Higher magnification of the previous image shows a hint of rhabdoid features in some of the tumor cells. Immunohistochemically, they are usually reactive for EMA, keratin, GFAP, synaptophysin, and smooth muscle actin. Genetic changes in atypical teratoid/rhabdoid tumor (AT/RT): Majority of the cases show loss of chromosome 22. The tumor suppressor gene underlying the development of AT/RT is hSNF5/INF1 that maps to chromosome 22q11.2. The prognosis is extremely poor with overall survival rate being less than 20%.