A 21-year-old woman with tuberous sclerosis presented with abdominal disten
sion and flank pain. Imaging studies, including CT and MR imaging, revealed
bilateral renal mass lesions, containing fat and suggesting the diagnosis
of tuberous sclerosis. However the imaging characteristics of one of these
lesions differed from the others with no radiologically detectable fat tiss
ue in this solid lesion suggesting renal cell carcinoma. Histopathological
examination of this lesion in the left kidney revealed an angiomyolipoma wi
th minimal fat tissue. The radiological diagnosis of angiomyolipomas with m
inimal fat tissue remains difficult and the differential diagnosis is discu
ssed.