Malignant peripheral nerve sheath tumor

Malignant peripheral nerve sheath tumor (MPNST), also known as neurofibrosarcoma or malignant schwannoma, is a rare and aggressive soft tissue sarcoma that arises from cells of the peripheral nerve sheath, including Schwann cells, perineural cells, or fibroblasts associated with peripheral nerves. These tumors can develop anywhere along peripheral nerves in the body but most commonly occur in the extremities, trunk, and head and neck region. MPNSTs account for approximately 5-10% of all soft tissue sarcomas and are strongly associated with neurofibromatosis type 1 (NF1), with roughly half of all cases occurring in individuals with this inherited condition. In NF1 patients, MPNSTs frequently arise from pre-existing plexiform neurofibromas that undergo malignant transformation. Key clinical features include a rapidly enlarging mass, pain, neurological deficits such as numbness, weakness, or tingling in the affected area, and sometimes changes in a pre-existing neurofibroma (rapid growth, new pain, or change in texture). MPNSTs are high-grade tumors with a significant propensity for local recurrence and distant metastasis, most commonly to the lungs, bone, and liver. The prognosis is generally poor, with five-year survival rates ranging from approximately 20-50% depending on tumor size, location, grade, and resectability. The primary treatment for MPNST is wide surgical resection with clear margins, which remains the cornerstone of therapy. Adjuvant radiation therapy is frequently employed to reduce the risk of local recurrence, particularly when surgical margins are close or positive. The role of chemotherapy remains debated, though doxorubicin-based and ifosfamide-based regimens are sometimes used in the neoadjuvant or adjuvant setting, or for metastatic disease. Targeted therapies and immunotherapies are under active investigation in clinical trials. Genetic alterations commonly found in MPNSTs include loss of NF1 gene function, inactivation of the CDKN2A/p16 tumor suppressor, and loss of polycomb repressive complex 2 (PRC2) components SUZ12 and EED, which are being explored as potential therapeutic targets.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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