Epithelioid angiomyolipoma associated with a classic angiomyolipoma

We report a case of renal epithelioid angiomyolipoma that arose in association with a classic angiomyolipoma in a 54-year-old Japanese man without tuberous sclerosis. Histologically, the tumor was composed of polygonal cells exhibiting diffuse hemorrhage, multifocal necroses, and vascular invasion. Immunohistochemical staining was positive for melanoma specific antibody and focally positive for smooth muscle actin. On the basis of a review of the literature, we suggest that large epithelioid angiomyolipoma may have malignant potential and therefore requires close follow up.