Figure 3b. Bilateral renal sinus lipomatosis in a 76-year-old asymptomatic man. (a) Excretory urogram shows diffuse elongation and attenuation of the renal pelvis and infundibula of both kidneys. (b) Axial contrast-enhanced CT scan shows proliferation of fat (arrows) in both renal sinuses, a finding suggestive of renal sinus lipomatosis.