Primary breast angiosarcoma: pathological and radiological diagnosis.

Primary breast angiosarcoma is a very rare aggressive mesenchymal tumor, which may represent only 0.04% of all breast malignant tumors. We report a case of primary angiosarcoma in the breast of a 22-year-old woman who presented with a mass in her right breast. Ultrasonography revealed a large heterogeneous lobulated mass lesion consistent with a fibroadenoma or phyllodes tumor. After a period of six months, she presented with nipple retraction, so a core needle biopsy was performed. Histopathology revealed a well differentiated angiosarcoma (grade I/III), but in the mastectomy specimen, numerous neoplastic multinucleated giant cells were evident, which resembled those found in other sarcomas, such as malignant fibrous histiocytoma or extra skeletal osteogenic sarcoma, and this caused difficulty making the diagnosis. Using immunohistochemical (IHC) studies, neoplastic cells were positively stained for CD31, CD34, and factor VIII-related antigens, which confirmed that the tumor was a high grade, poorly differentiated angiosarcoma (grade III/III). In conclusion, angiosarcomas may have different grade patterns in the same tumor, and as a result it is necessary to examine the whole tumor for definite grading. Imaging findings in angiosarcomas are non-specific, therefore they may misdiagnosed, frequently by other benign lesions.