title: Intradural extramedullary spinal ependymoma: a benign pathology?
abstract: METHODS
  Spinal ependymoma is a benign central nervous system tumor described as an intramedullary lesion more frequently located at the conus medullaris. It has been described exceptionally in the literature as an intradural extramedullary tumor.
  
  
  OBJECTIVE
  Presentation of an extremelly rare location and evolution of extremedullary ependymoma and discussion of its probable origin, differential diagnosis, treatment options, and follow-up.
  
  
  BACKGROUND
  This case demonstrates an unusual location of a benign ependymal tumor in the extramedullary space with a total resection, which recurred in a lower level with a malignant transformation with the same extramedullary location.
  
  
  METHODS
  The authors present the case of a 47-year-old woman with a subacute spinal cord dysfunction and an intradural extramedullary D2-D3 tumor mimicking meningioma or neurinoma. At surgery, an encapsulated intradural extramedullary mass was found, but neither dural attachment nor medullary infiltration was present.
  
  
  RESULTS
  After complete resection, anatomic-pathologic studies confirmed that the lesion was a benign classic ependymoma. Good neurologic outcome was achieved, and no residual tumor was present at magnetic resonance imaging (MRI) control performed at 3 and 9 months later. One year after surgery, a new intradural extramedullary tumor was found at the D4 level without recurrence at D2. The patient was operated on again, but at this time the histologic study showed an anaplastic ependymoma with a proliferation index of 25% measured by Ki-67. Whole central nervous system radiotherapy was performed.
  
  
  CONCLUSIONS
  All of the previously reported cases of spinal intradural extramedullary ependymomas carried out a benign course. The case we are reporting is the first one in which malignant transformation occurred. This tumor should be taken into account in the differential diagnosis of intradural extramedullary lesions. Moreover, close follow-up is recommended for this unusual location of ependymomas.
authors.affiliation: Department of Neurosurgery, Hospital Clinico San Carlos, Madrid, Spain. santigilrob@yahoo.es
authors.forename: Santiago Gil
authors.initials: SG
authors.lastname: Robles
authors.forename: Cristobal
authors.initials: C
authors.lastname: Saldaña
authors.forename: Gregorio R
authors.initials: GR
authors.lastname: Boto
authors.forename: Armando
authors.initials: A
authors.lastname: Martinez
authors.forename: Alvaro Perez
authors.initials: AP
authors.lastname: Zamarron
authors.forename: Manuela
authors.initials: M
authors.lastname: Jorquera
authors.forename: Pedro
authors.initials: P
authors.lastname: Mata
mesh_terms: D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D004388:Dura Mater / Q000473:pathology*; D004806:Ependymoma / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008579:Meningioma / Q000175:diagnosis; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D009442:Neurilemmoma / Q000175:diagnosis; D013125:Spinal Neoplasms / Q000473:pathology* / Q000601:surgery