Guidelines on Diagnosis and Treatment of Malignant Lymphomas

Angioimmunoblastic
T-Cell Lymphoma
Definition and Incidence
Angioimmunoblastic T-Cell Lymphoma, AILT (formerly AILD) is a
peripheral T-cell lymphoma characterised by systemic symptoms,
a polymorphous infiltrate involving lymph nodes, with a prominent
proliferation of high endothelial venules and follicular dendritic
cells. It occurs in the middle aged and elderly, with an equal
incidence in males and females.
ICD-O Code 9705/3
Clinical Presentation
Patients usually present with B symptoms, generalised peripheral
lymphadenopathy, hepatosplenomegaly, and frequent skin rash.
The bone marrow is commonly involved. Para-neoplastic
manifestations are common and include skin rashes, autoimmune
haemolytic anaemia, hypergammaglobulinaemia, eosinophilia,
vasculitis, and haemophagocytosis. The clinical course is
aggressive, with a median survival of less than 3 years.
Pathology and Genetics
The lymph node architecture is partially effaced, and regressed
follicles are often present. The paracortex is diffusely infiltrated by
a polymorphous population of medium-sized lymphocytes, usually
with clear to pale cytoplasm and distinct cell membranes. The
lymphocytes show minimal cytological atypia, and this form of
lymphoma may be difficult to distinguish from atypical T-zone
hyperplasia. The abnormal lymphoid cells are admixed with small,
reactive lymphocytes, eosinophils, plasma cells and histiocytes.
There is marked proliferation of high endothelial venules and
follicular dendritic cell meshworks are often increased. Increased
numbers of B immunoblasts are usually present in the paracortex.
Immunophenotype
The infiltrates are composed of mature T-cells, usually with an
admixture of CD4 and CD8 cells, with CD4 cells usually outnumbering
CD8 cells. Follicular dendritic cells (CD21+) are
prominent. The neoplastic T-cells may aberrantly express CD10.
Genetics
T-cell receptor genes are rearranged in 75% of cases.
Immunoglobulin gene rearrangement is present in 20-30%,
correlating with clonally expanded EBV+ B cells. Gene expression
studies confirm that the neoplastic cells are CD4+ TFH type.
Staging
As for other aggressive lymphomas.
Recommended Investigations
As for other aggressive lymphomas.
Potential Pitfalls
Failure to diagnose lymphoma in the context of a clinical
presentation characterised by a profound immune disturbance.
Treatment
Treatment options include CHOP or CVP-like regimens,
depending on patient age and co-morbidity. There is a high
initial response rate with these approaches, but early relapse or
progression is common and there are few long-term survivors.
Long term disease control may be achieved with weekly
methotrexate and prednisolone. High dose therapy and
autologous SCT have been reported by the EBMT to results
in a 5 year 60% disease free survival.
Response Evaluation and Follow Up
As for other aggressive lymphomas.
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