Figure 2.

(A) Hematoxylin and eosin–stained sections reveal a hypercellular neoplasm with widespread perivascular pseudo-rosette formation, characteristic of ependymoma (100× magnification). (B) Many regions of the ependymoma are hypercellular and harbor brisk mitotic activity, supporting a diagnosis of anaplastic ependymoma (400× magnification). (C) Ependymoma cells show widespread loss of expression of H3K27me3, and expression is retained in endothelial cells serving as positive internal controls (200× magnification).