Background: Grade II and III meningiomas have higher rates of tumor recurrence than grade I meningiomas after surgery and/or external irradiation. As the utility of noninvasive treatments for brain tumors increases, it is becoming increasingly important to assess the likelihood that a tumor is not benign before treatment initiation. Hence, the authors have reviewed a large series of their patients to determine risk factors for higher-grade pathology, with particular interest paid to tumor location.

Methods: The authors reviewed 378 patients presenting at their institution from 2000 to 2007 with histologically confirmed meningioma, central pathology grading according to the World Health Organization 2000 guidelines, and tumor location confirmed with preoperative imaging. They performed univariate and multivariate logistic regression on potential risk factors for high-grade pathology.

Results: Risk factors for grade II/III pathology included nonskull base location (2-fold) and male sex (2-fold). Patients with prior surgery had a 3-fold increased incidence of higher-grade meningiomas at presentation at the authors' center. The authors controlled for this referral bias by performing a multivariate regression, and analysis without patients receiving prior treatment. Ninety-seven percent of operations were performed for tumor size and clinical symptoms, whereas <3% were performed for interval growth or features concerning higher-grade pathology.

Conclusions: Nonskull-base meningiomas, male sex, and prior surgery impart increased risk for grade II or III pathology. This increased risk translates to probable poorer prognosis and increased likelihood of recurrence after treatment. Thus, it is prudent to take these specific variables into consideration in conjunction with the complete clinical presentation when advising patients regarding their prognosis.