Malignant peripheral nerve sheath tumors of the trigeminal nerve: A systematic review of 36 cases

Object: Malignant peripheral nerve sheath tumors (MPNSTs) are a rare form of malignancy arising from the Schwann cells of peripheral nerves. MPNSTs of the trigeminal nerve are exceptionally rare, with only a handful of reports in the literature. These tumors are typically very aggressive, resulting in significant patient morbidity and a generallygrim prognosis. Most current reports suggest that radical resection with radiation therapy offers the best benefit. In this study, the authors systematically reviewed the world English-language literature onMPNSTs of the trigeminal nerve to analyze the presentations, treatment options, and outcomes for patients with this disease. Methods: A literature search for MPNSTs of the trigeminal nerve confined to nonanimal, English-language articles was conducted utilizing the PubMed database, with additional cases chosen from the references of selected articles. Only cases of confirmed MPNSTs of the trigeminal nerve or its peripheral branches, based upon surgical, pathological, or radiological analysis, were included. ResultsL: From the literature search, 29articles discussing 35 cases of MPNSTs of the trigeminal nerve were chosen. With the addition of 1 case from their own institution, the authors analyzed 36 cases of trigeminal MPNSTs. The average age of onset was 44.6 years. These tumors were more commonly seen in male patients (77.1%). The gasserian ganglion was involved in 36.1% of the cases.Of the cases in which the nerve distribution was specified (n = 25),the mandibular branch was most commonly involved (72.0%), followed bythe maxillary branch (60.0%) and the ophthalmic branch (32.0%), with 44.0% of patients exhibiting involvement of 2 or more branches. Altered facial sensation and facial pain were the 2 most commonly reportedsymptoms, found in 63.9% and 52.8% of patients, respectively. Mastication difficulty and diplopia were seen in 22.2% of patients, facial weakness was seen in 19.4%, and hearing loss was present in 16.7%. With regard to the primary treatment strategy, 80.6% underwent resection,16.7% underwent radiation therapy, and 2.9% received chemotherapy alone. Patients treated with complete resection followed by postoperative radiation therapy had the most favorable outcomes, with no patients showing evidence of disease recurrence with a mean follow-up of 34.6 months. Patients treated with incomplete resection followed by postoperative radiation therapy had more favorable outcomes than patientstreated with incomplete resection without radiation therapy or radiation therapy alone. Conclusions: Trigeminal MPNSTs most commonly present as altered facial sensation or facial pain, although they exhibit a number of other clinical manifestations, including the involvement of other cranial nerves. While a variety of treatment options exist, due to their highly infiltrative nature, aggressive resection followed by radiation therapy appears to offer the greatest chance of recurrence-free survival.