CT Differentiation of Large Exophytic Renal Angiomyolipomas and Perirenal Liposarcomas

OBJECTIVE. The purpose of our study was to describe the imaging findings and CT characteristics that lead to accurate distinction of large exophytic renal angiomyolipomas from retroperitoneal perirenal liposarcomas, which at times can be confused on imaging studies and even at pathologic examination.MATERIALS AND METHODS. We retrospectively analyzed CT images of 15 large exophytic renal angiomyolipomas and 12 well-differentiated perirenal liposarcomas. Pathologic correlation was available for six of 15 angiomyolipomas and all of the liposarcomas. All examinations were evaluated for lesion size, renal parenchymal defect, enlarged vessels, kidney displacement, lesion encapsulation or margination, associated hemorrhage, and additional angiomyolipomas. The records of patients with tuberous sclerosis or the forme fruste of that condition were excluded from the study.RESULTS. The average size of the angiomyolipomas was 14 × 10 cm. They showed a renal parenchymal defect (n = 15), enlarged vessels (n = 12), renal...