IDH1 and neoplasm: Due to inconsistent tumor specimen availability and adequacy, it was not possible to perform all molecular tests on all paired tumor samples; therefore, in cases with sparse tissue, focused panels of genomic alterations were selected based on relevance to tumor histopathologic classification (e.g., prioritizing IDH1 mutation testing for diffuse astrocytomas) and location (i.e., H3K27M IHC testing for tumors of midline location).