[Spinal melanocytic schwannoma with malignant course. Microscopic and ultrastructural study of a case]

The authors report a case of recurrent pigmented intraspinal schwannoma with malignant progression. Electron-microscopic study confirmed that melanin pigment was produced by tumor cells and that these cells were derived from the nerve sheath. The histogenesis of pigmented tumors is explained by their neural crest origin and the problem of differential diagnosis of the malignant form with melanoma is discussed.