Neurocutaneous melanocytosis

Neurocutaneous melanocytosis (NCM) is a rare congenital neurological disorder characterized by abnormal aggregations of nevomelanocytes within the central nervous system (leptomeningeal melanocytosis) associated with large or giant congenital melanocytic nevi (CMN; see this term). NCM can be asymptomatic or present as variably severe and progressive neurological impairment, sometimes resulting in death.