Cauda equina malignant peripheral nerve sheath tumor presenting with subarachnoid hemorrhage: a case report.

Malignant peripheral nerve sheath tumors (MPNST) are uncommon aggressive neoplasms, frequently associated with type I neurofibromatosis. This is the first case of intradural lumbar spine MPNST with intraoperative findings of associated subarachnoid hemorrhage (SAH). A 72-year-old man presented to the emergency department with severe acute low back pain. Neurological examination was unremarkable. Gadolinium-enhanced MRI of the lumbar spine showed an irregularly shaped intradural lesion extending from L3 to L5. The lesion exhibited a medium signal both on T1 and T2-weighted imaging with peripheral enhancement. Through an L3-L5 laminectomy, a diffuse SAH, and a tumor tightly adherent to cauda equina nerve roots were found. Specimen examination revealed a fusocelular tumor with pleomorphic and hyperchromatic nuclei, positive for S100, and SOX10. On an 8-month follow-up, he had no neurological deficit, with a Karnofsky performance score of 90 points. Surgical evidence of SAH in lumbar spine intradural MPNST is a novel finding.