Fig. 2

Histology of neuroepithelial tumors with EWSR1-PLAGL1 rearrangement. Concurrent ependymal and ganglionic differentiation was observed on initial resection in 4/6 cases with EWSR1-PLAGL1 rearrangement in this series. The most prominent example occurred in a tumor with combined ependymoma/subependymoma-like histology (Case #4) including areas with intermixed clusters of ganglion cells (A–E). Paranuclear dot-like staining for EMA was only convincingly present in Case #4 (B). Case #5 also showed lower-grade histologic features and had interspersed dysmorphic ganglion cells of low to moderate frequency among otherwise subtly ependymal-like histology; the ganglion cells were small in size (F–G). Case #3 contained ganglion cells in regions of lower-cellularity with occasional microcalcifications, the adjacent areas with greater ependymal quality showed smaller sized cells and variable cellularity (H–I). Case #6 was predominantly ependymal-like with focal areas containing ganglionic cells, there was regionally increased cellularity (J–K). Case #1 lacked a ganglion cell component on initial resection, and showed higher-grade histologic features with increased cellularity (L), elevated Ki-67 labeling and mitotic index, as well as areas of necrosis