RARE-10. Neurocutaneous melanocytosis-associated hydrocephalus: the MSK experience from 2001-2022

OBJECTIVE: We hypothesize that patients with neurocutaneous melanocytosis-associated melanoma and ventriculoperitoneal shunts are at risk of developing intraperitoneal spread of melanoma. BACKGROUND: Neurocutaneous melanocytosis, a rare condition characterized by excessive proliferation and deposition of melanocytes in the leptomeninges and brain parenchyma, typically occurs in children with large congenital melanocytic nevi and multiple smaller congenital nevi. These patients are at heightened risk for developing NRAS+ melanomas in the central nervous system, which in turn may lead to symptomatic hydrocephalus requiring cerebrospinal fluid diversion for symptom relief. METHODS: Retrospective single-institution study of patients with histologically or radiographically confirmed NCM evaluated at Memorial Sloan Kettering Cancer Center (MSKCC) from 2001-2022. RESULTS: Of the 47 patients with a diagnosis of NCM, 44 patients had symptomatic neurological complications. Eleven patients developed hydrocephalus, 10 had CNS melanoma, and required ventriculoperitoneal shunt placement. Nine of the 10 patients ultimately died of their disease. Three patients were diagnosed with intraperitoneal melanoma, though data are unavailable for the remaining eight. CONCLUSIONS: All (n=11) patients with NCM-associated CNS melanoma required VP shunts for symptomatic relief. Ten of these patients died within 4.3 years of VP shunt placement, with a range of 1 month to 13.5 years prior to succumbing to their disease. While the intraperitoneal pathology remains unknown for 7 of the cases, 3 had confirmed intraperitoneal melanoma, suggesting that VP shunts provided the conduit to CNS melanoma seeding of the peritoneum. Obtaining baseline abdominal imaging studies prior to VP shunt placement may be helpful in the follow-up of these patients.