Ewing Sarcoma of the Posterior Fossa in an Adolescent Girl

Figure 2

(a) Diffuse sheets of tumor cells. H&E, ×20. (b, c) Tumor cells with scanty cytoplasm and round to ovoid nuclei infiltrating the bone. H&E, ×40. (d) High amount of glycogen in the tumor cells by granular PAS positivity. PAS, ×40. (e) Membraneous expression of neuronal marker CD99. ABC, ×40. (f) Split signal of EWRS1 gene located in the tumor cells (arrows). FISH technique, ×100.

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