What Every Neuropathologist Needs to Know: Update on cIMPACT-NOW.

World Health Organization (WHO) central nervous system tumor classification represents the primary source of updates on diagnostic classes, grades, and criteria. However, recent and ongoing advances in molecular pathogenesis warrant more rapid integration into clinical practice between WHO updates. To accomplish this, the consortium to inform molecular and practical approaches to CNS tumor taxonomy-not official WHO (cIMPACT-NOW) was established in 2016. Since then, cIMPACT-NOW has convened 3 separate working committees to address classification and grading questions and challenges. This review covers the progress that these working committees have made on their specific topics.