Abstract

Extrarenal retroperitoneal angiomyolipomas (AML) are extremely rare, therefore they may present a diagnostic challenge. In this paper, the authors describe a case of a huge retroperitoneal AML in a 49-year-old woman who presented with sudden abdominal pain. Computed tomography revealed the presence of a large, round, fatty mass in the retroperitoneal space, which was easily removed by surgery. The mass was well encapsulated and dark yellow on the cut surface. Microscopically, the tumor was exclusively composed of adipose tissue with frequent multivacuolated, lipoblast-like cells masquerading as well differentiated liposarcoma. In addition, there were many clear, epithelioid cells present, especially around the small blood vessels, which were reactive for HMB-45 and smooth muscle actin.

• Keywords: Angiomyolipoma;Liposarcoma;Retroperitoneal neoplasms