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Washington University Experience | NEOPLASMS (GLIAL) | Oligodendroglioma - IDH1 mutant, del 1p19q - Grade 3 | 3F Oligodendroglioma, anaplastic, WHO Grade 3 (Case 3) SYN 6

Synaptophysin shows a dotlike positive staining pattern in the hypercellular region and also highlights entrapped neuronal elements. ---- Comment: The morphological, immunohistochemical, and molecular features of this tumor are diagnostic of an anaplastic oligodendroglioma (WHO Grade 3). The FISH studies show codeletion of 1p/19q in this case. Though immunohistochemistry for EGFR showed positive staining (a qualitative method), in this case there was no gene amplification by FISH (a quantitative method) and is considered the more reliable evaluation.

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