The clinicopathological spectrum of pseudomyogenic hemangioendothelioma: report of an additional series with review of the literature.

We present here our experience with 24 cases of pseudomyogenic hemangioendothelioma (PMHE) to further delineate its clinicopathological spectrum. There were 18 males and 6 females with a median age of 28 years (range 10~64 years). Most patients presented with erythematous nodules or papules, with or without pain. The majority (63%) occurred in the lower extremities, whereas a minority involved the trunk (25%), upper extremities (8%), and head and neck (4%). Six cases (25%) had a primary bone origin. With physical and radiological examinations, 16 cases (67%) manifested as multifocal disease, involving multiple tissue planes or different bones within the anatomic region. Six cases (25%) involved skin, soft tissue, and bone simultaneously. Histologically, all cases showed features consistent with a PMHE characterized by loose fascicles or sheets of plump spindled to epithelioid cells harboring brightly eosinophilic cytoplasm and vesicular nuclei. In addition, five cases (21%) contained a prominent myxoid matrix, and one case displayed perineural and intravascular invasion. The follow-up information available in 18 patients revealed local recurrence in 4 patients (22%) and persistent disease in 8 patients (44%), respectively. One patient developed bilateral pulmonary metastases which showed significant remission after systemic chemotherapy. None of the patients died of the disease. As the clinical appearance of PMHE can be deceptive, a radiological examination is essential in identifying an insidious multifocal disease. Although PMHE has a predilection for the distal extremities of young males, this rare tumor type could also occur in unusual sites and affect middle-aged adults of both genders. The striking myoid appearance in association with myxoid stromal change may represent a potential diagnostic pitfall. Biologically, PMHE has an indolent clinical behavior, albeit metastatic disease may occur in rare instance.