Until 2016, oligoastrocytomas were considered a distinct tumor entity with mixed oligodendroglial and astrocytic histological features, and between 2016 and 2021, they could only be diagnosed in cases with unknown 1p/19q and IDH status (these cases were designated as “oligoastrocytoma, NOS (Not Otherwise Specified)” and diagnosis was not recommended unless molecular testing was unavailable)6,7. This evidence concerns the gene IDH1 and oligoastrocytoma.