Melanoma arising in a spinal nerve root. Case report.

Melanotic neoplasms of the spinal nerve root are rare but well-documented occurrences. The authors report the case of a 68-year-old woman with a malignant melanotic neoplasm containing premelanosomes and melanosomes and lacking a basal lamina. This tumor was found in a lumbar nerve root and is believed to represent an instance of a primary melanoma arising in a spinal nerve root. The differential diagnosis of pigmented lesions of spinal nerve root includes melanoma, pigmented nerve sheath tumor, blue nevus, melanotic clear-cell sarcoma, and meningeal melanocytoma. Surgeons should be aware of the potential for encountering unexpected malignant lesions involving spinal nerve roots.