Neurocutaneous melanocytosis (Q93770)

Neurocutaneous melanocytosis (NCM) is a rare congenital neurological disorder characterised by abnormal aggregations of naevomelanocytes within the central nervous system (leptomeningeal melanocytosis) associated with large or giant congenital melanocytic naevi (CMN; see this term). NCM can be asymptomatic or present as variably severe and progressive neurological impairment, sometimes resulting in death. Prevalence is estimated at 1/50,000-1/200,000. The incidence of symptomatic NCM appears to be approximately a third to a half of these.