Primary melanoma of the central nervous system

Primary melanoma of the central nervous system (also known as primary CNS melanoma or primary meningeal melanoma) is an extremely rare malignant tumor that arises from melanocytes residing within the leptomeninges (the thin membranes covering the brain and spinal cord). Unlike metastatic melanoma that spreads to the brain from a skin primary site, this tumor originates directly within the central nervous system without evidence of a cutaneous or extracranial primary melanoma. It accounts for approximately 1% of all melanoma cases and about 0.07% of all brain tumors. The disease primarily affects the meninges but can involve the brain parenchyma and spinal cord. Symptoms depend on the tumor's location and may include headaches, seizures, focal neurological deficits (such as weakness, sensory changes, or visual disturbances), signs of increased intracranial pressure, hydrocephalus, and cognitive or behavioral changes. Spinal lesions may present with back pain, radiculopathy, or progressive myelopathy. The tumor can present as a solitary mass or as diffuse leptomeningeal melanomatosis, the latter carrying a particularly poor prognosis. Treatment typically involves maximal safe surgical resection when feasible, often followed by adjuvant radiation therapy. The role of chemotherapy has historically been limited, though newer approaches including targeted therapies (for tumors harboring BRAF or NRAS mutations) and immune checkpoint inhibitors (such as nivolumab and ipilimumab) are being explored based on extrapolation from cutaneous melanoma treatment paradigms. Despite treatment, prognosis remains generally poor, particularly for diffuse forms, with median survival often reported at less than two years. Early diagnosis and complete surgical resection, when achievable, are associated with better outcomes.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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