Astrocytomas, Other Gliomas, and Glioneuronal/Neuronal Tumors

This category includes, among other diagnoses, pediatric-type diffuse low-grade gliomas, pediatric-type diffuse high-grade gliomas, circumscribed astrocytic gliomas, glioneuronal tumors, and neuronal tumors.

For pediatric-type diffuse gliomas, rearrangements in the MYB family of transcription factors (MYB and MYBL1) are the most commonly reported genomic alteration in low-grade tumors.[2-4] Other alterations observed include FGFR1 alterations (primarily duplications involving the tyrosine kinase domain),[3,4] BRAF alterations, NF1 variants, and RAS family variants.[2,3] IDH1 variants, which are the most common genomic alteration in adult-type diffuse astrocytomas, are uncommon in children with diffuse astrocytomas and, when present, are observed almost exclusively in older adolescents.[2,5]

The diffuse midline glioma, H3 K27M-altered, category includes tumors previously classified as diffuse intrinsic pontine glioma (DIPG). Most of the data is derived from experience with DIPG. This category also includes gliomas with the H3 K27M variant arising in midline structures such as the thalamus.