Tuberous sclerosis is a phakomatosis with central nervous system manifestations characterized by 4 lesions detectable on neuro-imaging: tubers, white matter abnormalities, subependymal nodules and subependymal astrocytomas. The first three are benign lesions composed of by identical cytological lesions varying only in size and location. At CT, enhancement of subependymal nodules is usually considered as evidence of transformation to subependymal giant cell astrocytoma. This latter poses the problem of its relative benignity: hydrocephalus source of morbidity or even mortality. From a series of 22 cases, the authors review the characteristics of these abnormalities.