title: Intravascular papillary endothelial hyperplasia arising within a posteroinferior cerebellar artery aneurysm: case report and review of the literature.
abstract: OBJECTIVE
  Intravascular papillary endothelial hyperplasia (IPEH) is an atypical proliferation of endothelium that results in abnormal organization for thrombus formation. Intracranial IPEH is a rare entity and has not been reported to arise from within an intracranial aneurysm. Furthermore, the elapsed time during which acquired intracranial IPEH develops has not been previously documented.
  
  
  METHODS
  In this case report, a patient with facial and neck pain was noted to have an enhancing mass lesion lateral to the medulla in magnetic resonance imaging scans. Angiography revealed a vascular mass adjacent to the posteroinferior cerebellar artery. Normal magnetic resonance imaging and magnetic resonance angiographic findings had been obtained for the patient 29 months earlier.
  
  
  METHODS
  During surgery, a thrombosed, 2.5-cm, posteroinferior cerebellar artery aneurysm was resected and noted to contain florid IPEH. There has been no evidence of recurrence in 1 year of follow-up monitoring. A literature search revealed 13 cases of intracranial IPEH, in which recurrence was observed for incompletely resected lesions.
  
  
  CONCLUSIONS
  IPEH can develop in a relatively short time, can present as a hypervascular mass lesion or within an intracranial aneurysm, and should be completely resected to prevent recurrence.
authors.affiliation: Department of Radiology, Harper Hospital/Detroit Medical Center and Wayne State University, Michigan, USA. walter-lesley@uiowa.edu
authors.forename: W S
authors.initials: WS
authors.lastname: Lesley
authors.forename: W J
authors.initials: WJ
authors.lastname: Kupsky
authors.forename: M
authors.initials: M
authors.lastname: Guthikonda
mesh_terms: D015901:Angiography, Digital Subtraction; D002531:Cerebellum / Q000098:blood supply*; D002533:Cerebral Angiography; D004730:Endothelium, Vascular / Q000473:pathology*; D005260:Female; D006801:Humans; D006965:Hyperplasia; D002532:Intracranial Aneurysm / Q000175:diagnosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged