classifies myeloma into 

• Standard risk (t(6;14), t(11;14); hyperdiploid); Intermediate risk (t(4;14), del13, hypodiploid) 

• High risk (del17p, t(14;16), t(14;20) and high risk gene signature) 

Smoldering 

(asymptomatic) 

Non-secretory 

Myeloma 

Plasma cell 

Leukemia (PCL) 

Solitary 

plasmacytoma of 

bone 

Smoldering plasma cell myeloma (SPCM) 


• Serum monoclonal protein (IgG or IgA) ≥30g/L or Urinary 

monoclonal protein ≥500mg per 24h and/or clonal bone marrow 

plasma cells 10-60% 

• Absence of myeloma-defining events, i.e. (CRAB) and amyloidosis 

Light chain SPCM 

• Urinary Light chain M protein ≥0.5g/24 hours 

• Percentage of plasma cells in bone marrow: 10-60% 

• Absence of end-organ damage attributable to the plasma cell 

disorder 

• Absence of an M protein by serum and urine immunofixation 

electrophoresis 

• Minimally secretory or oligo-secretory 

• Non-producer myeloma: no cytoplasmic lg synthesis is detected 

• Clonal plasma cells > 20% of total leukocytes in the blood or the 

absolute count >2.0 x 10 9 /L 

• A higher proportion of cases of the light chain- only, lgE, and lgD 

myelomas present as PCL compared with lgG or IgA myelomas 

• PCL differs from other PCMs by its more frequent expression of 

CD20 and less frequent expression of CD56 (negative in 80% cases) 

• Aggressive disease with poor response to therapy 

• Biopsy-proven solitary lesion of bone or soft tissue consisting of 

clonal plasma cells 

• Normal random bone marrow biopsy with no evidence of clonal 

plasma cells 

• Normal skeletal survey and MRI or CT (except for the primary 

solitary lesion) 




• Absence of end-organ damage such as CRAB or amyloidosis 

attributable to a plasma cell proliferative disorder 

Monoclonal 

immunoglobulin 

deposition disease 

Extraosseous 

plasmacytoma 

Primary 

amyloidosis 

Systemic light and 

heavy chain 

deposition disease 

Solitary plasmacytoma with minimal marrow involvement 

• Same as above, plus 

• Clonal plasma cells lambda) 

‣ Heavy chain deposition disease (HCDD) (gamma> alpha) 

‣ Light and heavy chain deposition disease (LHCDD) 

• Electron microscopy: Non-fibrillary powdery electron-dense deposits 

• X-ray diffraction: Absence of beta-pleated sheets 

PCN with associated 

paraneoplastic 

syndromes 

POEMS syndrome • Mandatory criteria 

‣ Polyneuropathy 

‣ Monoclonal plasma cell proliferative disorder 

• Major criteria (≥1 required) 

‣ Castleman disease 

‣ Osteosclerotic bone lesion 

‣ VEGF elevation 

• Minor criteria (≥1 required) 

‣ Organomegaly 

‣ Endocrinopathy 

‣ Skin changes 

‣ Papilledema 

‣ Thrombocytosis 

‣ Extravascular volume overload 

TEMPI syndrome • Telangiectasia 

• Elevated erythropoietin and erythrocytosis 

• Monoclonal gammopathy (IgG kappa) 

• Perinephric fluid collection 

• Intrapulmonary shunting 

• VEGF levels: normal 

• Responds to Bortezomib 




Extranodal MALT lymphoma ● Neoplastic cells in the marginal zone extend into interfollicular and follicular areas 

● Cells include marginal zone centrocyte-like cells, monocytic cells, small B lymphocytes, and 

few immunoblasts and centroblast-like cells 

● Lymphoepithelial lesions are formed in epithelial tissues 

● Associated with chronic antigenic stimulation: infection or autoimmunity; most commonly 

involve stomach 

● Positive for IgM heavy chains, B-cell markers with light chain restriction, IRTA1, MNDA 

● Negative for CD5, CD10, CD23, BCL6 


● H. pylori antibiotic therapy leads to remission in gastric MALT lymphoma 

● t(11;18)( q21;q21): resistant to H. pylori eradication therapy 

● Translocations (related to upregulation of NFkB: t(1;14), t(11;18), t(14;18), t(3;14) 

Nodal marginal zone lymphoma • Marginal zone lymphoma in the lymph node that morphologically resembles extranodal or 

splenic type; but no extranodal or splenic disease 

• Associated with autoimmune disease, HCV infections 

• Proliferation of neoplastic cells around the follicles and in interfollicular areas 

• Positive for pan-B cell markers, CD43, BCL2, MNDA, IRTA1 

• Negative for CD5, CD23, cyclin D1, germinal center markers as CD10, BCL6, HGAL, LMO2 

• Good prognosis in general 

• Worse prognosis: advanced age, B symptoms, advanced disease stage 

Follicular lymphoma Follicular lymphoma • Isolated lymphadenopathy without constitutional symptoms, involving bone marrow in 30% of 

cases at presentation 

• Nodular lymphoid proliferation that typically overruns the lymph node capsule 

• Back to back or fused follicles with attenuated mantles, loss of polarity, absence of tingible 

body macrophages and diminished mitosis 

• Two cell types in varying proportions: small cleaved cells (centrocytes) and large noncleaved 

cells (centroblasts) 

• Grading is based on the proportion of large noncleaved cells (centroblasts) in 40x fields of 10 

randomly selected neoplastic follicles 

• Grades based on centroblasts/ 40x field: 1: 0-5; 2: 6-15; 3: >15 (3a: some residual centrocytes, 

3B: no residual centrocytes) 

• Positive for surface Ig (IgM, IgG), B-cell markers, germinal center markers: LMO2, GCET1, HGAL 

(GCET2), BCL2, BCL6, CD10 

• BCL2 expression in follicles: Hallmark of FL and will aid to differentiate reactive follicles vs. FL 

• CD21, CD23 highlight FDC within the follicles 

• Ki67 in grade 1-2 is 20% 

FL variants Diffuse variant FL • Inguinal lymph nodes involvement showing microfollicles with weak-absent BCL2 stain 

• Positive for CD10, CD23 

• Absent t(14;18) IGH/BCL2 

• Shows del 1p36, containing gene TNFRSF14 

Testicular FL • High-grade FL with good prognosis occurring mainly in children and lacking BCL2 translocation 

In situ 

follicular 

neoplasia 

Duodenal 

type follicular lymphoma 

• Intact nodal architecture with widely scattered involved follicles 

• Architecturally reactive appearing germinal centers with cytologic features of FL (infiltrate 

composed exclusively of centrocytes, demonstrated by strong immunostaining for CD10 and 

BCL2 

• Multiple small polyps in the second part of the duodenum detected incidentally on endoscopy 

• Neoplastic follicles (composed of centrocytes) in the mucosa/submucosa 

• Low rate of lymph node dissemination with an excellent prognosis 

• Positive for CD20, CD10, and BCL2; CD21 restricted to the periphery of the follicle 

• Negative for activation-induced cytidine deaminase 

Pediatric-type follicular lymphoma • Localized nodal enlargement occurring primarily in children and young adults and sporadically 

in older individuals and predominantly affecting males 

• At least partial effacement of nodal architecture with pure follicular proliferation 

• Positive for BCL6, high Ki67 >30% and lacks BCL2, BCL6, IRF4 or aberrant IgG rearrangement 

• MAP2K1 mutations and del 1p36 containing gene TNFRSF14 

• Excellent prognosis 



Large B-cell lymphoma with IRF4 

rearrangement 

Primary cutaneous follicle center 

lymphoma 


• Diffuse, follicular and diffuse, or entirely follicular growth pattern 

• Occurring primarily in children and young adults, involving Waldeyer’s ring or head and neck 

lymph nodes 

• Positive for B-cell markers, MUM1, BCL6, (CD10 and BCL2 in 66% cases) 

• Strong expression of IRF4/MUM1, usually with IRF4 rearrangement, with/without BCL6 

rearrangement 

• Favorable prognosis after treatment 

• Tumor of neoplastic follicle center cells, including centrocytes and variable numbers of 

centroblasts, with a follicular, follicular and diffuse, or diffuse growth pattern 

• Solitary or localized skin lesions on the scalp, forehead, or trunk 

• Firm erythematous to violaceous plaques, nodules, or tumors of variable size, no ulceration 

• Perivascular and periadnexal to diffuse infiltrates, with sparing of the epidermis 

• Positive for CD20, CD79a, BCL6, variable CD10 (positive in follicular growth pattern and 

negative in diffuse) 

• Negative for BCL2, IRF4/MUM1, FOXP1, CD5, and CD43 

• Low rate of lymph node involvement and an excellent overall prognosis 

Mantle cell lymphoma • Aggressive neoplasm of small and medium sized monomorphic cells with CCND1 translocation 

in most cases 

• Involves lymph nodes, spleen and bone marrow, with or without peripheral blood, extranodal 

sites [Waldeyer’s ring, lungs, GIT (as multiple lymphomatoid polyposis)] 

• Variants: Aggressive (blastoid, pleomorphic); Indolent (small cell and marginal zone-like) 

