BREAST CYTOPATHOLOGY

106 4. Primary Malignant Tumors
• The age group is the same as that for the usual invasive
breast carcinomas NOS.
• Patients present with a solid mass.
• This subtype of tumor is associated with vascular invasion
and the presence of lymph node metastasis, that is, lymphotropism,
skin and chest wall recurrences, advanced
stage at presentation, and expression of unfavorable prognostic
markers.
• Axillary lymph node metastasis is usually present in about
75% of the patients.
Cytomorphologic Characteristics
• Tumors have distinctive cytomorphologic features.
• There are three-dimensional tissue fragments (“cell balls”),
acini, and papillary structures of hyperchromatic cells with
crowded nuclei. No fibrovascular cores are present, and
there are few single cells.
• The morulae have tightly cohesive malignant cells
with smooth, rounded outer borders or “community
borders.”
• Enlarged hyperchromatic nuclei, prominent nucleoli, and
high nucleus to cytoplasm ratios.
• Few cases show prominent apocrine morphology.
• Focal mucinous background can be seen.
• Rare cases have psammoma bodies.
• Apical cytoplasm is toward the periphery, while the nuclei
are toward the center in these clusters. The reverse polarity
can be demonstrated in cell block sections using epithelial
membrane antigen immunostain.
• Blood is often abundant and contains hemosiderin-laden
macrophages.
Pitfalls and Differential Diagnosis
• Papilloma, papillomatosis
• Ductal carcinoma in situ, micropapillary type
• Metastatic papillary ovarian serous carcinoma
• Apocrine carcinoma