[Primary intramedullary melanocytoma of medulla oblongata: a case report].

A case of intramedullary melanocytoma of the medulla oblongata; which has not been hitherto reported, is presented. The tumor ran on a slow progressive course. The patient died of pneumonia seven months after the operation. MRI findings did not specify this tumor as they were not distinct from those of malignant melanoma. The tumor was totally black and was not attached to the dura. Microscopically, the neoplastic cells were uniform in size and possessed abundant melanin granules in their cytoplasm. Mitosis was very rare. The ultrastructure of the tumor cells showed many melanosomes at varying stages of maturation. The melanocytoma in the eloquent region has an unfavorable outcome.