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Washington University Experience | NEOPLASMS (EMBRYONAL) | ATRT - Atypical Teratoid Rhabdoid Tumor | 15C2 ATRT (Case 15) 40X BAF47 2

15C1,2 Tumor cells lack INI1 nuclear immunoreactivity compared to endothelial nuclei (INI1 IHC). ---- Immunohistochemical studies were performed and showed polyphenotypic expression within the tumor cells. There is widespread reactivity with vimentin and patchy expression of CAM5.2 and EMA. Scattered tumor cells are immunoreactive with GFAP. There is patchy weak expression of synaptophysin. The tumor has a very high Ki-67 proliferation rate. ---- FISH studies identified chromosome 22q loss.

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