Renal myopericytoma: case report and review of literature.

Myopericytoma arising in the visceral organs is rare and only 1 case of renal myopericytoma has been reported in the literature to date. We report the second case of myopericytoma arising in the kidney in a 40-year-old Hispanic woman who presented with pain on the left side of the abdomen and frequent urination. Abdominal computed tomography scan showed an exophytic left-sided renal mass. Partial nephrectomy was performed. The patient remains free of disease at 24 months after diagnosis. Our case is histologically distinct from the previously described case as it lacks the "hemangiopericytic/glomangiopericytoma" pattern. The tumor in our case showed the characteristic pattern of myopericytoma and an additional glomus tumorlike pattern. The tumor cells showed diffuse reactivity for vimentin, smooth muscle actin, smooth muscle myosin heavy chain, and muscle-specific actin in both morphologic patterns and strong diffuse CD34 expression in glomus tumorlike focus. This case report adds to the morphologic heterogeneity of myopericytomas.