Melanotic schwannoma arising in the floor of the mouth

Melanotic (pigmented, melanocytic) schwannoma is a relatively rare neoplasm that arises in a spinal nerve root.(1) Most histologic characterizations of this tumor have reported diffuse melanin pigmentation.(2,3) The tumor has been associated with aggressive behavior,(4) and many investigators have proposed that it probably has malignant potential because previous reports have shown that recurrences are frequent.(1,4-6) However, only a few cases have been reported in an oral region, and therefore it is difficult to predict its prognosis in this region because of the small number of reported cases. We now report a rare case of a benign melanotic schwannoma arising in the floor of the mouth. Its immunohistochemical and ultrastructural characteristics are also examined.