title: Subpial hemangiopericytoma with marked extramedullary growth: case report.
abstract: OBJECTIVE
  Hemangiopericytomas, vascular tumors arising in soft tissue, are relatively rare in the central nervous system; they comprise less than 1% of all hemangiopericytomas. Central nervous system hemangiopericytomas occur primarily in the epidural space of the brain and spinal cord. There are no previous reports of subpial, extramedullary growing central nervous system hemangiopericytomas.
  
  
  METHODS
  We document the first case of a subpial hemangiopericytoma with extramedullary growth in the thoracic spine. The patient was a 31-year-old man who developed progressively worsening left lower limb numbness that was followed by gait disturbance over the course of 4 months.
  
  
  METHODS
  Magnetic resonance imaging revealed an intradural tumor at the T4-T6 level of the thoracic spine. Because the patient's symptoms progressed, he underwent resection of the tumor, which had arisen in the spinal cord subpially without attachment to the dura mater.
  
  
  CONCLUSIONS
  The pathological diagnosis was hemangiopericytoma. Differential diagnoses include hemangioblastoma, meningioma, schwannoma, and solitary fibrous tumor, the clinical course and prognosis of which are different from hemangiopericytoma. Our experience indicates that hemangiopericytomas can occur as intradural tumors arising from the subpial portion.
authors.affiliation: Department of Neurosurgery, Hokkaido University, Graduate School of Medicine, Sapporo, Japan. gktqx702@ybb.ne.jp
authors.forename: Daina
authors.initials: D
authors.lastname: Kashiwazaki
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Hida
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yano
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Seki
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Iwasaki
mesh_terms: D000328:Adult; D018450:Disease Progression; D004388:Dura Mater / Q000473:pathology* / Q000601:surgery; D006393:Hemangiopericytoma / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D013120:Spinal Cord Neoplasms / Q000473:pathology* / Q000601:surgery