Angiosarcoma with pseudoepidermotropism in a patient with breast cancer: a mimic of epidermotropic metastatic adenocarcinoma.

We report a case of cutaneous postradiation angiosarcoma of the breast exhibiting pseudoepidermotropism that resembled metastatic adenocarcinoma on hematoxylin and eosin. The patient is a 74-year-old woman with history of breast carcinoma treated with mastectomy, chemotherapy, and radiotherapy who complained of an erythematous "rash" along the central portion of the mastectomy scar. Radiography showed widespread osseous metastasis. Biopsy revealed an infiltrative tumor with single file growth and tumor cells obscuring the dermal--epidermal junction in multiple foci, imparting an appearance of epidermotropism. The tumor cells were positive for CD31, CD34, and D2-40 and negative for Cam 5.2. This novel case of pseudoepidermotropic angiosarcoma highlights a potential pitfall in the histomorphologic assessment of poorly differentiated angiosarcoma.