Pseudomyogenic Hemangioendothelioma.

Pseudomyogenic hemangioendothelioma (PMHE) is a new entity. It is an intermediate soft tissue tumor clinically and/or histopathologically mimicking some other high-grade malignant tumors and some inflammatory diseases. We report a case of PMHE on the left plantar surface of a 28-year-old woman. Histopathological examination of the resected specimen revealed spindle and epithelioid cells with plump and atypical nuclei proliferated in the dermis and subcutaneous fat tissue with marked fibroplasia. Both spindle and epithelioid cells had abundant eosinophilic cytoplasm. Neoplastic cells were diffusely positive for AE1/AE3, CK7, vimentin, CD31, FLI-1, ERG, and INI-1. From those findings, we made the diagnosis of PMHE. We describe the main points of differentiation between PMHE and diseases that have similar clinical and/or histopathological findings, including cellular dermatofibroma, spindle cell squamous cell carcinoma, epithelioid sarcoma, epithelioid hemangioendothelioma, epithelioid angiosarcoma, nodular or proliferative fasciitis, and granulomatous fibrosing granulation tissue due to a ruptured epidermal cyst.