The patient went on to have debulking. 

Histology

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:

• GFAP Negative

• Nestin Low

• NogoA Positive

• IDH-1 Positive (mutated)

• ATRX Positive (not mutated)

• MGMT Negative (likely methylated)

• p16 Positive

• p53 Negative

• Topoisomerase proliferation index 10%.

1p19q codeletion detected. 

FINAL DIAGNOSIS:

Oligodendroglioma, IDH-mutant, and 1p/19q-codeleted (WHO CNS5 grade 3)

Discussion

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.