Pseudomyogenic Hemangioendothelioma: Case Report and Review of the Literature

9 Pseudomyogenic hemangioendothelioma (PHE; epithelioid sarcoma-like hemangioendothelioma) is a rare entity, with 129 reported cases. It is a rarely metastasizing, low-grade vascular tumor that can histologically mimic epithelioid sarcoma and often presents as multiple discontinuous nodules in the extremities. PHEs characteristically and consistently show immunoreactivity for cytokeratins and endothelial markers. We present a case in the thigh of a 65-year-old-man with a 3-month history of painful lesions in the dermis and review the published literature. In our case, the lesion exhibited the characteristic histologic findings and immunoprofile of a PHE: a solid proliferation of spindled to epithelioid cells with abundant eosinophilic cytoplasm and frequent rhabdoid cells. Cytologic atypia and mitotic figures were inconspicuous. The tumor cells were immunoreactive for CD31, ERG, AE1/3, and CK7 and negative for D2-40, P53, HMB45, desmin, CD34, SMA, EMA, and S100 protein. A balanced reciprocal translation between chromosomes 7 and 19 was present; this translocation seems unique to PHE. PHE is a unique and commonly misdiagnosed entity; therefore, we review the literature to describe the characteristics of this tumor.