title: Unusual metastasis to the cauda equina from renal cell carcinoma.
abstract: METHODS
  This is a case report of a patient with renal cell carcinoma and intradural metastasis to the cauda equina.
  
  
  OBJECTIVE
  To present a rare case of an intradural metastasis from renal cell carcinoma and to discuss the clinical features of metastatic tumors in the cauda equina and the possible mechanism of the tumor spread to the cauda equina.
  
  
  BACKGROUND
  Intradural spinal metastasis has been rarely reported in the English literature. Only two reports that describe the spread of metastatic renal cell carcinoma to the cauda equina have been published.
  
  
  METHODS
  A 61-year-old man who underwent a nephrectomy for the treatment of renal cell carcinoma presented with worsening low back pain that radiated to both legs. Magnetic resonance imaging showed an ill-defined tumor mass in the cauda equina at L3. After a recapping T-saw laminoplasty of L3 was performed, the tumor was excised and the nerves involved in the tumor were transected.
  
  
  RESULTS
  Pathologic examination showed papillary renal cell carcinoma with identical histology to the primary tumor. The patient's low back pain and radiating leg pain were relieved after operating.
  
  
  CONCLUSIONS
  The majority of cauda equina tumors are primary tumors, and metastases are very rare. Intradural spinal metastasis pain is a characteristic cramping pain provoked by light percussion on the lumbar spine, becoming severe when sleeping in the flexion or sitting position. Magnetic resonance imaging is a useful tool for detecting intraspinal metastasis when the patient is complaining of a unique pain. A recapping T-saw laminoplasty to preserve posterior elements with tumor removal is feasible for relieving pain and demonstrating the pathology.
authors.affiliation: Department of Orthopedic Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Takada
authors.forename: Minoru
authors.initials: M
authors.lastname: Doita
authors.forename: Kotaro
authors.initials: K
authors.lastname: Nishida
authors.forename: Juichi
authors.initials: J
authors.lastname: Miura
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshiya
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000556:secondary / Q000601:surgery; D002420:Cauda Equina / Q000473:pathology* / Q000601:surgery; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy; D013125:Spinal Neoplasms / Q000175:diagnosis* / Q000556:secondary / Q000601:surgery