Abstract

Epithelioid hemangioma (EH) is a benign vascular tumor of the skin and subcutaneous tissue with a wide anatomic distribution but most commonly affecting the head and neck and distal extremities. Only rarely has EH been reported to affect the penis, where histologic evaluation often shows features that can cause concern for malignant vascular tumors such as epithelioid hemangioendothelioma (EHE) or epithelioid angiosarcoma (EAS). Immunohistochemistry may aid in definitive diagnosis when such histopathologic overlap occurs. We present a case of EH involving subcutaneous tissue of the base of the penis in a 67-year-old man. Microscopic examination revealed a circumscribed and vaguely lobulated mass with numerous lymphocytes and occasional neutrophils at the periphery. The tumor was comprised of spindled to epithelioid cells, the latter with vesicular chromatin and variably prominent nucleoli, that formed sheets in areas, displaying morphologic overlap with both EAS and epithelioid angiomatous nodule. The tumor showed evidence of vasoformation but lacked brisk mitotic activity or necrosis. Immunohistochemistry (IHC) revealed diffuse positivity for ERG, CD31 and FOSB, confirming endothelial differentiation. Tumor cells lacked expression of CAMTA1, further arguing against EHE. HHV8 was negative, excluding Kaposi sarcoma. Together with the well-circumscribed appearance and lack of significant mitotic activity, a diagnosis of EH was rendered. EH of the penis, although rare, is often of the cellular subtype, representing a potential diagnostic pitfall, and must be distinguished from malignant vascular tumors.

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