This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Neurocutaneous melanosis (NCM) is a rare, non-inherited condition of the central nervous system. It is characterized by melanocytic nevi in both the skin and the brain. Two-thirds of people with NCM have giant congenital melanocytic nevi, and the remaining one-third have numerous lesions but no giant lesions. The typical cutaneous lesions are present at birth. Neurological features typically present in the first or second year. Intracranial hypertension is the most common presentation, along with seizures, decreased alertness, and cranial nerve dysfunction.The underlying cause, while not completely understood, is believed to be a primary defect in the neural crest.
Management depends on the symptoms present, and may include close observation, shunting to reduce intracranial pressure. The prognosis of patients with symptomatic neurocutaneous melanosis is generally poor, even in the absence of malignancy. Chemotherapy has been ineffective in the few patients in whom it has been tried.
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