• Positive for surface lgM/lgD (bright), lambda > kappa, cyclin D1, SOX11, CD5, FMC7, CD43, 

BCL2 

• Negative for CD10, BCL6, CD23 

• t(11;14) (q13;q32); (IGH; CCND1): overexpressing cyclinD1; abnormal SOX11 expression 

• Adverse prognostic factors: brisk mitoses, Ki67 >30%, blastoid/pleomorphic morphology, 

leukemia with adenopathy, complex karyotype, TP53 alteration, CDKN2A deletion 

• Leukemic non-nodal mantle cell lymphoma (LNN-MCL): Small cells resembling CLL cells, 

involving blood + bone marrow ± spleen, without significant adenopathy; better prognosis 

than classic mantle cell lymphoma 

• In-situ mantle cell neoplasia: Atypical lymphoid cells occupying only the inner mantle zone of 

a reactive follicle and showing positivity for cyclin D1 with CCND1 rearrangement 

Diffuse large B-cell lymphoma, not otherwise 

specified 

(DLBCL, NOS) 

T-cell/histiocyte rich large B 

Cell lymphoma (THRLBCL) 

• Diffuse proliferation of lymphoid cells of medium or large B lymphoid cells with nuclei the 

same size or larger than those of normal macrophages, or more than twice the size of 

lymphocytes 

• Rapidly enlarging, localized, nodal or extranodal mass; with B symptoms in one third patients 

• Morphology: centroblastic, immunoblastic (>90% immunoblasts) or anaplastic 

• Positive for CD19, CD20, CD22 and CD45, usually positive for BCL2 with variable expression of 

CD10, CD5, and BCL6 

• CD5+ DLBCL distinguished from blastoid MCL by lack of CCND1 rearrangement and cyclin D1 

overexpression 

• Germinal center B-cell (GCB) phenotype vs. activated (ABC) phenotype (Hans algorithm) 

• Morphologically, GCB is more likely to have centroblastic morphology, while ABC often has 

immunoblastic morphology 

• BCL2, t(14;18) rearrangement is common in GCB 

• BCL6, t(3;X) rearrangement is more common in the ABC type 

• Stepwise evaluation of DLBCL subtypes by immunohistochemistry (Hans method) 

‣ Step 1: If CD10+ in >30% of cells, then GCB; if CD10-, then proceed to step 2 

‣ Step 2: If BCL6- then non-GC (ABC); if BCL6+, proceed to step 3 

‣ Step 3: If MUM1+, then non-GC (ABC); If MUM1- then GCB 

• Double expressors (+ IHC for both MYC and BCL2) vs. double hit/ triple hit lymphoma (MYC + 

BCL2 and/or BCL6 rearrangements) 

• Positivity criteria: CD10, BCL6 and IRF4/MUM1 ≥ 30%; BCL2 ≥50%, and MYC ≥ 40% 

• Special subtypes: primary breast DLBCL, primary gastric DLBCL, primary testicular DLBCL 

• Involves lymph nodes (diffuse or vaguely nodular), liver (portal tract), spleen (white pulp) and 

presents as systemic disease 

• Scattered, large B-cells in the background of abundant T-cells and histiocytes 




• Absent follicular dendritic cells meshwork 

• Origin: de novo or progression from nodular lymphocyte predominant Hodgkin lymphoma 

(NLPHL) 

• Neoplastic cells are positive for pan-B markers and BCL6 

• Negative for CD15, CD30, or CD138 

• Background consists of CD68+ and CD163+ histiocytes and CD3+ and CD5+ T-cells 

Primary diffuse large B-cell lymphoma of CNS • DLBCL arising within the brain, spinal cord, leptomeninges or eye 

• No association with viruses like EBV, HHV6, HHV8, polyomaviruses SV40 and BK virus 

• Central large areas of geographical necrosis with perivascular lymphoma islands at the 

periphery 

• Positive for B-cells markers, sIg (lgM and lgD), IRF4/MUM1, BCL6, BCL2, high Ki67 >70% 

• Negative for plasma cell markers, CD10 (positivity should prompt search for systemic DLBCL) 

• Loss of major histocompatibility complex (MHC) class I and/or II expression 

• Adverse prognostic factors: del 6q, age >65 years 

Primary cutaneous large B-cell 

lymphoma, leg type 

• DLBCL arising in cutaneous locations, mostly in the lower legs and predominantly affecting 

elderly women 

• Non-epidermotropic infiltrate of large B-cells in the dermis 

• Positive for pan-B-cell markers, BCL2, IRF4/MUM1, FOXP1, MYC, BCL6, IgM and high Ki67 

• MYD88 L265P mutations, CDKN2A loss, and multiple skin tumors are poor prognostic factors 

• Treatment: RCHOP (rituximab, cyclophosphamide, doxorubicin, oncovin, prednisone) 

EBV-positive DLBCL (NOS) • EBV-positive large B-cell neoplasm that does not fit into other well defined EBV-positive 

entities predominantly affecting elderly Asian population 

• Aging-associated immune dysregulation plays a role in the development 

• Spectrum of morphology varying from polymorphic to monomorphic 

• Positive for B-cell markers, IRF4/MUM1, CD30, CD15, EBER, EBV type III or II latency pattern 

• Good prognosis: Younger patients, polymorphic pattern 

• Poor prognosis: CD30 positivity, EBNA2 positivity, old age and presence of B symptoms 

EBV-positive mucocutaneous ulcer • Ulcerated lesions with adjacent pseudoepitheliomatous hyperplasia in oral cavities, GIT of 

elderly or immunosuppressed 

• Reactive lymphadenopathy 

• Neoplastic cells have activated B-cell phenotype (IRF4/MUM1 positive), are positive for EBV 

markers: LMP-1, EBER; CD30 +, CD15 + in few cases 

• Background scattered lymphocytes are CD8+ T lymphocytes 

• Rim of CD3+ T-cells at the junction of the lesion and normal tissue 

• Indolent course and responds well to rituximab, local radiation, and chemotherapy 

DLBCL associated 

with chronic 

inflammation 

DLBCL associated with 


• EBV-associated large B-cell lymphoma arising at sites of long-standing chronic inflammation 

and most commonly involving body cavities and narrow spaces 

• Pyothorax associated lymphoma being the prototype; Males, twin peaks of age 

• Positive for B-cell markers, CD30 +/-, EBER, type III EBV latency 

• Aggressive course and poor prognostic factors: Elevated LDH, ALT 

• Treatment: Pleuro-pneumonectomy 

Fibrin associated DLBCL • Non mass forming lesion with favorable prognosis detected incidentally in specimens with 

fibrinous material 

• Floating within fibrinous material are aggregates of neoplastic cells 

• Activated B-cell phenotype, EBV positive: type III latency 

Lymphomatoid granulomatosis • EBV+ neoplastic B-cells that are angiocentric and angio-destructive; commonly affect western 

adult males 

• Large number of reactive CD3+ T-cells 

• Most commonly involve lungs, can also involve the brain, kidney, and subcutaneous tissue 

• Positive for B-cell markers, CD30, EBV markers: LMP-1, EBNA2, latency type III 

• Aggressive behavior with grading based on the number of EBV+ cells 

Primary mediastinal (thymic) large B-cell 

lymphoma 

• Large B-cell lymphoma arising in the anterosuperior mediastinum with distinct clinical, 

immunophenotypic, genotypic and molecular features mostly affecting young adult females 

• Involves anterosuperior mediastinum (thymus) and regional lymph nodes, producing superior 

vena cava syndrome 

• Interstitial fibrosis surrounds nodules of tumor cells 




• Positive for pan B-cell markers, B-cell transcription factors, CD30, IRF4/ MUM1, CD23, MAL1, 

PDL1/2, CD54, FAS/ CD95, TRAF, REL1, TNFAIP2 

• Variable expression of CD15, BCL2, BCL6, MYC 

• Negative for EBER, CD10, CD5, and sIg 

• Gain of 9p24.1 (PDL locus), 2p16.1 

• Mutations in TNFAIP3 (activation of NF-kappa B pathway), SOCS1, STAT6 and PTPN1 (activated 

JAK/STAT pathway), CIITA (downregulation of MHC class II), BCL6 

• Poor prognosis: extension into thoracic viscera, pleural/pericardial effusion and poor 

performance status 

Intravascular large B-cell lymphoma • Aggressive lymphoma involving extranodal sites with the growth of neoplastic cells within the 

lumen of vessels, small and intermediate-sized vessels 

• Positive for B-cell antigens 

• Patterns of presentation: classic, hemophagocytic associated and isolated cutaneous 

• Complications: CNS relapses and neurolymphomatosis 

ALK-positive large B-cell lymphoma 

(ALK+ LBCL) 

• Aggressive ALK+ LBCL with plasmablastic/ immunoblastic phenotype 

• Positive for ALK (cytoplasmic granular staining), B-cell transcription factors (OCT2, BOB1+), 

EMA, MUM1, plasma cell markers (CD138) 

• Negative for B-cell lineage markers, CD30 

• Not associated with immunosuppression (HIV, EBV, HHV8) 

• Molecular t(2;17) (ALK; CLTC) 

