Malignant peripheral nerve sheath tumor of the sciatic nerve presenting with leg pain in the setting of lumbar scoliosis and spinal stenosis.

Case report.We present a case of malignant peripheral nerve sheath tumor (MPNST) presenting as neuropathic pain in the setting of lumbar scoliosis and spinal stenosis. Most peripheral nerve sheath tumors are benign, and malignant cases are more commonly associated with neurofibromatosis type 1 or prior radiation exposure. MPNST is a rare tumor with a poor prognosis. We report a case of MPNST that presented as neuropathic pain following lumbar decompression and fusion surgery.A 60-year-old woman presented for management of lumbar scoliosis, stenosis, and left leg pain. After lumbar decompression and fusion surgery, the patient was readmitted to the hospital after falling 10 weeks post-op. She reported gradual recurrence of leg pain. Left foot drop was noted on exam. Imaging studies showed no spinal changes postoperatively or residual stenosis. Obesity limited electrodiagnostic studies. Hip MRI revealed a lobular soft tissue mass in the left sciatic notch. Surgical resection and pathology provided the diagnosis of MPNST. The patient declined wide resection and other interventions after seeking a second opinion. Palliative pain management was implemented.The patient expired 15 months after her index spinal surgery.MPNST is an extremely rare tumor that can present with symptoms similar to radiculitis. Clinical signs and symptoms of MPNST are vague and nonspecific due to compression of surrounding structures. Surgical wide resection is the first line of treatment for MPNST with chemotherapy and radiotherapy as adjuvant treatments. MPNST has a poor prognosis with reported 5-year survival ranging from 16 to 54%. This case demonstrates the need to pursue additional workup when diagnostic imaging and objective findings do not satisfactorily explain the clinical presentation.IV.