Multifocal Pseudomyogenic Hemangioendothelioma Involving the Scalp and Nose, Misdiagnosed as A Sarcoma: A Rare Case Report.

This case report aims to present clinicopathological features of an extremely rare case of multifocal pseudomyogenic hemangioendothelioma (PMHE) in the scalp. A 21-year-old male developed multiple, focally ulcerated, nodules over the root of his nose and scalp. One of the skin lesions was sampled at another dermatology clinic, where this was diagnosed as a sarcoma. A review of biopsy sections showed well-circumscribed dermal lesions, comprising plump spindle and epithelioid cells, mimicking rhabdomyoblasts. Immunohistochemically, tumor cells were positive for AE1/AE3, CD31, FLI-1 and ERG. INI-1 was retained. A diagnosis of PMHE was offered. Subsequently, the patient underwent wide excision and has been asymptomatic for 8 months, post-surgery. PMHE is rarely reported in the head and neck region, where it can constitute a diagnostic pitfall. Awareness of this tumor and appropriate immunohistochemical stains are necessary for its timely diagnosis, in order to avoid radical treatments. A review of similar, previously documented cases is presented.