Fig. 2

a Photomicrographs showing sections of tumor tissue composed of sheets of oligodendrogioma-like cells with round to oval nuclei within a clear cytoplasm in a delicate vascular network, intervening neutrophils, calcification, and Homer-Wright Rosettes (H&E, 4×). b, c High power views (H&E, 10×) showing necrosis, microvascular proliferation, several mitoses, and areas of hemorrhage. d Immunostaining showing diffuse positivity for synaptophysin. e Tumor cells are immunonegative for epithelial membrane antigen (EMA). f Focal positivity seen for glial fibrillary acid protein (GFAP). g Ki-67 labeling index was 8–10%. h Isocitrate dehydrogenase 1 (IDH-1) and i chromogranin were negative on immunostaining. The morphological and immunohistochemical features are those of an atypical neurocytoma