Epidermal naevus syndrome

A neurocutaneous disorder in which epidermal nevi are associated with multiple anomalies affecting mainly the central nervous and skeletal systems. The nevi are generally present at birth and subsequently undergo pigmentary and verrucous changes, having special predilection for the face and scalp and extending to other organs. Seizures and mental retardation complicate the neurological abnormalities. Hemimegaloencephaly with ipsilateral gyral malformations, seizures, infantile spasms, facial hemihypertrophy, and Dandy-Walker malformation (absence of the cerebellar vermis, hydrocephalus, and posterior fossa cyst continuing with the fourth ventricle) occur in some cases.