title: Intraorbital meningiomas: a pathologic review using current World Health Organization criteria.
abstract: BACKGROUND
  Meningiomas represent approximately 4% of all intraorbital tumors and can arise from the optic nerve or extend into the orbit from adjacent structures.
  
  
  OBJECTIVE
  To examine a cohort of intraorbital meningiomas and use the current World Health Organization (WHO) scheme to assess the effect of changes to the classification of tumors at this site.
  
  
  METHODS
  The histopathology and clinical findings of intraorbital meningiomas resected between 1968 and 2008 at our institution were reviewed according to the WHO 2007 classification scheme.
  
  
  RESULTS
  A total of 51 intraorbital meningiomas were reviewed. The mean age at presentation was 45 years, but 5 tumors arose in children. Two patients were known to have neurofibromatosis type 2, and 1 had inherited retinoblastoma. Orbital meningiomas were more frequently encountered in women (30 cases) than in men (21 cases). In 21 patients, the tumor was associated with the optic nerve. The most common (25 of 51 tumors; 49%) histopathologic subtype was meningothelial. Most (47 of 51; 92%) of the tumors were WHO grade I. Four tumors (8%) were WHO grade II, with 4 or more mitotic figures per 10 high-power fields, brain invasion, chordoid histology, or a combination of these features.
  
  
  CONCLUSIONS
  Intraorbital meningiomas were most frequently of the meningothelial or transitional subtypes and were WHO grade I. One relatively common intracranial subtype, fibrous meningioma, was not encountered. The percentage of WHO grade II tumors in the orbit (8%) is similar to that reported for intracranial tumors using the current grading scheme.
authors.affiliation: Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Deepali
authors.initials: D
authors.lastname: Jain
authors.forename: Katayoon B
authors.initials: KB
authors.lastname: Ebrahimi
authors.forename: Neil R
authors.initials: NR
authors.lastname: Miller
authors.forename: Charles G
authors.initials: CG
authors.lastname: Eberhart
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000145:classification / Q000473:pathology*; D008579:Meningioma / Q000145:classification / Q000473:pathology*; D008875:Middle Aged; D012189:Retrospective Studies; D014944:World Health Organization