Should Criteria for Atypical Meningioma Be Changed

Sarah E. Martin, Stephanie A. Wagner, Eyas M. Hattab

Abstract


Current WHO classification of atypical meningiomas can be subjective, and there are multiple criteria by which a meningioma may qualify for grade II designation. A meningioma is labeled atypical or WHO grade II if any one of the following five criteria are met: four or more mitotic figures per ten high-power fields; brain invasion; clear cell morphology; chordoid phenotype; or three or more “soft” criteria (necrosis, hypercellularity, small cell change, prominent nucleoli, and sheeting architecture). Whether a meningioma has one or more of these criteria, the tumor is still given the same grade II designation and therefore, the same implied prognosis. We hypothesize that meningiomas with greater numbers of grade II qualifying criteria may behave worse than those with only one.
Our institution’s archives were searched for atypical meningiomas from 1986 to 2007. Fifty meningiomas that qualify as atypical by today’s standards were obtained. Each case was evaluated for the above histologic criteria. The number of qualifying criteria present in each case was then tallied, and the meningiomas were placed into one of four groups (having 1, 2, 3, or 4 different grade II criteria). The time to recurrence was then compared between the four groups.
Preliminary statistical analysis suggests a trend that meningiomas with three or four criteria tend to have a shorter time to recurrence than do those with only one or two criteria. In addition, meningiomas with four different atypical criteria recurred more often than those tumors with one, two or three criteria. Additional data collection and statistical analysis is underway.
Additional data collection and statistical analysis is underway.

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