Neuro-Oncology Advances 4(1), 1–5, 2022 | https://doi.org/10.1093/noajnl/vdac170 | Advance Access date 25 October 2022 1 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. © The Author(s) 2022. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology. Chelsea Howie, Tahani Ahmad, Kathryn McFadden, Bruce Crooks, P. Daniel McNeely, Simon Walling, Robert Rutledge, Felix Sahm , Felix Hinz, Nada Jabado, Mark Kieran, and Craig Erker Department of Pediatrics, IWK Health, Halifax, Nova Scotia, Canada (C.H.); Department of Diagnostic Radiology, IWK Health, Halifax, Nova Scotia, Canada (T.A.); Department of Pathology, IWK Health, Halifax, Nova Scotia, Canada (K.M.); Division of Hematology/Oncology, Department of Pediatrics, IWK Health, Halifax, Nova Scotia, Canada (B.C, C.E.); Division of Neurosurgery, Department of Surgery, IWK Health, Halifax, Nova Scotia, Canada (P.D.M., S.W.); Department of Radiation Oncology, Dalhousie University, Halifax, Nova Scotia, Canada (R.R.); Department of Neuropathology, Institute of Pathology, Ruprecht-Karls-University, Heidelberg, Germany (F.S.); Clinical Cooperation Unit Neuropathology, German Cancer Research Center, German Cancer Consortium, Heidelberg, Germany (F.S.); Hopp Children’s Cancer Center, NCT Heidelberg, Heidelberg, Germany (F.S.); Department of Neuropathology, Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany (F.H.); Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), German Consortium for Translational Cancer Research (DKTK), Heidelberg, Germany (F.H.); Quantitative Life Sciences, McGill University, Montreal, Quebec, Canada (N.J.); Department of Human Genetics, McGill University, Montreal, Quebec, Canada (N.J.); Department of Pediatric Oncology, Children’s Cancer Hospital Egypt, Cario, Egypt (M.K.) Corresponding Author: Craig Erker, MD, MS, Department of Pediatrics, Division of Hematology/Oncology, IWK Health Centre, 5850/5980 University Avenue, Halifax, NS B3K 6R8, Canada (craig.erker@iwk.nshealth.ca). Diffuse glioneuronal tumors with oligodendroglioma-like features and nuclear clusters (DGONC) are rare tumors of the central nervous system, having been added as a provi- sional diagnosis in the 2021 World Health Organization (WHO) Classifcation of Tumors of the central nervous system (CNS). 1 Retrospective studies report that these are most often mis- diagnosed and treated as high-grade tumors of the CNS. 2,3 However, this entity has demonstrated superior long-term survival in comparison. Given its novelty, there is currently no standard of care. We describe the diagnostic challenges, mo- lecular characteristics, prospective management, and outcome of a pediatric patient with a DGONC, with the aim to increase awareness of this entity and describe clinical behavior and di- agnostic uncertainties. Case Presentation A 6-year-old male presented with a 2-year history of intermit- tent vomiting that increased in frequency over the preceding 3 months. Additionally, there was an approximate 18-month history of episodes consisting of breath-holding, shaking of hands, vacant staring, and non-sensical speech each lasting about 20–45 s before resolution, and though initially responsive during the episodes, he became progressively less responsive as time went on. The patient presented to their local emergency department after what was determined to be a focal seizure lasting less than 40 seconds. He had 3 to 4 similar seizures over the following 2 days and was started on antiepileptics. Shortly after, he developed an ataxic gait which prompted neuroimaging demonstrating a right hemispheric tumor with midline shift and mass effect. Clinical Course Initial MRI showed a large, well-defned intraparenchymal mass lesion involving the right frontal and temporal lobes. There was complete encasement of the right middle cerebral artery (MCA). There was no peritumoral edema, no enhance- ment, and no restricted diffusion. There were no fndings of distant or regional metastases. The MRI features suggested a low-grade lesion (Figure 1a–d). The patient underwent a frontotemporal craniotomy with a resultant subtotal resection limited due to the MCA (Figure 1e). Postoperatively, he had an uncomplicated recovery. The histopathology of the initial surgical resection was in- itially thought to be consistent with a high-grade glioma. Diagnostics and prospective outcome of a diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters after surgical resection (DGONC): a case report