[Extrarenal retroperitoneal angiomyolipoma: description of a case and review of the literature].

A case of retroperitoneal extrarenal angiomyolipoma is described. The patient, a 61-year-old woman, presented with a large retroperitoneal lipomatous mass. Histologically, it consisted of lipomatous tissue. Focally, there was interstitial and perivascular proliferation of bland oval and epithelioid cells with a large, eosinophilic or clear cytoplasm. Immunohistochemically, these elements were positive for smooth muscle actin and HMB-45. The literature on retroperitoneal extrarenal angiomyolipoma is briefly reviewed. It is important that the pathologist recognize this lesion, even when it is located in the retroperitoneum outside the kidney, and differentiate it from a liposarcoma.