Cimpact-now updates and the 2021 who classification of central nervous system tumors: Where does it leave underdeveloped neuropathology centers and how to report diffuse gliomas

Abstract

The classification of central nervous system tumors, first introduced by Bailey and Cushing in 1926, has been constantly updated by the World Health Organization. The latest fifth edition, introduced in 2021, although the bluebook was officially published in the first weeks of 2022, is the first classification to officially introduce histological and molecular grading criteria for the differ-ent nosological units based on mutation-oriented, evidence-based patient prognosis. So far, these changes have had no impact on patient treatment, despite the stratified patient risk and prognosis. As such, there has been little initiative for underfunded and underdeveloped neuropathological centers to introduce molecular diagnostic modalities, especially as they are of little use to other tumor groups. This has disadvantaged neuropathologists in such centers, especially when reporting the most common of these tumor groups – diffuse (high-grade) gliomas, as mutational status is key in these nosological units. Herein we review the changes in the classification system and suggest an integrated descriptive manner of reporting such tumors, allowing for the oncologist to initiate treatment, suggesting the necessary mutations to be evaluated and not misleading the patient that he was misdiagnosed upon consultation at a referral center.