Intramedullary primitive neuroectodermal tumor presenting with rapidly-progressive cauda equina syndrome.

A 39-year-old male presented with gait disturbances with rapid deterioration for 2 weeks. Neurological examination found paraparesis, sensory loss in the L1-S5 dermatomes, and vesicorectal dysfunction. Magnetic resonance (MR) imaging revealed a fusiform intramedullary tumor at T12-L1 levels with heterogeneous enhancement. The patient underwent microsurgical tumor resection. A myelotomy exposed a highly vascular tumor that was subtotally resected. Histological examination demonstrated hypercellular tumor accompanied by significant cell atypism and mitotic figures. Immunohistochemical staining was positive for glial fibrillary acidic protein, S-100 protein, synaptophysin, and INI-1, consistent with primitive neuroectodermal tumor (PNET). Postoperatively, the patient underwent irradiation to the whole craniospinal axis. He experienced local recurrence 7 months after surgery. MR imaging performed at 10 months revealed holocord progression and intracranial dissemination. The patient died 13 months after the onset of the disease. PNET should be considered in the differential diagnosis of an intramedullary spinal cord tumor.