Intramedullary primary spinal cord melanoma: illustrative case.

[BACKGROUND] Intramedullary primary spinal melanoma (IPSM) is a rare tumor, with limited reports on its clinical presentation, radiographic features, histopathological and genetic factors, diagnosis, and management.

[OBSERVATIONS] A 49-year-old male presented with a 9-month history of intermittent, progressive left upper-extremity radiculopathy and left-sided numbness. Magnetic resonance imaging revealed an intramedullary tumor at the C6-T1 vertebral levels. Intraoperatively, upon opening the dura, the tumor was noted to be dark in appearance. Dorsal column mapping allowed for safe myelotomies above and below the tumor bulk, and a gross-total resection was achieved. The patient awoke with mild decreased lower-extremity sensation and proprioception but full motor strength. Surgical pathology was consistent with melanoma. Further workup ruled out the possibility of alternative primary neoplastic sites, and a diagnosis of IPSM was made. The patient was planned for radiation therapy (RT) and immune checkpoint inhibitor therapy in follow-up.

[LESSONS] Fewer than 40 cases of IPSM have been described in the literature. While patients with IPSM present with progressive symptomology and unique imaging findings, surgical pathology is required for a diagnosis. The optimal treatment paradigm likely includes resection, RT, and/or systemic therapies. Molecular and genetic markers might enable more efficient diagnosis and optimize therapy for these patients. https://thejns.org/doi/10.3171/CASE24732.