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OBJECTIVE: This study was undertaken to assess a possible relationship between the tumor location and the incidence of World Health Organization (WHO) Grades II and III meningiomas.

METHODS: A retrospective review of 794 consecutive patients who underwent meningioma resection between January 1991 and March 2004 was conducted. Among these, 47 patients (5.9%) with WHO Grade II meningiomas and 16 patients (2%) with Grade III meningiomas were further analyzed. Tumor location was assessed using preoperative magnetic resonance imaging scans and/or operative reports. Histological grading was done according to the WHO 2000 Classification scheme.

RESULTS: WHO Grade II tumors were found in eight out of 289 (2.8%) cranial base meningiomas and in zero spinal meningiomas, compared with 39 out of 429 (9.1%) non-cranial base meningiomas. Grade III histology was encountered in two …