Report of clinical features, diagnostic and surgical aspects observed in a case of adult peripheral neuroblastoma infiltrative of the lumbosacral plexuses. The patient, a 39-year-old male, presented with sciatalgia and progressive crural monoplegia. Characteristic histological features of this rare tumor are described. Surgical resection was attempted via a posterior transgluteal approach to the retroperitoneum through the greater sciatic foramen.