• Does not respond to standard therapy 

Plasmablastic lymphoma • Diffuse proliferation of large neoplastic cells, resembling B immunoblasts or plasmablasts, that 

have CD20-negative plasmacytic phenotype 

• Occurs in adults in association with immunodeficiency and have a poor prognosis 

• Involves extranodal regions of head and neck (oral cavity) and gastrointestinal tract 

• Positive for plasma cell markers (CD38, CD138, VS38c, IRF4/MUM1, PRDM1, XBP1), 

cytoplasmic Ig (IgG) with light chain restriction, EMA, CD30, CD56 (some cases), high Ki67 

>90%, EBER ISH 

• Negative for CD45, B-cell markers, HHV8 

Primary effusion lymphoma • Large B-cell neoplasm strongly associated with the HHV8, occurring in immunodeficient 

individuals, and has an extremely unfavorable prognosis 

• Presents as serous effusions without detectable tumor masses 

• Effusion contain large cells with immunoblastic, plasmablastic or anaplastic morphology 

• Extracavitary PEL: Rare HHV8-positive lymphomas presenting as solid tumor masses and 

occurring in lymph nodes or extranodal sites such as GIT, skin, lungs, and CNS 

• Positive for CD45, HLA-DR, CD30, CD38, VS38c, CD138, and EMA, HHV8-associated latent 

protein LANA1 (also called ORF73) (nuclear positivity), EBV (except non-HIV infected 

population) 

• Negative for B-cell markers, BCL6 

HHV-8-associated 


disorders 

HHV-8 positive 

Multicentric 

Castleman 

Disease 

HHV-8 positive DLBCL, 

NOS 

• Systemic polyclonal lymphoproliferative disorders with proliferation of benign cells due to 

increased cytokine production (IL6), occurring in association with HIV/AIDS 

• Presents with constitutional symptoms, splenomegaly, and generalized lymphadenopathy 

• Abnormal follicles with hypervascular or regressed germinal center, plasmablasts in mantle 

zone, and interfollicular plasma cell hyperplasia 

• Positive for HHV8 LANA1, cyIgM with chain restriction, viral IL6; Negative for EBER 

• Poor prognosis; Treatment: Rituximab + anti-herpes therapy + targeted therapy against IL6 

• Aggressive disease arising in the setting of MCD associated with HIV infection, EBV-negative 

• Lymph node and spleen: Effaced architecture by plasmablasts 

• Positive for HHV8 LANA1, cyIgM with chain restriction 

HHV-8 positive 

germinotropic 


disorder 

• Monotypic HHV8 disorder occurring in HIV negative patients, but associated with EBV 

infection 

• Preserved lymph node architecture, germinal centers replaced by HHV8+ plasmablasts 

• Negative for CD20, CD79a, CD138, BCL6, CD10 

• Positive for HHV8 LANA1 and EBER and exhibit light chain restriction 

• Favorable prognosis 




Burkitt lymphoma/leukemia • Aggressive but curable lymphoma that presents in extranodal sites or as an acute leukemia 

• Characterized by monomorphic medium-sized B-cells with basophilic cytoplasm and numerous 

mitotic figures, with a MYC gene translocation to an IG locus 

• Tingible body macrophages impart starry-sky appearance 

• Three clinicopathological types: Endemic, Sporadic and Immunodeficiency-associated 

‣ African (endemic): jaw mass in childhood and strong association with EBV 

‣ Western (sporadic): nodal or extranodal (abdominal) of young adults; not associated 

with EBV 

‣ Immunodeficiency associated BL: often HIV associated 

• Positive for CD19, CD20, CD22, CD10, BCl6, sIg (light chain restriction) and MYC with high Ki67, 

approximately 100% 

• Negative for CD5, CD23, BCL2, TdT, CD34 

• Poor prognostic factors: Advanced stage disease, bone marrow, and CNS involvement, 

unresected tumor >10 cm in diameter, and high serum lactate dehydrogenase level 

• Positive for MYC gene rearrangement as a result of MYC/IgH fusion t(8;14); also rearranged 

with IgK (2p12) or Igλ (22q11) 

Burkitt-like lymphoma with 11q 

aberration 

High-grade B-cell 

lymphoma (HGBL) 

(between DLBCL, 

NOS, and BL) 

HGBL with MYC 

and BCL2 and/or 

BCL6 


• Resemble Burkitt lymphoma (BL) morphologically and phenotypically but lack MYC 


• Show chromosome 11q alteration 

• Lack 1q gain frequently seen in BL 

• Aggressive lymphoma harboring rearrangement of MYC (8q24) and BCL2 (18q21) and/or BCL6 

(3q27); (except for proven follicular lymphomas and B lymphoblastic leukemia/ lymphomas) 

• Double hit lymphomas: MYC + BCL2 or BCL6 translocations 

• Triple hit lymphomas: MYC + BCL2 + BCL6 translocations 

• Rearrangement of MYC, BCL2, and BCL6 detected by cytogenetic/molecular method like FISH 

• Can resemble DLBCL, NOS or BL or intermediate between DLBCL and BL or have blastoid 

appearance mimicking lymphoblastic lymphoma or blastoid variant of mantle cell lymphoma 

(negative for TdT and Cyclin D1) 

HGBL, NOS • Aggressive lymphomas that lack MYC plus BCL2 and/ or BCL6 rearrangements and do not fall 

into the category of DLBCL, NOS or BL 

B-cell lymphoma, unclassifiable, with features 

intermediate between DLBCL 

and classic Hodgkin lymphoma 

• Lymphomas with overlapping features between CHL and DLBCL, mainly primary mediastinal 

(thymic) large B-cell lymphoma (PMBL) 

• Mediastinal cases are referred as mediastinal gray-zone lymphoma (MGZL) and presents as 

bulky mediastinal masses leading to superior vena cava syndrome or respiratory distress 

• Non-mediastinal cases are referred to as gray-zone lymphoma (GZL) 

• Cases with CHL on morphology show preservation of the B-cell markers with strong and 

uniform positivity for CD20 and CD79a 

• Cases with PMBL on morphology show loss of B-cell antigens but positivity for CD30 and CD15 


In a Nutshell: [B] T-cell Lymphomas 


T- lymphoblastic leukemia/ 

lymphoma 

Early T-cell precursor 

lymphoblastic leukemia 

(ETP-ALL) 

IN A NUTSHELL: SELECTED T-CELL LYMPHOMAS 

• Adolescent males affected most commonly 

• Mediastinal mass 

• TdT+, cytoCD3+ (lineage specific), CD7+, CD4/CD8 double+ or - 

• Variable CD2, surface CD3, CD5, CD34, CD10, CD99, CD1a and CD45 

• TCR and IGH genes rearranged frequently 

• Translocations involving chr 7 (TCR) and chr 14 

• Activating mutations of NOTCH1 seen in half of the cases 

• Higher risk disease than B-ALL 

• Unique immunophenotype indicating early T-cell differentiation 

• CytoCD3+, CD7+, one or more myeloid or stem cell markers+ (CD34, CD117, HLA-DR, CD13, CD33, CD11b, 

CD65) 

• Negative for CD1a, CD8, CD5 (if CD5 is strong, termed as “near ETP ALL”) and MPO 

• Prognosis poorer than T-ALL 

T-cell prolymphocytic leukemia • Aggressive leukemia involving blood, bone marrow, liver, spleen 

• Positive for T-cell antigens (CD3, CD2, CD5, CD7), CD52, TCL1 

• CD4+ (most cases), CD8+ (few cases), CD4/CD8 double+ (approximately a quarter of cases) 

• Negative for TdT, CD1a 

• Inv(14)(q11q32) seen in the majority of cases 

T-cell large granular 

lymphocytic leukemia 

Chronic lymphoproliferative 

disorder of NK cells 

• Indolent T-cell neoplasm of cytotoxic T-lymphocytes associated with autoimmune diseases esp. 

rheumatoid arthritis 

• Persistent increase in large granular lymphocytes in the absence of an underlying cause is required for 

diagnosis (>6 months, 2-20 x 10 9 /L) 

• Neutropenia, anemia in peripheral blood 

• Positive for CD3, CD8, CD16, CD57, cytotoxic markers (TIA-1, granzyme B, granzyme M) and TCR αβ 

• Loss or dim expression of CD5, CD7 is common 

• Negative for CD56 

• Clonal TC receptor gene rearrangement 

• Indolent disorder but cases with STAT3 mutations are associated with treatment failure and more 

symptomatic disease 

• Cases with STAT5B mutations have a more aggressive course 

• Provisional entity 

• Rare indolent disorder with a persistent increase in NK cells in peripheral blood in the absence of an 

underlying cause (>6 months, >2 x 10 9 /L) 

• No association with EBV 

• Positive for cytoCD3(epsilon), CD16, CD56, KIR restriction and cytotoxic markers (TIA, granzyme B, 

granzyme M) 

Aggressive NK cell leukemia • Aggressive NK cell leukemia seen commonly in young Asians with a strong association to EBV infection 

• Similar immunophenotype as Extranodal NK/T-cell lymphoma but is frequently positive for CD16 

• Positive: CD2, cytoCD3 epsilon, CD16, CD56, cytotoxic markers 


• Poor prognosis with an aggressive course 

Adult T-cell leukemia/ 

lymphoma 

Extranodal NK/T-cell 

lymphoma, nasal type 

• T-cell neoplasm associated with HTLV-1 infection and endemic in southern Japan, Caribbean and parts of 

