Primary Spinal Melanoma With Intra- and Extradural Extensions: A Rare Case

Primary spinal melanoma (PSM) is a rare primary central nervous system melanoma with limited literature. A 30-year-old male presented with one year of progressive bilateral leg weakness and back pain. Physical examination revealed slightly decreased power and deep tendon reflexes of the lower extremities, decreased sensation at the level of T10, and normal anal sphincter and plantar reflexes. Magnetic resonance imaging (MRI) scan of the thoracolumbar spine revealed a hypointense lesion on T2-weighted and a hyperintense lesion on T1-weighted imaging at the level of T10 with mild extensions. The lesion was causing a mass effect on the spinal cord. The patient underwent laminectomy and near-total excision which showed a black, firm-to-hard, scarcely vascular extradural tumor extending from T10 to T11 that adhered to nerve roots. Histopathological examination and immunostaining with S-100 and Melan-A stains confirmed the diagnosis of malignant melanoma. Other imaging studies like brain computed tomography (CT) and positron emission tomography/computed tomography (PET/CT) scans, and chest X-ray were normal. On follow-up, the patient reported improvement in the power of his lower limbs with intact sensory function and sphincters. The first radiotherapy session was scheduled for six weeks postoperatively. There was no recurrence at a two-year follow-up. The possibility of a melanocytic tumor should be considered for a spinal lesion with paramagnetic properties as early surgical intervention is important for diagnosis and improved survival.