Neurofibromatosis Type 1-Associated Multiple Malignant Peripheral Nerve Sheet Tumors: A Case Report and Literature Review

Background: Neurofibromatosis type 1 (NF-1) is a genetic disorder characterized by café-au-lait macules, freckling, Lisch nodules, and neurofibromas. NF-1 patients have a special predisposition to tumorigenesis due to genetic mutations, affecting the tumor regulator systems. Malignant Peripheral Nerve Sheet Tumor (MPNST) is a highly aggressive soft tissue tumor that is usually associated with NF-1. Case presentation: A 32-year-old woman was presented complaining of weakness, severe fatigue, weight loss, peripheral paresthesia, progressive generalized myalgia, bone pain, and a mass sensation in her right thigh since three months ago. She was a known case of NF-1 since childhood. After clinical and radiological evaluation, multiple masses were detected in the retroperitoneal cavity adjacent to the left kidney, uterus, and right thigh. Finally, the patient was planned for surgical excision of two masses with subsequent chemotherapy. Both excised masses were confirmed as MPNSTs by histopathological examination. Conclusion: Regarding the predisposition of NF-1 patients to tumorigenesis and the high prevalence of peripheral nerve tumors among these patients, any masses changing their character should raise suspicion for malignancy. One of the serious malignant lesions is MPNST. The primary treatment plan for these malignant lesions is surgical excision with subsequent chemotherapy or radiotherapy based on individual characteristics.