Africa 

• Characteristic flower cells (polylobated leukemic cells) seen in peripheral blood 

• Clinical variants: acute, lymphomatous, chronic and smoldering 

• Positive: CD4, CD2, CD3, CD5, CD25 

• Negative: CD7, CD8 

• Clonal rearrangement of TCR 

• Aggressive lymphoma arising most commonly in nasal sites, strongly associated with EBV infection with 

an angiocentric and angiodestructive pattern 

• Asians and indigenous populations of Mexico, South and Central America affected commonly 

• Positive for NK cell (CD56+, surface CD3-) or T-cell (CD56-, CD3+) markers, cytoCD3-Epsilon, cytotoxic 

markers+ (perforin, TIA-1, and granzyme B), EBV, CD45, CD43 





Intestinal T-cell lymphoma 

• Variable for CD7, CD30 

Enteropathy associated T-cell lymphoma 

• Occurring commonly in western countries in association with celiac disease (small intestine involved) 

• Medium to large cells with mixed inflammatory cells 

• Positive for CD3, CD7, CD103, and cytotoxic markers 


Subcutaneous panniculitis-like 

T-cell lymphoma 

Monomorphic epitheliotropic intestinal T-cell lymphoma 

• Monomorphic medium sized lymphoma cells with no inflammatory component, prominent 

epidermotropism and no association with celiac disease (most common in the small intestine) 

• Occurs in Asian and Hispanic population 

• phenotype positive for CD3, CD8, CD56, TIA1, CD20 (aberrant expression in some cases) 


Indolent T-cell lymphoproliferative disorder of gastrointestinal tract 

• Indolent chronic relapsing disease involving multiple gastrointestinal sites and presenting as mucosal 

thickening 

• Positive for CD3, CD8, TIA1, CD2, CD5, 

• Negative for CD56, CD7, granzyme B 

• Low Ki67 

• T-cell lymphoma of cytotoxic T-cells (CD8+, cytotoxic markers TIA-1, granzyme B, perforin are +) 

• Lymphoma infiltrates the subcutaneous fat and spares dermis/epidermis, with rimming of fat by tumor 

cells 

• Prognosis is good if not associated with hemophagocytosis 

• Should be excluded from cutaneous T-cell lymphomas as these have a worse prognosis 

Mycosis Fungoides • Epidermotropic primary cutaneous T-cell lymphoma with small to medium sized neoplastic cells having 


• Clinically patch, plaque, tumor and erythrodermic stages with dense dermal infiltrate in the tumor stage 

(epidermotropism may no longer be evident in tumor stage) 

• Variants include folliculotropic, pagetoid and granulomatous slack skin variants 

• Positive for CD2, CD3, CD5, CD4 

• Negative for CD8, CD7 (frequently) 

• Cytotoxic CD8+ phenotype has been recognized in cases of pediatric MF 

• Expression of CD30 is associated with large cell transformation (defined as >25% large blastic cells) 

Sezary syndrome • Defined by a triad of erythroderma, generalized lymphadenopathy, and clonal Sezary cells in lymph 

nodes, blood, and skin. Either absolute Sezary count ≥ 1000/μL or CD4: CD8 ≥ 10 or loss of T-cell 

antigens is required (1 of 3) for diagnosis 

• Positive for CD3, CD4, PD1 

• Negative for CD8, CD7, and CD26 

• Poor prognosis 

Hepatosplenic T-cell lymphoma • Aggressive lymphoma of cytotoxic T-cells of gamma delta type commonly involving liver (sinusoids), 

spleen (red pulp), bone marrow (sinusoidal pattern) and sparing the lymph nodes 

• Affects young immunosuppressed individuals 

• Association with isochromosome 7q 

• Positive for CD3, TIA-1, granzyme M 

• Variable CD56, CD8 

• Negative for granzyme B, CD4, CD5, EBV 

Primary cutaneous CD30 

positive T-cell 


Peripheral T-cell lymphoma, 

NOS 

Lymphomatoid papulosis 

• Chronic resolving-relapsing cutaneous disorder with histology mimicking cutaneous T-cell lymphoma and 

a benign clinical course 

• Multiple subtypes with type A being the most common 

Primary cutaneous ALCL 

• CD30+, ALK-negative primary cutaneous lymphoma composed of large cells 

• Exclude MF and systemic ALCL 

• Good prognosis 

• Heterogeneous category comprising of T-cell lymphomas which do not fit any other category 

• Positive for CD3, CD4>CD8, 



Angioimmunoblastic T-cell 

lymphoma 

• Negative or dim for CD5, CD7 


• Aggressive neoplasm of mature T follicular helper cells affecting middle-aged and older adults 

• Immune dysregulation 

• Pale neoplastic cells clustered around HEVs in a polymorphous background (small lymphocytes, plasma 

cells, eosinophils, B immunoblasts) 

• Expanded FDC meshwork around HEVs highlighted by CD21 

• Background B-cells are EBV positive and neoplastic T-cells are negative 

• Positive for CD2, CD3, CD4, CD5 and follicular helper T-cell markers (CD10, CXCL13, ICOS, BCL6, PD1) 


Follicular T-cell lymphoma • Rare neoplasm of T follicular helper cells with a nodular/ follicular growth pattern and absence of 

features characteristic of AITL (no evidence of HEVs, no evidence of FDCs outside of follicles) 

• Follicular lymphoma-like and PTGC-like patterns 

• Immunophenotypically similar to AITL 

• t(5;9) (q33;q22) ITK-SYK seen in a subset of cases and is specific for FTCL 


Anaplastic large cell lymphoma, 

ALK-positive 

Anaplastic large cell lymphoma, 

ALK-negative 

Breast implant-associated large 

cell lymphoma 

• Hallmark cells 

• t(2;5)(NPM-ALK) fusion most common 

• Positive for CD30, ALK, at least some T-cell antigens (CD2, CD4, CD5), cytotoxic markers (TIA-1, 

granzyme B, perforin), CD25, CD43 

• Variable CD45, EMA, CD3, CD8 

• Better prognosis than ALK-negative ALCL 

• Morphologically similar to ALK + ALCL 

• ALK-, CD30+ 

• DUSP22 rearranged can be MUM1+, negative for cytotoxic markers and good prognosis 

• TP63 rearranged are positive for p63 and have a poorer prognosis 

• Associated with breast implants, morphologic features resemble ALCL but is ALK-negative 

• Excellent prognosis 


In a Nutshell: [C] Hodgkin Lymphomas 


Nodular Lymphocyte Predominant 

Hodgkin Lymphoma (NLPHL) 

Classic Hodgkin Lymphoma 

• Nodular sclerosis CHL 

(NSCHL), 

• Mixed cellularity CHL 

(MCCHL), 

• Lymphocyte-rich CHL 

(LRCHL), 

• Lymphocyte-depleted CHL 

(LDCHL) 

• Nodular or vaguely nodular mixed cell proliferation 

• Localized peripheral LNs, B symptoms rare 

• LP cells (Popcorn cells): Lobed nuclei, with smaller basophilic nucleoli with a rim of pale cytoplasm 

• Neoplastic cells positive for CD20, CD45, CD79a, PAX5, OCT2, and BOB1; CD15 and CD30 negative. EBV 

infection in rare cases 

• CD21+FDC meshwork with a predominance of CD20+ B-lymphocytes 

• Six immuno-architectural patterns seen 

• Clonally rearranged IGH genes and frequent BCL6 rearrangement 

• Differential diagnosis: TCRBCL and CHL 

• Good prognosis for Stage I and II 

• Disease not treated after the resection of the affected lymph node in some countries 

• Advanced NLPHL responds better to the R-CHOP used for aggressive B-cell lymphomas 

• MCCHL: Classic HRS cells in a diffuse mixed inflammatory background 

• NSCHL: Lacunar cells (retracted cytoplasmic membrane) with broad fibroblast poor collagen bands 

surround at least one nodule 

• LRCHL: Nodular or diffuse cellular background of small lymphocytes, with an absence of granulocytes 

and scattered HRS cells 

• LDCHL: Predominance of HRS cells and the scarcity of background lymphocytes. Types: Diffuse fibrosis 

subtype and anaplastic subtype 

• Peripheral lymphadenopathy with B symptoms 

• Classic Reed Sternberg cells: large cells with bilobed nuclei, prominent eosinophilic viral inclusion-like 

nucleolus and abundant basophilic cytoplasm 

• IHC crippled B-cell program: Strong membranous and Golgi zone positivity for CD30 (nearly all cases), 

CD15 positive (most cases), PAX5 positive (weaker than that of reactive B-cells), weak and variable CD20 

positivity 

• Type II EBV latency: LMP1 and EBNA1 without EBNA2. Prevalence: MCCHL and LDCHL > NSCHL 

• PDL1+ T-cell rosettes 

• NF-KB is constitutively activated, JAK/STAT signaling pathway 

• Treatment: ABVD, BeACOPP, novel agents (CD30 Mab: Brentuximab), immune checkpoint inhibitors 

(Nevolimumab) 


AML with Recurrent Genetic Abnormalities (translocations) 

