A rare case of metastatic renal cell carcinoma resembling a nerve sheath tumor of the cauda equina.

We present a rare case of solitary metastasis to the cauda equina from the kidney. The patient was a 68-year-old man with a two-year history of low back pain. His past medical history revealed a renal cell carcinoma diagnosed seven years earlier. His lumbosacral MR imaging showed a well-demarcated, intradural extramedullary mass at the L3 level. He underwent an L2-4 laminectomy. The operative findings of the tumor quite resembled that of a nerve sheath tumor. It did not infiltrate into the subarachnoid space and involved only one spinal nerve. Pathology of the tumor was a metastasis of the renal cell carcinoma. Only 10 cases with such a metastasis to the cauda equina have been reported in the English literature. We added the 11th and reviewed the literature with reference to tumor pathologies, clinical findings and route of metastasis to the cauda equina.