RESUMEN
A 67-year-old male patient underwent a left nephrectomy for a renal cell carcinoma. Thirty-eight months later, he presented with right sided lower backache, radiating to the posterior aspect of his thigh, calf and foot, paraesthesiae and numbness in the distribution of the right S1 and S2 dermatomes. The presumptive diagnosis was of nerve root entrapment secondary to a disc prolapse. MRI scan of the lumbosacral spine revealed an enlarged S1 root canal containing a solid solitary lesion suggestive of a neurofibroma of the S1 nerve root. Because of persistent pain, he underwent a right L5/S1 hemilaminectomy. A lesion originating from the right S2 nerve root was found and excised. The patient made an uneventful postoperative recovery with complete resolution of his right leg pain. The histopathological examination revealed a portion of the nerve root and dorsal root ganglion infiltrated by metastatic renal cell carcinoma. Although uncommon, nerve root infiltration by a metastasis should be included in the differential diagnosis of back pain and sciatica, especially if there is a previous history of malignant disease