Abstract
We report an uncommon case of primitive neuroectodermal tumor/ Ewing's sarcoma of the lumbar and sacral nerve plexus in a 17years old boy who presented with an intense pain in the lower back radiating to legs. Magnetic resonance imaging showed a soft tissue mass with thickening of lumbar and sacral spinal nerve roots (L5-S3 level), along with widening of the corresponding foramina. There was also posterior scalloping of L5/S1 vertebrae and invasion of the sacral bone. A Partial resection has been performed, and the ensuing histopathology confirmed the diagnosis of PNET/Ewing's sarcoma. MRI in conjunction with histopathology are the key to narrow down the differential diagnoses list. PNET of lumbosacral area remain scarce, and only few cases have been reported nowadays. Given to the aggressivity of these tumors, the prognosis is poor despite appropriate treatment.