MR imaging of symptomatic neurocutaneous melanosis in children.

Neurocutaneous melanosis is a syndrome consisting of cutaneous nevi and melanocytosis of the leptomeninges. Over a 5-year period (1989-1994) we evaluated with MR imaging the central nervous system of five children with a confirmed histologic diagnosis of neurocutaneous melanosis. The children ranged in age from 7 to 10 years and consisted of two girls and three boys. They all had multiple pigmented skin lesions (cutaneous nevi) and presented with seizures, signs of raised intracranial pressure, cranial nerve palsies and/or myelopathy. The MR studies were performed with T1-weighted, T2-weighted and T1-weighted post-gadolinium images of the brain in addition to T1-weighted post-gadolinium images of the entire spine. The MR findings in all the children consisted of marked, diffuse enhancement of thickened leptomeninges surrounding the brain and spinal cord which was only demonstrated on the post-gadolinium T1-weighted images and mild to moderate hydrocephalus. We present our MR findings and compare these findings with other imaging findings in the literature. Our findings represent part of a spectrum of imaging abnormalities seen in patients with neurocutaneous melanosis.