title: Intradural extramedullary hemangiopericytoma of the thoracic spine infiltrating a nerve root: a case report and literature review.
abstract: METHODS
  Review the presentation and diagnosis of an intradural extramedullary hemangiopericytoma of the thoracic spine.
  
  
  OBJECTIVE
  To present a rare case of intradural, subpial hemangiopericytoma in the thoracic spine, with a brief overview of the literature.
  
  
  BACKGROUND
  Spinal intradural extramedullary hemangiopericytoma is rare entity that radiographically mimics nerve-sheath tumors. These lesions are typically diagnosed at surgery performed due to suspicion of tumor.
  
  
  METHODS
  A 20-year-old man who presented with back pain, leg weakness, and sphincter incontinence. MR imaging demonstrated an intradural extramedullary lesion at the T9-T10 level that was isointense on T1- and T2-weighted images and homogeneously enhancing after administration of gadolinium, with cystic components seen on T2-weighted images. The preoperative diagnosis was meningioma or schwannoma.
  
  
  RESULTS
  At surgery, the lesion was bluish and completely subpial, with apparent nerve root invasion. Pathological examination revealed a neoplasm adjacent to a nerve root with possible focal infiltration. Abundant reticulin fibers and widened, branching vascular channels imparting a staghorn appearance were seen. Up to five mitotic figures were counted in one high-power field. On immunostaining, the neoplastic cells were diffusely immunoreactive for CD99 and immunonegative for EMA, CD34, and S-100 protein. The pathological diagnosis was consistent with anaplastic hemangiopericytoma, WHO grade III.
  
  
  CONCLUSIONS
  This is the ninth report of spinal intradural hemangiopericytoma. The location of the neoplasm supports the hypothesis that hemangiopericytoma may arise from the spinal pial capillaries.
authors.affiliation: Department of Neurosurgery, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: Samuel
authors.initials: S
authors.lastname: Moscovici
authors.forename: Fernando
authors.initials: F
authors.lastname: Ramirez-DeNoriega
authors.forename: Yakov
authors.initials: Y
authors.lastname: Fellig
authors.forename: Guy
authors.initials: G
authors.lastname: Rosenthal
authors.forename: José E
authors.initials: JE
authors.lastname: Cohen
authors.forename: Eyal
authors.initials: E
authors.lastname: Itshayek
mesh_terms: D000071443:12E7 Antigen; D015703:Antigens, CD / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D003937:Diagnosis, Differential; D004388:Dura Mater / Q000473:pathology* / Q000601:surgery; D006393:Hemangiopericytoma / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D013125:Spinal Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D013126:Spinal Nerve Roots / Q000473:pathology* / Q000601:surgery; D013904:Thoracic Vertebrae / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules