Background: Patients with a large congenital melanocytic nevus (LCMN) may have associated leptomeningeal melanocytosis with or without central nervous system (CNS) melanomas. These patients are considered to have neurocutaneous melanosis, a disorder that, when symptomatic or otherwise manifest neurologically, carries a poor prognosis even in the absence of malignancy.
Objective: Our purpose was to identify typical clinical features in patients who have manifest CNS melanosis in association with LCMN.
Methods: The records of 117 patients with LCMN in the New York University Registry of LCMN and the reports of 172 cases of LCMN in the world literature were included for features that might signal a high risk for the development of manifest CNS involvement.
Results: Of the 289 patients with LCMN, 33 had manifest CNS melanosis. In all 33 in whom symptomatic neurocutaneous melanosis was diagnosed, the LCMNs were present in a posterior axial location on the head, neck, back, and/or buttocks. "Satellite" nevi were known to be present in 31 of the 33 patients.
Conclusion: Patients with LCMN in a posterior axial location, especially when associated with "satellite" melanocytic nevi, are at greater risk for the development of manifest neurocutaneous melanosis than patients with LCMN limited to the extremities or those who are lacking satellite nevi.