Melanotic schwannoma.

Reports of melanotic nerve sheath tumors of Schwann cell origin are rare, only three having been found in the literature. Two new cases of spinal intradural melanotic nerve sheath tumors are reported and the literature is reviewed. Controversy has arisen in regard to the origin of melanin within these tumors. Electron microscopic study of one of our cases indicates that the Schwann cell is capable of producing melanin. The available evidence suggests that ultrastructural identification of the cell type in these pigmented tumors is essential in plotting the therapy and prognosis of patients with melanotic nerve sheath tumors.