In contrast with the previous diagnostic criteria, which relied only on histopathological evidence (4), the integrated diagnosis of oligodendroglioma based on the World Health Organization Classification of Tumors of the Central Nervous System (WHO CNS 5) criteria requires the codeletion of chromosome arms 1p and 19q and isocitrate dehydrogenase gene (IDH) mutation (mut) (5). This evidence concerns the gene IDH1 and oligodendroglioma.