ABSTRACT
Arising from the melanocytes within the leptomeninges, primary melanocytic tumors consist of meningeal melanocytosis, melanomatosis, melanocytoma, and melanoma. Meningeal melanocytosis is a diffuse infiltration of the subarachnoid space of the brain and spinal cord by melanocytes, possibly associated with neurocutaneous melanosis. Meningeal melanomatosis is the malignant form of diffuse involvement resulting from the spread of malignant melanocytes into the leptomeninges and Virchow-Robin spaces with superficial invasion of the brain. Meningeal melanocytoma is a rare, pigmented, slow-growing, and typically benign neoplasm that may sometimes show malignant behavior. Melanocytes are melanin-producing cells that originate from the neural crest during early embryogenesis and that develop mainly in the skin but occasionally in the eye, mucous membranes, or the central nervous system (CNS). Melanocytic tumors of the CNS demonstrate overlapping histological characteristics but show distinct biological behavior. Clinically, meningeal melanocytosis may cause hydrocephalus, mass effect, and neuropsychiatric symptoms, which resemble those of neurocutaneous melanosis and congenital nevi.
