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Washington University Experience | NEOPLASMS (EMBRYONAL) | Medulloblastoma, Histologically Defined | Classic Subtype | 9B1 Medulloblastoma (Case 9) H&E 3

9B1-4 Fragments of brain parenchyma are involved by a moderate to highly cellular neoplasm. There is mild to moderate nuclear pleomorphism, with the majority of tumor cells containing oval to irregular hyperchromatic nuclei with minimal discernible cytoplasm. There are hypercellular nodules with smaller, more hyperchromatic nuclei, sometimes surrounding central collections of neuropil, i.e., Homer Wright rosettes. The mitotic index is brisk and there are scattered pyknotic cells. There are foci of tumor necrosis and microvascular proliferation is evident.

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