title: The potential risk factors for atypical and anaplastic meningiomas: clinical series of 1,239 cases.
abstract: BACKGROUND
  Determining factors that could accurately predict pathological features of meningiomas before histological diagnosis would help surgeons to proper balance the risk of operation and the resection grade. The aim of this study was to explore the potential risk factors for atypical (WHO Grade II) and anaplastic (WHO Grade III) meningiomas.
  
  
  METHODS
  Records of 1,239 patients between January 2009 and January 2013 were included in this research. Furthermore, immunohistochemistry with Ki67 was analysed in 368 samples.
  
  
  RESULTS
  The Pearson's chi-square test showed an increased risk for male gender for atypical and anaplastic meningiomas (P < 0.001) and an increased risk for cerebral convexity for atypical and anaplastic meningiomas (P < 0.001). However, significant differences in the terms of falx/sagittal sinus and intraventricular were not found. Patients with a Ki67 index ≥ 5% were significantly more likely to have atypical and anaplastic meningiomas than those patients with a Ki67 index < 5% (P < 0.001). In addition, the percentage of patients with a Ki67 index ≥ 5% in cerebral convexity meningiomas was higher than in non-cerebral convexity location (P = 0.006).
  
  
  CONCLUSIONS
  The results indicate that male gender, cerebral convexity are significant risk factors for atypical and anaplastic meningiomas.
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Ruo-Fei
authors: RF
authors: Liang
authors: Department of Pathology, West China Hospital of Sichuan university Chengdu, P. R. China.
authors: Ying-Jie
authors: YJ
authors: Xiu
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Xiang
authors: X
authors: Wang
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Mao
authors: M
authors: Li
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Yuan
authors: Y
authors: Yang
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Qing
authors: Q
authors: Mao
authors: Department of Neurosurgery, West China Hospital of Sichuan University Chengdu, P. R. China.
authors: Yan-Hui
authors: YH
authors: Liu
keywords: Cerebral convexity; meningiomas; risk factor