Spinal cord diffuse midline glioma (DMG) with H3 K27-alteration is a group of spinal cord high-grade glioma with poor outcome. We present a case with rare onset symptom pattern of pediatric spinal DMG, contributing to the understanding of the clinical presentations and natural history of pediatric spinal cord DMG.A 7-year-old boy was admitted due to symptoms of intracranial hypertension without obvious spinal cord-related symptoms. Head radiological examinations, blood and cerebral spinal fluid tests did not support intracranial lesion, infection, or autoimmune diseases. Spinal magnetic resonance imaging revealed intraspinal occupying lesion with leptomeningeal dissemination. Pathology of the lesion verified DMG with H3 K27M-alteration.Pediatric DMG with leptomeningeal dissemination could present with initial symptoms of intracranial hypertension without obvious spinal cord-related symptoms. Spinal cord examinations in cases of intracranial hypertension with negative head radiological examination results could be valuable in finding the etiology.© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.