In a Nutshell: [D] Acute Myeloid Leukemia 


IN A NUTSHELL: ACUTE MYELOID LEUKEMIA 

AML with t(8;21) • M2, Younger patients; may present as myeloid sarcoma 

• 20% blasts is NOT required for diagnosis 

• Large blasts with abundant cytoplasm, often with granules, hofs, and long tapered Auer rods 

• Bone marrow often shows granulocytic dysplasia and occasionally concurrent systemic mastocytosis 

• CD34+ (bright), HLA-DR+, MPO+, CD13+, CD33 weak, CD15+/-, CD65+/-, CD19+/-, PAX5+/-, CD79a+/- 

• t(8;21) results in RUNX1-RUNX1T1 fusion, often with additional chromosomal abnormalities and mutations in 

KRAS, NRAS, ASXL1, or ASLX2 

• Favorable prognosis overall, worse if CD56 is expressed or KIT mutation is present 

AML with inv(16) or 

t(16;16) 

• M4, Younger adults; may present as myeloid sarcoma 


• BM: increased eosinophils with a spectrum of maturation and abnormal eosinophilic and/or basophilic granules 

• Multiple populations, including immature (CD34+, CD117+), granulocytic (CD13+, CD33+, CC15+, CD65+, MPO+), 

and monocytic (CD14+, CD4+, CD11c+, CD64+, lysozyme+); aberrant expression of CD2 is common 

• Inv(16) or t(16;16) results in CBFB-MYH11 fusion and may be subtle by conventional cytogenetics 

• Secondary chromosomal abnormalities are common (+22, -7q, +21) as are mutations KIT, NRAS, KRAS, and FLT3 

• Favorable prognosis overall, worse if KIT or FLT3 mutation is present 

AML with t(15;17) • M3, Middle-aged patients; associated with coagulopathy and DIC 


• Two morphologic variants: typical (hypergranular promyelocytes and faggot cells) and microgranular 

(hypogranular promyelocytes with “apple-core” or “butterfly”-shaped bilobed nuclei) 

• MPO+, HLA-DR-, CD34-, CD13+, CD33+, CD15 +/-, Microgranular variant: CD34+/- CD2+/- 

• t15;17) results in PML-RARA fusion. Alternate translocations include t(11;17) (resistant to ATRA) and t(5;17) 

• Excellent prognosis when treated with ATRA, which induces differentiation 

AML with t(9;11) • M5, Usually seen in children; may present with DIC, myeloid sarcoma, and/or tissue infiltration 

• Monocytic morphology 

• CD33+, CD65+, CD4+, HLA-DR+, CD34+/-, CD117+/-, CD14+/-, CD4+/-, CD11c+/-, CD64+/- 

• t(9;11) results in KMT2A-MLLT3 fusion; secondary abnormalities are common 

• Intermediate prognosis, worse if MECOM is overexpressed 

AML with t(6;9) • Children and adults; may present with pancytopenia 

• Peripheral blood and bone marrow basophilia (2%) and multilineage dysplasia are common 

• MPO+, CD9+, CD13+, CD33+, CD123+, HLA-DR+, CD117 +, CD34+, TdT +/- 

• t(6;9) results in DEK-NUP214 fusion and is usually the only karyotypic abnormality. FLT3-ITD mutation is common 

• Poor prognosis, especially if high WBC count 

AML with t(1;22) • Infants and young children without trisomy 21; female predominance; presents with marked organomegaly 

• Megakaryoblasts (large, abundant basophilic cytoplasm with cytoplasmic blebbing) and dense marrow fibrosis 

• MPO-, CD41+/-, CD61+/-, CD42b +/-, CD36+, CD13+/-, CD33+/-, CD34-, HLA-DR- 

• t(1;22) results in RBM15-MKL1 fusion and is usually the only karyotypic abnormality 

• Responds well to chemo, but has a worse prognosis than acute megakaryocytic leukemia without t(1;22) 

AML with inv(3) or • Adults; sometimes presents with thrombocytosis and hepatosplenomegaly 

t(3;3) 

• Giant hypogranular platelets, prominent multilineage dysplasia and variable fibrosis in the marrow 

• CD34+, CD13+, CD33+, CD117+, HLA-DR+, CD7 +/-, CD41+/-, CD61+/- 

• Inv(3) or t(3;3) leads to dysregulated MECOM and GATA2. Often other karyotypic abnormalities (-7, -5q) and 

mutations 

• Poor prognosis, especially if complex karyotype with a deletion in chromosome 7 

AML with BCR-ABL1 • Provisional entity; mainly adults; no evidence (before or after treatment) of CML 

• Lacks morphologic characteristics of CML (peripheral basophilia, dwarf megakaryocytes, increased M:E ratio, etc) 

• CD13+, CD33+, CD34+, CD19+/-, CD7+/-, TdT+/- (must exclude MPAL) 

• t(9;22) resulting in BCR-ABL1 fusion, usually with p210 transcript 

• Aggressive with poor prognosis 


AML with Recurrent Genetic Abnormalities 

(translocations) 

AML, NOS 



NPM1 

AML with biallelic 

mutation of CEBPA 


RUNX1 

AML with minimal 


(FAB M0) 

AML without 

maturation (FAB 

M1) 

AML with 

maturation 

(FAB M2) 

Acute 

myelomonocytic 

leukemia (FAB M4) 

Acute monoblastic 

and monocytic 

leukemia 

(FAB M5) 

Pure erythroid 


Acute 




• Adults; female predominance; may present with extramedullary tissue infiltration 

• Myelomonocytic or monocytic features and “cup-shaped” blast nuclei; often shows multilineage dysplasia 

• Immature myeloid (CD33+ (bright), CD13+/-, CD117+, CD123+) or monocytic (CD64+, CD14+) immunophenotype 

• CD34 and HLA-DR negative 

• NPM1 mutations usually involve exon 12; cytogenetic abnormalities are sometimes present 

• Favorable prognosis, especially if normal karyotype and no FLT3-ITD. 

• Children and young adults; must consider germline predisposition 

• No specific morphology or immunophenotype 

• Multilineage dysplasia is common 

• Sometimes additional cytogenetic abnormalities or mutations in FLT3-ITD and/or GATA2 are seen 

• Favorable prognosis 

• Provisional entity, excludes cases than can be placed in other categories, including AMLs with mutated NPM1 or 

CEBPA 

• Older adults; must consider germline predisposition 

• Often shows minimal differentiation, otherwise no specific features 

• Usually CD13+, CD34+, HLA-DR+, CD33+/-, monocytic markers +/-, MPO+/- 

• Usually monoallelic RUNX1 mutation, sometimes with an abnormal karyotype or additional mutations 

• Infants and older adults 

• No morphologic or cytochemical evidence of myeloid differentiation; does not meet criteria for another AML 

category 

•

AML-MRC 

t-AML 

BPDCN 



Acute basophilic 

leukemia 

Acute panmyelosis 

with myelofibrosis 

• Very rare; presents with marrow failure 

• Blasts with coarse basophilic granules and occasionally cytoplasmic vacuoles 

• Usually CD13+, CD33+, CD123+, CD203c+, CD11b+, CD9+, CD34+/-, HLA-DR+/-, CD117- 

• t(X;6) or t(3;6) is often seen 

• Rare, mostly adults; presents with marrow failure and bone pain 

• ≥20% blasts with marrow fibrosis; does not meet criteria for any other AML category and does not have a 

significant number of megakaryoblasts 

• Hypercellular marrow with panmyelosis and diffuse fibrosis; dysplasia is common 

• CD34+, CD117 +/-, CD13+/-, CD33+/-, MPO- 

• Very poor prognosis 

• Criteria (must meet all 3) 

o 20% myeloid blasts 

o Any of the following: 

• History of MDS or MDS/MPN 

• Presence of MDS-defining cytogenetic abnormality 

• Multilineage dysplasia (50% in 2 lineages) 

o Absence of prior cytotoxic or radiotherapy and absence of an abnormality diagnostic of AML with a 

recurrent genetic abnormality 

• An exception to these criteria is cases with NMP1 or biallelic CEBPA and an 

MDS-defining cytogenetic abnormality – in this case, AML-MRC takes diagnostic 

precedence. 

