A case of intravascular myopericytoma on the thigh

Abstract

Myopericytoma is a benign subcutaneous tumor that occurs in the limbs of adults; a rare variant of myopericytoma occurs intravascularly. A 43-year-old man presented with a 3-year history of a 15-mm mass in the subcutis of his right inner thigh. The patient had no history of trauma, although due to his work he had to stand for 8 hours per day. Several tumor lesions were scattered in the subcutaneous tissue. Oval and spindle cells with no atypia were collected around the endothelial cells in a concentric arrangement. By immunostaining, tumor cells were positive for smooth muscle actin and negative for desmin, CD31, CD34, and factor VIII, which suggests the tumor was present in a vessel. Based on these findings, the lesion was diagnosed as intravascular myopericytoma (IVMP). To clarify the etiology of IVMP, we compared our case with 15 previously diagnosed cases of intravascular myopericytoma by age, sex, duration, site, and morphology. Thus, we hypothesized that venous reflux could be a cause of intravascular myopericytoma in the legs due to prolonged standing at work.