title: Malignant potential of skull base versus non-skull base meningiomas: clinical series of 1,663 cases.
abstract: BACKGROUND
  About 90 % of meningiomas are benign (WHO grade I), atypical and anaplastic variants exist (WHO grade II/III, 10 %). Tumour grade has important implications for management. Non-invasive diagnosis of tumour grade is still not feasible. The purpose of this survey was to analyse epidemiological risk factors such as sex, age and location for a higher grade (WHO grade II/III) meningioma in a large surgical series.
  
  
  METHODS
  A retrospective study comprising 1,663 patients operated on for an intracranial meningioma in a single tertiary-care centre. The population was analysed for correlations including WHO grade, histological subtype, tumour localisation, patient age and gender. Additionally correlations between Ki67 index/WHO grade and localisation were analysed.
  
  
  RESULTS
  A binary logistic regression analysis revealed non-skull base localisation (OR 1.779 [CI 1.069-2.960, p = 0.0027]) and age ≥65 years (OR 1.549 [CI 1.214-2.624, p = 0.012]) as significant risk factors for a higher WHO grade. Male gender showed a trend for a higher risk in χ(2) analysis. An analysis of the Ki67 index revealed an increased index for non-skull base localisation compared with skull base (p < 0.001). Correlation analysis of Ki67 distribution in WHO grade I meningiomas revealed higher Ki67 indices for non skull base localisation (p = 0.0024).
  
  
  CONCLUSIONS
  Non-skull base localisation and age ≥65 years are independent risk factors for higher grade meningiomas. In other terms, the malignant potential of skull base meningiomas is low. This information is important when advising a patient about individual treatment options (observation, surgery or radio-surgery) and prognosis.
authors: Neurochirurgische Klinik, Universitätsklinikum Düsseldorf, Heinrich-Heine-Universität, Moorenstrasse 5, 40229, Düsseldorf, Germany.
authors: Jan Frederick
authors: JF
authors: Cornelius
authors: Philipp Jörg
authors: PJ
authors: Slotty
authors: Hans Jakob
authors: HJ
authors: Steiger
authors: Daniel
authors: D
authors: Hänggi
authors: Marc
authors: M
authors: Polivka
authors: Bernard
authors: B
authors: George
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted; D019394:Ki-67 Antigen / Q000032:analysis; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D060787:Neoplasm Grading; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D019292:Skull Base Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*
chemical_list: D019394:Ki-67 Antigen