title: Hemangiopericytoma of the cerebellopontine angle: a case report and review of the literature.
abstract: BACKGROUND
  Intracranial hemangiopericytoma represents a rare intracranial tumor that is typically difficult to distinguish from meningioma based on clinical presentation and radiographic findings. These inherently aggressive neoplasms have been observed to occur in numerous intracranial compartments; however, isolated involvement of the CPA is essentially unreported. The authors present a case of a young lady with presumed right acoustic schwannoma, which proved to be HPC on histopathology. The case is described; and a review of the literature pertaining to the diagnosis, optimal management, and follow-up for these lesions is provided.
  
  
  METHODS
  A 37-year-old Asian woman presented with a 7-month history of right ear and mandible numbness, as well as subjective hearing loss involving the right ear. Magnetic resonance imaging demonstrated the presence of a homogeneously enhancing extraaxial lesion in the right CPA, radiographically suggestive of an acoustic schwannoma. The lesion proved to be an intracranial HPC on histologic sections. Review of the neurosurgical literature yielded only one prior detailed account of HPC confined to the CPA. The patient underwent right retrosigmoid craniotomy for gross total resection of the mass, followed by stereotactic radiotherapy several weeks postoperatively.
  
  
  CONCLUSIONS
  Given the fundamentally different treatment approach for HPCs over other more common CPA tumors, it is imperative that the treating surgeon consider this rare diagnosis when evaluating patients with lesions localized to this area. Specifically, gross total resection, followed by adjuvant SRT, provides patients with the highest probability for disease-free survival, based on current evidence in the neurosurgical literature.
authors.affiliation: Division of Neurosurgery, David Geffen School of Medicine at UCLA, NPI, Box 957039, Los Angeles, CA 90095-7039, USA. vtashjian@mednet.ucla.edu
authors.forename: Vartan S
authors.initials: VS
authors.lastname: Tashjian
authors.forename: Negar
authors.initials: N
authors.lastname: Khanlou
authors.forename: Harry V
authors.initials: HV
authors.lastname: Vinters
authors.forename: Rinaldo F
authors.initials: RF
authors.lastname: Canalis
authors.forename: Donald P
authors.initials: DP
authors.lastname: Becker
mesh_terms: D000328:Adult; D002528:Cerebellar Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy / Q000601:surgery / Q000628:therapy*; D002530:Cerebellopontine Angle / Q000473:pathology / Q000601:surgery; D003937:Diagnosis, Differential; D005260:Female; D006393:Hemangiopericytoma / Q000175:diagnosis* / Q000532:radiotherapy / Q000601:surgery / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008579:Meningioma / Q000175:diagnosis / Q000601:surgery; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control; D049268:Positron-Emission Tomography; D018714:Radiotherapy, Adjuvant