Preoperative diagnosis of renal angiomyolipoma.

Six cases of renal angiomyolipoma are reviewed. In 5 of these 6 cases a characteristics radiolucent fat sign was present overlying the renal mass. In 10 cases of hypernephroma selected only on the basis of a tissue diagnosis and the availability of a pre-injection scout film this sign was not present. The recent literature is reviewed on the radiographic diagnosis of angiomyolipoma. We conclude that angiography is not reliable in the differentiation of angiomyolipoma from hypernephroma. However, demonstration of a radiolucency on the pre-injection scout film is virtually pathognomonic of angiomyolipoma. Tomographic cuts without contrast injection may increase diagnostic accuracy.