[A case of "forme fruste" of tuberous sclerosis having been treated as genuine epilepsy].

A 30-year-old man had signs of a lumbosacral skin plaque, called "shagreen patch", and mental retardation. He had been treated as genuine epilepsy for more than twenty years. Neither significant abnormalities nor facial angiofibroma (adenoma sebaceum) were detected on physical and neurological examinations. Brain CT revealed calcified subependymal nodules. A T2-weighted brain MRI presented high signal intensity regions affecting the cerebral cortex, which suggested tuberous lesions. Echocardiography showed high echoic lesions on the left ventricular wall and papillary muscles, suggesting calcification. The case was diagnosed as suffering from "forme fruste" of tuberous sclerosis. The three criteria typical of tuberous sclerosis (facial angiofibroma, seizure and mental retardation) were not satisfied. The "forme fruste" variant is less known, because the pattern of involvement varies, and it may clinically simulate genuine epilepsy.