Post-radiation Epithelioid Angiosarcoma of Breast: Case History: The patient was a 60 y/o female who underwent lumpectomy for invasive ductal carcinoma, followed by 6 courses of chemotherapy and radiation therapy (total dose of 6500 cGy). She presented with a breast mass 12 years later. A core-needle biopsy showed a high-grade spindle cell neoplasm and mastectomy was performed. The specimen showed a 6 cm hemorrhagic, soft, spongy mass with a few firm areas. Microscopic examination revealed a high-grade malignancy with epithelioid and spindle cells in solid sheets as well as slit-like spaces containing erythrocytes and lined by highly atypical cells. This image shows a solid focus with highly atypical epithelioid cells, some of which contain intracytoplasmic lumina. Strong immunoreactivity for CD31 and CD34 and negativity for AE1/AE3, combined with the clinical history, permitted the diagnosis of radiation-induced angiosarcoma of breast.