• Mainly elderly; often presents with pancytopenia 

• Variable morphology and immunophenotype 


• Occurs after therapy with cytotoxic agents 

• Two subsets 

o Alkylating agents or radiation 

• Occurs 5-7 years after therapy 

• Complex karyotype; MDS-like genetic alterations 

• Antecedent MDS 

o Topoisomerase inhibitors 

• Occurs 2-3 years after therapy 

• May show balanced translocations, especially of KMT2A or RUNX1 

• Present in overt AML without preceding MDS 

• Often monoblastic or myelomonocytic morphology 

• Poor prognosis, especially if complex karyotype, TP53 mutation, or abnormalities of chromosomes 5 and/or 7 

BPDCN • Aggressive neoplasm derived from precursors of plasmacytoid dendritic cells (PDCs) with a high frequency of 

cutaneous and bone marrow involvement as well as leukemic dissemination 

• Most commonly presents as skin manifestations including isolated purplish nodules, bruise-like papules or 

disseminated purplish nodules, papules, or macules 

• Few cases have been associated with other myeloid neoplasms (CMML>>MDS or AML) 

• Diffuse, monomorphic infiltrate of blastic cells on skin biopsy 

• Positive for CD123, CD4, and CD56 (mnemonic 123-4-56) CD43, CD45RA, other + markers are CD303, TCL1A, 

CD2AP, SP1B, type I interferon dependent molecule MX1, and TCF4 (recently discovered) 

• Negative for CD3, CD13, CD16, CD19, CD20, LAT, lysozyme and MPO 

• Differential includes mature plasmacytoid dendritic cell proliferation (MPDCP), in which PDCs are 

morphologically mature (also associated with myeloid neoplasms) but are CD56 negative 

• Absence of lineage associated antigens with positivity for CD4, CD45RA, CD56, and CD123 is considered 

diagnostic 

• TET2 commonly mutated, T and B clonality studies generally negative 

• Aggressive disease with short survival, recently FDA approved drug tagraxofusperzs binds IL3 receptor (CD123) 

on PDCs to enter and then induce cytotoxicity 

Reference: Swerdlow, S. H., Campo, E., Harris, N. L., Jaffe, E. S., Pileri, S. A., Stein, H., & al, et. (2016). WHO classification of tumors of 

hematopoietic and lymphoid tissues (4th ed.). International Agency for Research on Cancer. 




Myeloid sarcoma • Tumor mass consisting of myeloid blasts, with or without maturation, occurring at an anatomical 

site other than the bone marrow, with effacement of the tissue architecture 

• Commonly involved sites are skin, lymph nodes, gastrointestinal tract, bone, soft tissue, 

testes 

• It may precede or coincide with AML or constitute an acute blastic transformation of MDS, 

MDS/MPN, or MPN 

• Most commonly consists of myeloblasts with or without features of promyelocytic or neutrophilic 

maturation, can also show myelomonocytic or pure monoblastic morphology 

Myeloid 


associated with 

Down Syndrome 

Transient 

abnormal 

myelopoiesis 


Down Syndrome 

Myeloid leukemia 


Down syndrome 

• Unique disorder of newborns with Down syndrome that presents with clinical and 

morphological findings indistinguishable from those of AML 

• The blasts have morphological and immunological features of megakaryocytic lineage 

• Usually diagnosed by the first week of life 

• Thrombocytopenia is the most common presentation 

• In most cases, there is spontaneous remission within the first few months of life; a few 

children experience life-threatening complications 

• Genetics: GATA1 mutation (not a driver mutation, just accelerates megakaryopoiesis) 

• Other mutations acquired in cases that progress to AML 

• Includes both MDS and AML. Most common are AML M7 

• Pre-leukemic phase: MDS/refractory cytopenia 

• AML phase: Blasts and erythroid precursors are usually present in the peripheral blood 

• Genetics: Somatic mutations of the gene encoding the transcription factor GATA 1 

• Young children with Down syndrome and myeloid leukemia with GATA1 mutation have 

favorable prognosis as compared with that of AML in children without Down syndrome 

• Myeloid leukemia in older children with Down syndrome with GATA1 mutation and 

monosomy 7 has a poorer prognosis, comparable to that of AML in patients without Down 

syndrome 


In a Nutshell: [E] Acute Leukemias of Ambiguous Lineage 

Jeremiah Karrs 

Gupta 

Akanksha 

Acute leukemia of 

ambiguous lineage 

Acute undifferentiated 

leukemia (AUL) 

Mixed-phenotype acute 

leukemia (MPAL) with 

t(9;22)(q34.1;q11.2); BCR- 

ABL1 


leukemia (MPAL) with 

t(v;11q23.3); KMT2Arearranged 


leukemia, B/myeloid, not 

otherwise specified 


leukemia, T/myeloid, not 



leukemia, not otherwise 

specified, rare type 

Acute leukemia of 

ambiguous lineage, not 


IN A NUTSHELL: Acute leukemias of ambiguous lineage 

• No definitive evidence of differentiation into a single lineage 

• Includes acute undifferentiated leukemia (AUL) and mixed phenotype acute leukemia (MPAL) 

• AUL has no definitive differentiation toward lymphoid or myeloid 

• MPAL has 1 blast population expressing lymphoid and myeloid markers or 2 blast populations with one 

expressing lymphoid markers and the other expressing myeloid markers 

• Myeloid lineage by MPO (by flow cytometry, IHC or cytochemistry) or monoblastic differentiation (≥2 of NSE, 

CD11c, CD14, CD64, lysozyme) 

• T-cell lineage by cCD3 (by flow cytometry with antibodies to CD3 epsilon chain) or surface CD3 

• B-cell lineage by (multiple antigens required), strong CD19 with ≥1 of the following strongly expressed, 

CD79A, cCD22, CD10 or weak CD19 with ≥2 of the following strongly expressed, CD79a, cCD22, CD10 

• Use extensive workup to exclude unusual lineages 

• Blasts lack myeloid specific Auer rods or cytoplasmic granules 

• Positive for HLA-DR, CD34, and/or CD38 and possibly TDT 

• Negative for cCD3, MPO, B-cell and monocytic markers (NSE, CD14, CD64, lysozyme, CD11c), can have weak 

CD7 expression 

• Fulfills criteria for MPAL with t(9;22) and/or BCR-ABL1 rearrangement 

• Blasts can have a dimorphic appearance with some resembling lymphoblasts and others myeloblasts 

• Most cases meet criteria for B and myeloid blasts although some cases have T and myeloid blasts 

• The p190 fusion transcript is more common than p210 

• Poor prognosis, worse than other MPALs 

• Fulfills criteria for MPAL and has translocation involving KMT2A (previously called MLL) 

• More common in children, particularly infants 

• Possible to recognize distinct monoblastic and lymphoblastic populations by morphology 

• B-ALL with KMT2A rearranged tends to have pro-B immunophenotype (CD10-negative), often CD15+ 

• Fulfill criteria for multiple lineages via demonstration of separate lymphoid and myeloid (usually 

monoblastic) blasts 

• All cases have rearranged KMT2A with the most common fusion partner being AFF1 

• Fulfils criteria for B/myeloid leukemia but not the criteria for any genetically defined subgroup 

• Usually no morphologic distinguishing features, can have a dimorphic appearance 

• MPO positive myeloblasts and monoblasts commonly expressing other myeloid associated markers (CD13, 

CD33, CD117) 

• Expression of the mature B markers such as CD20 is rare and usually a separate population of B 

lymphoblasts 

• Fulfils criteria for T/myeloid leukemia but not the criteria for any genetically defined subgroup 

• Usually no morphologic distinguishing features, can have a dimorphic appearance 

• MPO positive myeloblasts and monoblasts commonly expressing other myeloid markers (CD13, CD33, 

CD117) 

• T-cell component expresses T-cell markers (CD7, CD5, CD2) in addition to cCD3 

• Expression of surface CD3 can occur with a separate population of T lymphoblasts 

• Shows evidence of both T-cell and B-cell lineage commitment, too few cases for further characterization 

• Express a combination of markers that do not classify them as either acute undifferentiated leukemia or 

mixed phenotype acute leukemia 

• Includes cases expressing T-cell associated markers such as CD5 and CD7, but lacking more specific markers 

such as cCD3, along with myeloid associated antigens CD33 and CD13 without MPO 

References • Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al. WHO Classification of Tumours of 

Hematopoietic and Lymphoid Tissues, Revised 4 th Edition. Lyon, France: IARC Press; 2017 


In a Nutshell: [F] Other Myeloid Neoplasms 

Vanya Jaitly 


IN A NUTSHELL: MYELOID NEOPLASMS 

MPN- GENERAL • Elevated blood counts 

• No dysplasia 

• Effective hematopoiesis 

• Organomegaly (splenomegaly due to extramedullary hematopoiesis) 

Entity Peripheral and bone marrow findings Clinical and other key features 

Chronic myelogenous leukemia, 

BCR-ABL1 positive 

CP: Chronic phase 

AP: Accelerated phase 

BP: Blast phase 

Chronic neutrophilic leukemia 

Polycythemia vera 

Polycythemic phase 

Post-polycythemic myelofibrosis/ 

Spent phase 


CP: leukocytosis, myelocyte bulge, basophilia, 

eosinophilia (can be seen), 20% basophils 

10-19% blasts 

Evidence of clonal evolution 

Response to TKI criteria 

BP: ≥20% blasts or extramedullary blast proliferation 

Bone marrow 

CP: ≤5% blasts, ↑ M:E ratio, paratrabecular cuffing by 

immature myeloid cells (>3 cells thick), 

micromegakaryocytes, pseudogaucher cells, increased 

reticulin fibrosis 

AP: 10-19% blasts 

BP: ≥20% blasts 


WBC ≥25000/µL 

Neutrophils + bands ≥80% 

Neutrophil precursors 25% above mean) 

