Metastatic renal cell carcinoma, with a radiographically occult primary tumor, presenting in the operative site of a thoracic meningioma: long-term follow-up: Case report.

Lesions metastatic to the site of a meningioma resection from a different primary tumor are rare. Metastasis of a tumor without a known primary tumor is also rare. Metastasis of a renal cell carcinoma, without an identifiable primary tumor, to the bed of a meningioma resection has not been previously reported. The authors describe the case of a 54-year-old man who presented with decreased sensory and motor function in the lower extremities. He underwent T3-5 laminectomies and gross-total removal of an intradural, extramedullary meningioma. The postoperative course was uneventful, and the patient regained full neurological function. After a 3-year period, he developed progressive upper thoracic pain and lower-extremity paresthesias. Imaging studies showed an epidural mass at the T2-4 levels and what appeared to be blastic involvement of the T2-4 vertebrae. A metastatic workup was negative. Emergency revision laminectomies yielded a fibrous, nonvascular mass. Neuropathology was consistent with metastatic renal cell carcinoma. After 6 months, the patient's symptoms of pain and paresthesias recurred. Repeat excision, with decompression of the spinal cord, revealed tumor cells morphologically and immunophenotypically similar to those obtained from the prior surgery. Cytogenetic analysis confirmed the presence of metastatic renal cell carcinoma. A novel case of an epidural metastatic renal cell carcinoma, of unknown primary origin, in the same operative bed of a previously resected intradural, extramedullary meningioma of the thoracic spine is reported.