Malignant Peripheral Nerve Sheath Tumor of Non-Neurofibromatosis Type I Metastasized to the Cerebrospinal Axis
An 18-year-old man presented initially with a 6-month history of low back pain that worsened over time. One month prior to admission, the patient developed radiating pain to his anterior thigh. Neither Café au lait spots nor neurofibromas were seen and his family history was absent of NF-1.\nThe neurologic examination showed normal motor power in his lower extremities. Magnetic resonance imaging (MRI) showed a paraspinal mass that extended from the central space of L2 to the right psoas muscle through right L2-3 foraminal space. It was an asymmetrical dumbbell shaped mass and the thecal sac was displaced left by the mass. The mass showed iso-signal intensity on T1-weighted images and mixed signal intensity on T2-weighted images. Strong enhancement was visible after gadolinium injection (). There was no evidence of bony erosion.\nThe patient underwent surgery using a posterior approach. A paramedian incision was made from the L1 to L4 and we exposed the right L2 and L3 lamina with transverse process. Right L2 hemilaminectomy was performed using a high speed drill and kerrison rongeur to expose the thecal sac. For removal of intradural portion, the thecal sac was incised. The mass was soft and slightly reddish. The margin of mass was relatively distinct from neural tissue, thus gross total resection was possible under microscopic view. To remove the mass extended to the psoas muscle, the right transverse process of L2 and L3 was resected and the mass was visible. Piecemeal resection of the mass was performed and gross total resection was achieved. Frozen biopsy was reported as schwannoma.\nAfter the operation, his symptom had improved. However, a few days later, his confirmed pathologic report was presented as MPNST (). The contrast-enhanced MRI was followed at 1 month after the operation and revealed a total removal of tumor (). We recommended the postoperative radiotherapy for prevention of local recurrence. However, the patient declined the external beam radiation due to the fear of potential radiation risk. Six months after surgery, the patient revisited our clinic with a moderate headache. Contrast-enhanced MRI was obtained including brain and spine for workup. Spine and brain MRI showed that the tumor recurrence with leptomeningeal, multiple spinal cord and brain metastases (). Complete surgical clearance of the tumor was not technically feasible, owing to the multiple metastases. Therefore, the patient was referred for adjuvant chemotherapy. In addition, intrathecal chemotherapy was performed. However, no significant effect was observed and the patient's condition deteriorated gradually. After 4 months of chemotherapy, he was referred to the hospice hospital and died within a month.