Primary Extradural Peripheral Primitive Neuroectodermal Tumor (Extraskeltal Ewing’s Sarcoma) Arising from the Sacral Spinal Nerve Root: A Case Report and Review of the Literature

Primitive neuroectodermal tumors (PNET) are rare, and are even rarer when they arise from the spinal cord tissue. Therefore, we report a case of peripheral PNET that arose from the sacral spinal nerve root. The patient was a 30-year-old woman who presented with left lower extremity pain, and MRI revealed a neoplastic lesion in the left S1 nerve root canal of the sacral region. Subsequent imaging and testing were not able to confirm a diagnosis, although we suspected a benign tumor as a candidate for the differential diagnosis. We performed surgery to remove the tumor, and confirmed total resection. Our subsequent pathological testing confirmed a diagnosis of peripheral PNET, and we elected to treat the patient using concurrent radiotherapy and the standard chemotherapy for Ewing’s sarcoma. The treatment was successful, and the patient was free from recurrence at the 27-month follow-up. Although it may be impossible to achieve a preoperative imaging diagnosis in similar cases, we believe that imaging remains an important part of the differential diagnosis to facilitate successful treatment.