Oligodendroglioma (grade 3)
The patient went on to have debulking.
Sections show a moderately cellular glial tumor composed of sheets of tumor cells with a "chicken-wire" capillary network and scattered psammomatous microcalcification. Tumor cells demonstrate perinuclear cytoplasmic clearing, hyperchromatic round-to-oval nuclei with vesicular chromatin and inconspicuous nucleoli. There is prominent secondary structuring with perineuronal satellitosis and subpial condensation of tumor cells. There are up to 8 mitoses per 10 hpf. No necrosis or microvascular proliferation are seen.
Immunohistochemical results show tumor cells stain:
IDH-1 Positive (mutated)
ATRX Positive (not mutated)
MGMT Negative (likely methylated)
Topoisomerase proliferation index 10%.
1p19q codeletion detected.
Oligodendroglioma, IDH-mutant, and 1p/19q-codeleted (WHO CNS5 grade 3)
As of the 2016 WHO classification of CNS tumors to be designated an oligodendroglioma a tumor must be shown to have both IDH mutation and 1p19q codeletion. Also note, that an oligodendroglioma cannot ever be called a glioblastoma.