Among the strengths of our study, we highlight the relatively large number of patients with histone-mutant tumors, the availability of detailed genomic information from both tumor and CSF confirming H3 mutation in all cases, TP53 in a subset of cases, and co-existence of PDGFRA, FGFR1, and BRAF in some patients, underscoring the importance of comprehensive NGS as opposed to isolated H3 testing. The gene discussed is PDGFRA; the disease is neoplasm.