Pseudomyogenic Hemangioendothelioma (Epithelioid Sarcoma-Like Hemangioendothelioma)

Pseudomyogenic hemangioendothelioma (PMH) is a rare vascular tumor that presents more frequently in young adults and has a male predominance. It is usually located in the superficial or deep soft tissues of the extremities, but concurrent bone involvement can be present. In approximately two-thirds of patients this disease is multifocal, often involving multiple tissue planes. It is a relapsing lesion with low metastatic potential. Given its clinical and morphologic characteristics (multifocality, epithelioid morphology, absence of clearly evident vascular differentiation on hematoxylin-eosin slides), PMH can be easily misinterpreted as other lesions, often with radically different treatment and prognosis. For this reason, we think it is important to recognize this entity, which has some unique features. Here, we will briefly describe the clinical and pathologic features of PMH, detailing its more relevant differential diagnoses.