BREAST CYTOPATHOLOGY

Special Types of Breast Carcinomas 133
• There are three forms of breast angiosarcomas: (1) primary
angiosarcomas, (2) secondary angiosarcomas related to
lymphedema due to mastectomy, and (3) secondary angiosarcomas
related to radiation therapy following surgery.
• Angiosarcomas can be histologically graded into a
three-tiered system: grade I (well-differentiated), grade II
(intermediate differentiation), and grade III (poorly
differentiated).
• Immunostains for factor VIII, CD34, and CD31 are helpful
in characterizing the endothelial differentiation.
Cytomorphologic Characteristics
• Sparse cellularity, often blood-stained smears
• Single round to spindled hyperchromatic cells with prominent
nucleoli
• Collagenized stroma
• Hemosiderin-laden macrophages, fibrin, necrosis
• May contain branching vessels in “tangles”
Pitfalls and Differential Diagnosis
• “False negativity” can be caused by scant cellularity and
abundant blood.
• Atypical hemangioma of the breast may mimic an
angiosarcoma.
• Radiotherapy-related changes may have overlapping cytologic
features.
• Resolving hematoma/granulation tissue may also have
similar cellular contents and may also be blood stained,
mimicking the appearance of an angiosarcoma.
Malignant Phyllodes Tumor (Cystosarcoma Phyllodes)
Cystosarcoma phyllodes is an uncommon malignant tumor
with heterogeneous morphology consisting of both epithelial
and stromal elements. The cellularity and character of its
stromal component is the most important feature distinguishing
it from fibroadenoma. Only a small percentage (<10%)
of phyllodes tumors are histologically overtly malignant.