Pseudomyogenic hemangioendothelioma presenting as a penile lesion.

Pseudomyogenic hemangioendothelioma (PHE) is a rare, usually multifocal neoplasm typically affecting individuals in the second-to-fourth decade of life, with a male predominance. It often arises in the distal extremities and characteristically involves multiple tissue planes. Presentation of this neoplasm as a primary penile lesion is exceedingly rare, with only five cases previously documented in the literature. We report the clinicopathologic features of five additional PHEs presenting as primary penile tumors and review previously published cases. Tumors affected young to middle-aged adult patients and had a relatively bland clinical appearance, mimicking indolent lesions such as epidermal inclusion cysts. Microscopically, they were ill-defined nodules composed of plump spindle cells and round neoplastic cells with abundant, densely eosinophilic cytoplasm and eccentric nuclei resembling rhabdomyoblasts. Neoplastic cells demonstrated infiltrative growth, including foci of perineural invasion. Immunohistochemistry demonstrated invariable co-expression of keratins, endothelial markers (CD31 and/or ERG), and FOSB. In conclusion, penile PHE is rare but should be considered in the differential diagnosis of penile lesions with spindle cell and/or rhabdomyoblast-like morphology affecting young to middle-aged adult patients.