No elevation of serum EPO 

Defined by the presence of BCR-ABL1 fusion gene 

µ-BCR: p230 fusion protein, prominent neutrophilic 

maturation M-BCR: p210 fusion protein, m-BCR: 

p190 fusion protein, associated with Ph-positive ALL, 

In CML associated with increased monocytes 

Clinically chronic, accelerated and blast phase 

20-30% of cases can have lymphoblastic blast crisis 

Tyrosine kinase inhibitors (Imatinib, Dasatinib, 

Sunitinib) is used for treatment. Resistance to 

therapy can occur 

The most important prognostic indicator is the 

response to therapy at hematologic, cytogenetic and 

molecular levels 

CSF3R mutation 

Persistent neutrophilia with normal maturation 

Clinically slowly progressive 

>90% cases have JAK2 mutation most commonly JAK2 

V617F 

2-3% of cases have JAK2 exon 12 mutation 

A subset of patients progress to AML 

Primary myelofibrosis 

Prefibrotic phase 

Fibrotic phase 

Spent phase 

Anemia 

Leukoerythroblastosis 

Bone marrow 

PCV


Vanya Jaitly 


Essential thrombocythemia 

Thrombocythemic ET 

Post-ET myelofibrosis 

Chronic eosinophilic leukemia, 

NOS 

Myeloproliferative neoplasm, 

unclassifiable 

Myeloid/ lymphoid neoplasms 

with eosinophilia and PDGFRA 

rearrangement 

Myeloid/ lymphoid neoplasms 

with eosinophilia and PDGFRB 

rearrangement 

Hypercellular marrow with atypical megakaryocytes 

Fibrotic phase 450 x 10 9 /L 

Post-ET MF 

Anemia 

Leukoerythroblastosis 

Bone marrow 


Vanya Jaitly 


Atypical chronic myeloid 

leukemia, BCR-ABL1 negative 

Juvenile myelomonocytic 

leukemia 

MDS/MPN with ring sideroblasts 

and thrombocytosis 

MDS/MPN unclassifiable 


Leukocytosis with ≥10% neutrophil precursors 

Dysgranulopoiesis 

No basophilia or monocytosis 

Blasts


Vanya Jaitly 


MDS with multilineage dysplasia 

MDS with excess blasts 

Dysplasia in ≥10% cells, in two or more lineages 

Uni or bicytopenia 

In a Nutshell: [G] Other High Yield Topics 

Priya Skaria 


IN A NUTSHELL 

Mastocytosis • Clonal abnormal mast cells in multifocal compact clusters or cohesive aggregates 

• Any age; Heterogeneous: spontaneously regress to aggressive neoplasms with poor survival 

• Giemsa or toluidine blue positive metachromatic mast cell granules, CAE+, MPO- 

• Aberrant CD25 with or without CD2 (+ in 2/3 of cases) in addition to normal CD117, tryptase 

• KIT D816V activating point mutation; if negative, sequence KIT gene 

• Serum tryptase for evaluation and monitoring 

Cutaneous Mastocytosis 

• Common in children with typical lesions before 6 months of age 

• Three forms: Urticaria pigmentosa/maculopapular cutaneous mastocytosis (most common), 

diffuse cutaneous mastocytosis (peau d’orange skin), and mastocytoma of skin 

Systemic Mastocytosis 

• Second decade; no significant sex predilection 

• Five variants; BM almost always involved, skin lesions more often in the indolent form 

• Constitutional symptoms, skin manifestations, mediator-related systemic events, musculoskeletal symptoms, 

organ impairment 

• Anemia, leukocytosis (eosinophilia common), thrombocytopenia, metachromatic blast cells in mast cell 

leukemia 

• Exclude associated lymphoid or myeloid hematologic neoplasm 

Mast cell sarcoma 

• Extremely rare 

• Reported in the larynx, large bowel, meninges, bone, skin 

• Localized destructive growth followed by distant spread and leukemia in several months 

Myeloid/lymphoid neoplasms 

with eosinophilia and gene 

rearrangement 

of PDGFRA, PDGFRB or FGFR1 

or with PCM1-JAK2 

• Rare disease group and provisional entity 

• Aberrant expression of tyrosine kinase 

• Responsive to tyrosine kinase inhibitors 

Myeloid/ lymphoid neoplasms with PDGFRA gene rearrangement 

• Men > women, median: late 40s 

• BCR-ABL1 negative, FIP1L1-PDGFRA gene fusion (cryptic deletion at 4q12); additional cytogenic abnormality 

suggests blastoid transformation 

• Chronic eosinophilic leukemia (normal and abnormal morphology; CD23+, CD25+, CD69+) with prominent 

involvement of mast cell lineage (CD25+ and CD2-), women; wide age range, median: late 40s 

• Most common: t(5;12) leading to ETV6-PDGFRB 

• Variable features of MPN, often chronic myelomonocytic leukemia with eosinophilia 

• Splenomegaly, hypercellular BM, leukocytosis (mast cells CD25+ and CD2+), organ dysfunction 

• Fusion gene monitored by RT-PCR or RNA sequencing 

• Severe: cardiac failure 

Myeloid/ lymphoid neoplasms with FGFR1 gene rearrangement 

• Younger patients; median: 32 yrs 

• Heterogenous; MPN (CEL) or AML/BALL/TALL or mixed phenotype acute leukemia; TALL with eosinophilia 

is a clue to the diagnosis; rare basophilia or polycythemia based on gene fusion 

• BM, peripheral blood, lymph node, liver and spleen 

• Poor prognosis due to higher incidence of transformation; stem cell transplantation at chronic phase 

Myeloid/ lymphoid neoplasms with PCM1-JAK2 

• Wide age range (12-75 yrs); median 47 yrs, male predominance 

• Features of CEL, primary myelofibrosis, erythroid hyperplasia with dyserythropoiesis and dysgranulopoiesis, 

atypical CML, BCR-ABL1 negative with eosinophilia 

• Myeloblastic or B or T lymphoblastic transformation 

• Variants: ETV6-JAK2 and BCR-JAK2 translocations more heterogenous, eosinophilia not common 

• Survival based on presenting phase and leukemic transformation 



Priya Skaria 


Myeloid neoplasms with 

germline predisposition 

• Rare; AML or MDS with inherited or de novo germline mutations (some with additional molecular or 

cytogenetic findings) characterized by specific genetic and clinical findings 

• Inherited syndromes (e.g., Fanconi anemia, dyskeratosis congenita) present in childhood 

• Identified by molecular genetic testing including gene sequencing (Skin fibroblasts is the gold standard) 

• Diagnosis critical for clinical management (mostly allogeneic hematopoietic stem cell transplantation) 

and genetic counseling 

Myeloid neoplasms with germline predisposition without a pre-existing disorder or organ dysfunction 

Acute myeloid leukemia with germline CEBPA mutation 

• Children or young adults (median: 24.5 yrs) 

• Biallelic mutations in CEBPA (encodes granulocyte differentiation factor); evaluate for germline inheritance 

• Acquired GATA2 mutations common 

• AML with or without a mutation, Auer rods+, blasts CD7+, normal karyotype 

• Overall favorable prognosis 

Myeloid neoplasms with germline DDX41 mutation 

• Encodes DEAD box RNA helicase DDX41 

• Minority of myeloid neoplasms; long latency, mean: 62 yrs 

• Leukopenia with or without other cytopenias or macrocytosis, hypocellular BM with erythroid dysplasia 

• Normal karyotype 

• Progress to high grade neoplasms: MDS with multilineage dysplasia, MDS with excess blasts, MDS with 

isolated del(5q), AML (mostly erythroleukemia); CML and lymphomas also reported 

Myeloid neoplasms with germline predisposition and pre-existing platelet disorders 

Myeloid neoplasms with germline RUNX1 mutation 

• Autosomal dominant familial platelet disorder with predisposition to AML at a young age (median: 33 yrs) 

• Germline monoallelic mutations in RUNX1 (encodes one subunit of core binding transcription factor) 

• Normal to mild thrombocytopenia with impaired aggregation with collagen and epinephrine and dense 

granule storage pool deficiency; mild to moderate bleeding tendency from childhood 

• MDS, AML with or without maturation, Auer rods 

• Point mutations, frameshift mutations, deletions, duplications, rearrangements 

Myeloid neoplasms with germline ANKRD26 mutation (Thrombocytopenia 2) 

• Increased gene transcription and signaling through the MPL pathway and impaired proplatelet formation 

• Moderate thrombocytopenia, glycoprotein 1a, and alpha granule deficiency, elevated thrombopoietin 

• Early stable dysmegakaryopoiesis and thrombocytopenia that may not progress to AML or MDS for decades 

• Myeloid neoplasms 30 times higher than the general population 

Myeloid neoplasms with germline ETV6 mutation (Thrombocytopenia 5) 

• Autosomal dominant familial thrombocytopenia and hematological neoplasms 

• Disrupted nuclear localization of ETV6 transcription factor and reduced expression of platelet associated 

genes 

• Mild to moderate bleeding tendency, occasionally in infancy 

• Small hyposegmented megakaryocytes, mild dyserythropoiesis 

• MDS, AML, CMML, BALL, plasma cell myeloma, colorectal adenocarcinoma 

• Early stable dysmegakaryopoiesis and thrombocytopenia that may not progress to AML or MDS for decades 

Myeloid neoplasms with germline predisposition associated with organ dysfunction 

Myeloid neoplasms with germline GATA2 mutation 

• Monoallelic germline GATA2 mutations leading to haploinsufficiency; highly prevalent with monosomy 7 

