[CT appearance of small renal angiomyolipoma]

Twenty-six small renal angiomyolipomas (AML) in 21-patients, detected incidentally by ultrasonography, were evaluated with CT. Conventional CT findings of AML were classified into three types by the degree of the fatty areas in the mass. Type 1 is a mainly fat density mass like a lipoma observed in 7 lesions (26.9%). Type 2 is a fatty mass intermixed with areas of tissue density and found in 15 lesions (57.7%). Type 3 is a mass without fatty portion and observed in 4 lesions (15.4%). These latter lesions were indistinguishable from renal cell carcinoma on CT. It is important to diagnose a small lesion of the kidney as AML correctly for proper treatment.