Benign triton tumor: multidisciplinary approach to diagnosis and treatment

Benign Triton tumor (neuromuscular choristoma) is a rare mass that most commonly occurs as a multinodular expansion of tissue in or around large nerves. Intracranial occurrence is uncommon. We report on a 4-year-old girl presenting with a right-sided facial mass and trismus. Imaging revealed a large, complex mass extending from the ventral aspect of the pons, along the trigeminal nerve, through the foramen ovale, and into the right infratemporal fossa. The lesion was partially enhancing, invaded adjacent infratemporal musculature, was associated with marked overgrowth of the right coronoid process, and induced bony erosion of the middle cranial fossa. After needle biopsy, a multidisciplinary team, including plastic surgery, otolaryngology, and neurosurgery, performed a combined, multistep, single-day surgical approach for resection. Unique to this case was the resection of the coronoid process, a modified middle fossa intradural and extradural approach, coupled with a transfacial infratemporal approach. Microscopically, the resected tissue showed skeletal muscle, fibrous tissue, and nerve in a disorganized arrangement characteristic of a benign Triton tumor. We present this case to illustrate diagnostic clues and pitfalls in the preoperative evaluation of a benign Triton tumor. We also highlight the pathologist's role as a partner in a multidisciplinary approach to diagnosis and treatment of this rare pediatric mass, potentially the largest Triton tumor in the head reported to date.