Renal angiomyolipomas were present in 23 out of a series of 38 patients with 
proven tuberous sclerosis (60.5%). Multiplicity and bilateral localization of 
combined renal angiomyolipomas were important differences between this category 
and the isolated, usually solitary, angiomyolipomas. One of the parents of a 
patient with tuberous sclerosis had small renal angiomyolipomas without signs of 
tuberous sclerosis. This indicates that renal angiomyolipomas might be a forme 
fruste of tuberous sclerosis. Two patients with suspected isolated renal 
angiomyolipomas proved to have tuberous sclerosis. From this study we can 
conclude that multiple angiomyolipomas, or a combination of a single renal 
hamartoma with one of the signs suggestive of tuberous sclerosis, warrant a 
thorough examination to exclude tuberous sclerosis.