Angiosarcoma of the Pelvis in a 13-Year-Old Girl.

Angiosarcomas are highly aggressive malignancies of vascular origin and are very rarely found in children. We report a case of a 13-year-old girl with a history of abdominal pain and increased abdominal girth. Radiologic imaging showed significant ascites and large pelvic masses involving bilateral adnexa with abdominal spread. Microscopic examination of a biopsy revealed pleomorphic epithelioid and spindle cells with brisk mitotic activity, intracytoplasmic vacuoles, vascular channels, and large areas of hemorrhage and necrosis. Immunohistochemistry analysis showed strong and diffuse positivity for CD31, D2-40, ERG, FLI-1, and focally for CD34, vWF, and EMA. The diagnosis of metastatic angiosarcoma was rendered. The patient was treated aggressively with systemic chemotherapy, immunotherapy, cytoreductive surgery, and hyperthermic intraperitoneal chemotherapy, with a favorable response after 1-year follow-up. Angiosarcoma should be considered when encountering a vascular tumor with pleomorphism, brisk mitotic activity, and necrosis. Immunohistochemistry studies are necessary for proper diagnosis.