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Washington University Experience | NEOPLASMS (GLIAL) | Oligodendroglioma - IDH1 mutant, del 1p19q - Grade 3 | 22A4 Oligodendroglioma, focal anaplastic (Case 22) H&E 10X
H&E stained sections show a markedly cellular, diffusely infiltrative oligodendroglia glioma. There are foci of marked hypercellularity and greater pleomorphism. In the hypercellular areas, there is rare incipient microvascular proliferation. Mitoses are brisk, up to 7/10HPF. There is no definitive necrosis. ---- Not shown: The tumor is positive for the mutant form of IDH1 (R132H). ATRX expression is retained in tumor cell nuclei. P53 highlights rare tumor cells. The Ki-67 proliferation index is estimated to be up to 10% in the hypercellular areas. Fluorescence in situ hybridization studies (G22-4826) are positive for 1p/19q co-deletion. The collective features are consistent with a diagnosis of oligodendroglioma, IDH-mutant and 1p/19q-codeleted, WHO grade 3. The grade 3 designation is applied based on mitotic count.
