Atypical and anaplastic meningiomas: prognostic implication of clinicopathological features

¹ DongGuk University International Hospital, Korea, Republic of
² Department of Neurosurgery, Seoul National University College of Medicine, Korea, Republic of
³ Department of Pathology, Seoul National University College of Medicine, Korea, Republic of

^* To whom correspondence should be addressed. E-mail: yschung{at}snu.ac.kr.

Accepted 18 August 2007

	Abstract

Objectives: To evaluate patient outcome and investigate the prognostic factors of high-grade meningiomas by adopting the 2000 World Health Organization (WHO) classification system.

Methods: Between 1986 and 2004, 74 patients were diagnosed with high-grade meningioma: 33 with atypical and 41 with anaplastic meningioma. The mean follow-up was 58.5 months. We reclassified all surgical specimens, according to the 2000 WHO classification system, using two expert neuropathologists.

Results: Forty of 74 meningiomas were reclassified as atypical meningioma and 24 as anaplastic meningioma. Overall and recurrence-free survivals were significantly longer in patients with atypical than in those with anaplastic meningioma: 142.5 versus 39.8 months and 138.5 versus 32.2 months, respectively (P < 0.001). In patients with atypical meningiomas, brain invasion and adjuvant radiotherapy were not associated with survival; however, in the brain invasion subgroup, adjuvant radiotherapy improved patients¡ survival. In patients with anaplastic meningioma, the prognostic factors were brain invasion, adjuvant radiotherapy, malignant progression, p53 overexpression, and extent of resection. The p53 overexpression was the only factor associated with malignant progression (P = 0.009).

Conclusions: The 2000 WHO classification surely has identified the truly aggressive meningiomas better than did the previous criteria. Precise meningioma grading system may help to avoid overtreatment of patients with an atypical meningioma and, once the tumor has "declared itself" by recurrence and upgrading histological features, it goes on to be a tumor poorly amenable to current therapies.

Keywords: anaplastic meningioma, atypical meningioma, histopathology, malignant progression, prognosis