Intravascular myopericytoma: an interesting case of a long-standing large, painful subcutaneous tumor.

Myopericytoma is a benign neoplasm consisting of cells that appear to have a distinct differentiation towards presumed perivascular myoid cells. Amongst myopericytoma, an intravascular variant appears to have been reported only rarely. A 67-year-old man presented with a 15-year history of a painful, slow growing 3 × 3.5 cm sized mass in the subcutis of his right lateral thigh. Histopathological studies showed a subcutaneous mass entirely within the lumen of a vein. The tumor was composed of spindle-shaped myoid-appearing cells in a concentric arrangement, intimately associated with thin-walled vascular channels. Tumor cells were diffusely positive for smooth muscle actin, focally positive for CD34, and negative for desmin and CD31. From these findings, we diagnosed this lesion as intravascular myopericytoma. Unlike previous reports, our case showed a relatively large painful subcutaneous mass, although this tumor has an intravascular nature.