Primary Breast Angiosarcoma : Differential
High-grade angiosarcomas of the breast should be distinguished from high-grade ductal carcinoma, metaplastic breast carcinomas, metastatic carcinoma to the breast, and melanoma. Immunohistochemistry is essential in making this distinction. Breast angiosarcomas are positive for vascular markers (CD31, CD34, ERG, FLI-1, and Factor VIII) whereas non-vascular tumors are negative. EMA and cytokeratins are negative except for epithelioid areas. Estrogen and progesterone receptors are negative in most breast angiosarcomas. One study found Ki-67 labeling index useful in separating benign vascular tumors like hemangiomas (low index) from low-grade angiosarcomas (high labeling index). The image shows high-grade (Grade III) primary angiosarcoma of the breast. The tumor has spindle cell morphology with nuclear atypia, clumped chromatin, punctate nucleoli, and increased mitotic activity. Necrosis was also seen.