Primary adrenal angiosarcoma: A case report and review of the literature.

Primary adrenal angiosarcoma is an extremely rare malignant tumor with challenging diagnosis. A 66-year-old woman had a 4.3 cm right adrenal mass suspicious for adrenal cortical carcinoma. Pathological examination demonstrated a hemorrhagic adrenal cyst with numerous irregularly shaped anastomosing vascular channels lined by atypical endothelial cells that had frequent atypical mitotic figures (12/10 HPF, Ki67 10%). The tumor cells were positive for CD31, ERG, and FLI-1, but negative for adrenal and other tumor lineage markers by immunohistochemistry. NGS fusion gene testing ruled out epithelioid hemangioendothelioma. Accurate diagnosis and differential inclusion are important for appropriate treatment of this rare tumor.