Sebaceous nevus syndrome: report of two cases.

Sebaceous nevus (SN) syndrome is a neurocutaneous disorder characterized by a distinctive skin lesion in association with epilepsy and mental retardation. In one group of patients, brain lesions may be consequent to vascular abnormalities ("vascular variant"); another group of SN patients presents ipsilateral hemimegalencephaly, gyral anomalies, and facial hemihypertrophy ("neurologic variant" or "SN with hemimegalencephaly"). In the latter group, facial hemihypertrophy does not appear to be a constant feature and was not present in our 2 SN patients with hemimegalencephaly. Considering that about half of the SN patients with hemimegalencephaly described so far do not have facial asymmetry, we suggest the existence of a separate subgroup of SN patients with hemimegalencephaly and without facial hemihypertrophy. In these patients, the only clinical diagnostic clue is a nevus that is barely visible until puberty.