19 - Melanocytic Neoplasms of the Central Nervous System

Melanocytic neoplasms of the central nervous system (CNS) arise from leptomeningeal melanocytes present within the arachnoid membranes. Lesions can manifest as diffuse disseminations within the subarachnoid space or as solid masses, and they range in histologic grade from benign to malignant. Meningeal melanocytoma (benign mass forming proliferation), meningeal melanoma (malignant mass forming proliferation), meningeal melanocytosis (diffuse meningeal benign melanocytic proliferation), and meningeal melanomatosis (diffuse meningeal malignant melanocytic proliferation) belong in this category of diseases.¹ The term neurocutaneous melanosis refers to a group of rare genetic disorders that combine giant single and/or numerous smaller congenital nevi with diffuse leptomeningeal melanosis and increased risks of malignant transformation to melanoma.