MICROSCOPIC DESCRIPTION: Paraffin sections show a moderately hypercellular tumor. This is composed of cells with neurocytic morphological features - small round hyperchromatic nuclei with delicate processes that are strongly immunopositive for synaptophysin. There are arranged in columns in association with small capillary vascular channels and GFAP positive glial cells forming glioneuronal elements. These enclose collections of myxomatous/mucinous material in which scattered "floatinmg" neurons are noted. These are highlighted by NeuN immunostaining. No mitotic figures or areas of necrosis are identified. No immunostaining for IDH-1 R132H is seen. Immunostaining for ATRX and p16CDKN2A is preserved. The topoisomerase labeling index is approximately 2%. The features are of dysembryoplastic neuroepithelial tumor (DNET).