Diagnostic cytopathology in type II angiosarcoma of the breast: a case report.

Background: The rare occurrence of angiosarcoma of the breast is reflected in limited descriptions of fine needle aspiration (FNA) cytomorphologic findings in this neoplasm. We present a case of angiosarcoma of the breast and discuss the pitfalls in diagnostic cytopathology that can potentially lead to incorrect diagnoses in such cases.

Case: A 45-year-old woman presented with a 2-year history of a right-sided breast mass. FNA cytology revealed a hypocellular smear composed of cohesive ductal epithelial cells; isolated or loosely arranged, round to spindle-shaped fibroblastlike cells; and projectile growths of round, oval and polygonal cells on loose tangles of connective tissue. The background was hemorrhagic, with scattered foam cells. The overall cytologic diagnosis was inconclusive but suggested phyllodes tumor (of borderline malignancy). Excisional biopsy was performed, followed by simple mastectomy. Histologic features were consistent with angiosarcoma, a diagnosis that was supported by immunohistochemical studies.

Conclusion: On FNA smear, 49.1% of isolated atypical cells were positive for the endothelial marker CD34; however, cytomorphologic appearance of these cells resembled that of CD34-negative active mesenchymal cells. Angiosarcoma rarely occurs in the breast, and a definitive diagnosis is difficult based on cytologic examination of hypocellular smears alone. However, the presence of atypical round, oval and polygonal cells on loose tangles of connective tissue, suggesting sheared vasculature, can be an important diagnostic feature.