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Washington University Experience | NEOPLASMS (GLIAL) | Oligodendroglioma - IDH1 mutant, del 1p19q - Grade 3 | 3B1 Oligodendroglioma, anaplastic, WHO Grade 3 (Case 3) H&E WM

3B1-7 Sections show a cellular neoplasm organized into infiltrating sheets that involve the white matter and cortex. In the portions of the tumor involving the cortex, numerous examples of neuronal satellitosis are seen. There is no evidence of vascular proliferation or necrosis. A portion of the tumor has very dense cellularity with crowded cell nuclei. The tumor cell nuclei are rounded with speckled chromatin and have a perinuclear clearing in the cytoplasm. The cytological features between the two areas are very similar and a short gradual transition can be appreciated between the two. In the less dense areas few mitoses are seen, however in the hypercellular area the mitotic rate is significant with 13 mitoses/10HPF.

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