Benign triton tumor of the trigeminal nerve

Benign triton tumor (neuromuscular hamartoma) is a rare tumor of the periph eral nerves, comprising mature neural and striated muscle elements. We repo rt the third case, according to the literature, of a benign triton tumor af fecting the Vth cranial nerve in a 4-year old male child. The tumor was see n to involve the mandibular division of the trigeminal nerve in the infrate mporal fossa and extend intracranially by eroding the base of middle crania l fossa. The mass was totally excised. In the tumor, bundles of axons inter mingling with fascicles of relatively mature skeletal muscle were found. Th is type of hamartomatous lesions of neuroectodermal-mesenchymal origin coul d have arisen as the result of incorporation of mesenchymal tissue into ner ve sheaths during embryogenesis or aberrant differentiation of neuroectoder mal component into mesenchymal elements.