Central Nervous System Involvement and Neuroradiological Imaging Insights of Neurocutaneous Melanocytosis in Congenital Melanocytic Nevi.

Congenital melanocytic nevi (CMN) are pigmented lesions present at birth, varying widely in size and clinical impact. In rare instances, these nevi become visible during the first months of life, a phenomenon known as tardive melanocytic nevi (tardive CMN). Giant congenital melanocytic nevi (GCMN) are defined as nevi larger than 40 cm in projected adult size (PAS). Their association with the central nervous system (CNS) poses significant risks, including melanoma and neurocutaneous melanocytosis (NCM), where melanocytes infiltrate the CNS, potentially causing seizures, hydrocephalus, and, rarely, CNS melanoma. MRI is recommended for GCMN patients, particularly those with numerous satellite nevi or neurological symptoms, to detect CNS involvement. The Nevosurgery Network recommends MRI examinations in cases of GCMN (>40 cm PAS), the presence of over 20 concomitant nevi, and neurological symptoms requiring clarification. CMN can be associated with melanocyte accumulations and melanin deposits in the brain, spinal cord, and leptomeninges. [ABSTRACT FROM AUTHOR]