Hypomelanosis of Ito and hemimegalencephaly.

Hypomelanosis of Ito is a congenital neurocutaneous syndrome with a particular pattern of swirling hypopigmentation. Multiple extracutaneous abnormalities involving the central nervous system, the eyes, and musculoskeletal structures occur in over two-thirds of the cases. This report describes two patients with typical unilateral cutaneous lesions associated with extracutaneous features, including hypertrophy of the cerebral hemisphere contralateral to the cutaneous hypopigmentation. Magnetic resonance imaging and EEG findings support the diagnosis of hemimegalencephaly, as has recently been reported in other isolated cases of this rare phakomatosis.