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Washington University Experience | NEOPLASMS (GLIAL) | Oligodendroglioma - Histologically Defined (most del 1p19q) | 15A4 Oligodendroglioma, Grade 2 1p19q del (Case 15) H&E 10

There is prominent formation of secondary structures with tumor satellitosis around neurons and subpial tumor aggregates. Occasional mitotic figures are seen with 2 mitoses/10HPF. There is no microvascular proliferation or necrosis.---- Not shown: The Ki-67 labeling index is focally high, reaching 16.8%. The morphologic and immunohistochemical features are consistent with the diagnosis of oligodendroglioma, WHO grade 2. In some areas, the degree of nuclear atypia, along with the slightly increased proliferative index is worrisome for a higher grade component. However, this tumor does not meet strict criteria for an anaplastic designation "WHO grade 3". In this particular case, there is evidence of deletions of both 1p and 19q, ----

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