Malignant peripheral nerve sheath tumor of the infratemporal fossa: Case report and literature review

Introduction: Malignant peripheral nerve sheath tumor (MPNST) is rare soft tissue sarcoma that arises from a peripheral nerve or shows nerve sheath differentiation. Case Report: We present a case of a 43-year-old female diagnosed with neurofibromatosis type 1 and with a plexiform neurofibroma of the infratemporal fossa (IF) evolving for about four years. Examination revealed facial asymmetry with the prominence of the right hemiface, without facial pain, motor deficits or facial numbness. The magnetic resonance imaging (MRI) showed a lesion in right IF with well-defined limits and 18F-FDG positron emission tomography/computed tomography (PET/CT) showed intense metabolism that was attributed to malignant transformation. Cytology confirmed a MPNST. Excision of the IF lesion by maxillary swing approach was performed. The anatomopathological evaluation of the lesion revealed a 7×6×3 cm high grade MPNST arising within a neurofibroma. The excision was juxtalesional. The tumor was staged at pT3cN0M0, IIIB. The patient underwent adjuvant radiotherapy. Currently, after 12 months of follow-up, the patient is asymptomatic, without neurologic deficits. The MRI performed three months after the end of radiotherapy shows no evidence of tumor recurrence. Conclusion: The only known definitive curative treatment for MPNST is complete surgical resection with wide negative margins. The maxillary swing approach delivers wide tumor exposure, providing controlled dissection with minimizing morbidity. Despite maximal efforts, MPNSTs are usually highly aggressive. Increased tumor size and high-grade morphology, features which were observed in our patient, have been identified as factors that negatively affect long-term survival. We encourage a multidisciplinary approach in the management of these rare tumors to optimize outcomes.