• Constitute most of the advanced MDS and subset of all MDS cases in children and adolescents 

• Anemia, neutropenia, or thrombocytopenia; immunodeficiency with reduced monocytes, B-cells, NK cells, 

lymphoedema; severe infections in null mutations 

• Majority at median 29 yrs of age develop MDS with high risk evolution to AML or CMML, a subset with AML 

• BM hypocellularity and multilineage dysplasia (prominent dysmegakaryopoiesis), plasma cells CD56+, 

increased T-cell large granular cell lymphocytes 

• Generally poor prognosis; improved with stem cell transplantation in patients with MDS 

Myeloid neoplasms with germline predisposition associated with inherited bone failure syndromes and telomere 

biology disorders 

• Highly variable phenotypes, may go undiagnosed until childhood 



Priya Skaria 


Post-transplant 


• MDS and AML are the most common hematologic neoplasms 

• Lymphoid or plasmacytic proliferations due to immunosuppression following solid organ or stem cell 

transplant 

• Higher incidence in children and >50 yrs (most common with heart-lung, lung, intestine transplant recipients) 

• EBV seronegativity at the time of transplantation is the most important risk factor 

• Early onset PTLD (


Priya Skaria 


Lymphomas associated with 

HIV infection 

Other iatrogenic 

immunodeficiency associated 


Histiocytic and dendritic cell 

neoplasms 

• Most commonly seen in Ataxia-telangiectasia, Wiskott-Aldrich Syndrome, Common invariable 

immunodeficiency, Severe combined immunodeficiency, X-linked lymphoproliferative disease, Nijmegen 

breakage syndrome, Hyper-IgM syndrome, and Autoimmune lymphoproliferative syndrome 

• Extranodal sites>Nodal: Mostly DLBCL, others: CHL, Burkitt lymphoma, PTCL, LyG, Fatal IM, etc 

• EBV association (CD30+, caution: EBV infection of B-cells leads to downregulation of CD19, CD20, CD79a ) 

• Lymphoid proliferations and lymphomas (mostly aggressive B-cell lymphomas) in HIV patients (CD4 counts) 

• cART: 50% decrease in all NHL subtypes and increase in CHL 

• Extranodal sites predominantly: Multistep lymphomagenesis (B-cell stimulation→LAD→lymphoma), EBV, 

HHV8 

• PEL, plasmablastic lymphoma, and HHV8-positive DLBCL, NOS, occur more specifically in HIV-positive patients 

• MYC gene rearrangements in DLBCL increased mortality 

• Lymphoid proliferations or lymphomas associated with immunosuppressive therapy (mostly methotrexate) 

for autoimmune diseases (rheumatoid arthritis most common) or conditions other than post-transplant 

setting 

• Factors: Underlying disorder, immunosuppressive agent, chronic inflammation, host genetics 

• Extranodal sites: similar presentation as in immunocompetent hosts 

• DLBCL (activated B-cell type) > CHL (mixed cellularity) > other lymphomas and lymphoid proliferations 

including EBV+ mucocutaneous ulcer (CD20+, CD30+, CD15-, variable EBV positivity with type II latency more 

than type III) 

• Discontinue therapy, chemotherapy, allogenic SCT 

• Rarest tumors presenting in the lymph nodes or soft tissue 

• Histiocytic neoplasms derived from mononuclear phagocytes or histiocytes 

• Dendritic cell tumors are derived from the myeloid and stromal-derived dendritic cells 

• Associated or preceded by malignant lymphoma; transdifferentiation with identical IG and TR 


• Phagocytic activity is not a prominent feature of histiocytic malignancy 

• Localized disease has relatively favorable prognosis compared to widespread disease 

Histiocytic sarcoma 

• Wide patient age range, from infancy to old age (predominantly males) 

• Associated with malignant mediastinal teratoma or malignant lymphoma 

• Fever, weight loss, intestinal obstruction, skin rash/ lesions, pancytopenia, lymphadenopathy, rare systemic 

• Diffuse non-cohesive proliferation of monomorphic or pleomorphic large cells with abundant vacuolated 

cytoplasm in a reactive background 

• Positive: CD163, CD68, lysozyme, CD45, 45RO, HLA-DR, CD4 

• Isochromosome 12p, BRAF V600E 

• Aggressive neoplasm with poor response to therapy 


• Childhood, white males > females, smokers (LCH of the lung) 

• Transdifferentiation from TALL 

• Solitary or multifocal/ multiple sites: bone and adjacent soft tissue (skull, mandible; lytic lesions eroding 

cortex), skin, liver, spleen, BM 

• Mild nuclear atypia, mitosis, osteoclasts type cells, eosinophils, neutrophils, lymphocytes, plasma cells 

• Sinus pattern and paracortex infiltration in lymph nodes, nodular splenic red pulp, sclerosing cholangitis, 

• Positive: CD1a, langerin, S100, CD68, HLA-DR, PDL1, low CD45 and lysozyme, variable Ki67 

• BRAF V600E mutation, MAP2K1, some with clonal IGH, IGK or TR 

Langerhans cell sarcoma 

• Rare, aggressive high-grade neoplasm in adults 

• Extranodal, multifocal, stage III-IV; skin and underlying soft tissue, lymph nodes, lung, liver, spleen, bone 

• Malignant pleomorphic LC cells with >50 mitoses per 10 HPF 

• Occasional BRAF V600E mutation 

Indeterminate dendritic cell tumor 

• Extraordinarily rare, one or multiple generalized papules, nodules, or plaques on the skin with dermal 

involvement 

• Diffuse LCH-like cells with irregular nuclear grooves and typically abundant eosinophilic cytoplasm, 

eosinophilic infiltrate usually not present, lack Birbeck granules 

• S100+, CD1a+, langerin -, variable CD45, CD68, lysozyme and CD4 

• Rare BRAF V600E mutation, spontaneous regression or rapid progression 



Priya Skaria 


Interdigitating dendritic cell sarcoma 

• Extremely rare neoplasm in adults and children, males > females 

• Solitary lymph node lesion or extranodal: skin, soft tissue, hepatosplenomegaly 

• Fascicles of spindle cells in the paracortex, abundant eosinophilic cytoplasm, complex interdigitating 

processes, Birbeck granules not seen, 7 cm) or abdominal pain, rare paraneoplastic pemphigus 

• Storiform whorls of bland (1-10 mitosis) to pleomorphic (>30 mitoses) cells with cytoplasmic processes and 

no Birbeck granules, lymphocyte aggregates around blood vessels, epithelioid tumor cells 

• Positive: CD21, CD23, CD35, Clusterin, CXCL13, podoplanin, FDCSP, Serglycin, PDL1 

• EBV negative 

• Complex karyotype, negative regulation of NF KappaB pathway, BRAF V600E mutation 

• Worse prognosis: >6.0 cm tumor size, coagulative necrosis, ≥5 mitosis, marked cytologic atypia, refractory 

paraneoplastic pemphigus. 

Inflammatory pseudotumor-like follicular/ fibroblastic dendritic cell sarcoma 

• Young to middle-aged females, liver or spleen or GIT (polypoid lesion) 

• Prominent lymphoplasmacytic infiltrate, variable nuclear atypia, hemorrhage, and necrosis, fibrinoid deposits 

blood vessels, massive eosinophils or epithelioid granulomas 

• Consistently EBV+; CD21, CD35, SMA +/- 

• Indolent or intraabdominal recurrences 

Fibroblastic reticular cell tumor 

• Very rare; involves lymph node, spleen, or soft tissue 

• Blunt spindle cells arranged in poorly formed whorls, with moderate cytological atypia 

• Variable SMA, Desmin CK (dendritic pattern), CD68 

• Variable clinical outcome, some fatal 

Disseminated juvenile xanthogranuloma 

• Association: NF1; high risk of JMML 

• Deep, visceral, and disseminated forms occur by the age of 10 years; half within first year of life 

• Skin and soft tissue (commonly, head and neck), upper aerodigestive tract, CNS, eye, liver, lung, LN, BM 

• Proliferation of foamy histiocytes with Touton-type giant cells, Touton cells less common at non-dermal sites, 

• Positive: Vimentin, CD14, CD68, CD163, Factor XIIIa, fascin, subset S100 

• Negative: CD1a and langerin, BRAF 

• All clinical forms are benign, LCH therapy; severe: MAS with cytopenias and liver damage, multiple CNS 

lesions 

Erdheim-Chester disease 

• Clonal systemic proliferation of non-Langerhans cell histiocytes, subset with concurrent LCH 

• Rare, male preponderance 

• Bones, CVS, pituitary gland, eye, skin 

• Coated aorta, diffuse pleural thickening, bilateral symmetrical cortical osteosclerosis of long bones 

• Foamy xanthomatous histiocytes, Tuton-type giant cells, fibrosis, reactive small lymphocytes, plasma cells, 

neutrophils 

• Positive: CD14, CD68, CD163, fascin, Factor XIIIa, BRAF 

• Negative: S100 (rare positive), CD1a and langerin 

• Mutations: BRAF V600E (targeted therapy), NRAS, PI3KCA pathway gene 

• Severe – cerebellar degeneration, renovascular hypertension, multisystem involvement, increased CRP

11-28 KDP Ebook

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