Anaplastic oligodendroglioma

see Anaplastic oligodendroglioma, IDH-mutant & 1p/19q-codeleted.

After substantial redefinition in the 2016 edition, the diagnosis of oligodendroglioma, IDH-mutant and 1p/19q-codeleted, is not markedly changed in the 2021 fifth edition. As the name states, IDH mutation and 1p/19q codeletion are required for the diagnosis of oligodendrogliomas. Historical pathologic features such as “perinuclear halos” creating “fried egg cells” and “chicken wire vasculature” remain characteristic although not necessary or sufficient for diagnosis. These tumors may be assigned CNS WHO grades of 2 or 3, and in the latter case the previous term “anaplastic oligodendroglioma” is no longer formally applied.