DISP-12. Diagnostic clues to central nervous system (CNS) tumors in children with developmental delay: a case for system-level change

Abstract Diffuse midline glioma (DMG), H3 K27M, is an aggressive WHO grade IV CNS lesion of the pons, thalamus, or spine with a median survival of 8-12 months, predominantly in children.1-6 While pontine tumors often present with cranial nerve deficits, long tract signs, and cerebellar dysfunction,6-8 presentation in children with developmental delay can be subtle. Early signs, such as gait abnormalities or impaired speech, may be misattributed to underlying neurodevelopmental disorders. This case highlights proposed systemic changes to improve early detection of primary CNS tumors, emphasizing known risk factors and access to care. We present a 4-year-old girl with autism spectrum disorder, developmental delay, and longstanding gait abnormalities who presented with two weeks of worsening gait, refractory to six months of physical therapy. Since walking began at 17 months, she exhibited a left foot drop and limited echolalic speech. Examination revealed bilateral lower extremity hyperreflexia, a left Babinski sign, and a wide-based, left-leaning shuffling gait. Neuroimaging identified a pontine mass, with biopsy confirming DMG, H3 K27M, CNS WHO grade IV. She died 2.5 months later. This case highlights the diagnostic challenge of distinguishing neurodevelopmental disorders from neurological malignancies. In nonverbal children without regular medical care, diagnosis is often delayed. Thus, clinicians must maintain a high index of suspicion for neurological pathology in children with developmental delays and focal neurological signs, particularly when healthcare access is limited. Neuroimaging indications include focal neurologic symptoms and developmental regression. Improving early detection and management requires broader access to evaluation and imaging, supported by public education, primary and specialty care access, and streamlined referral systems. While DMG remains incurable, earlier diagnosis may allow families meaningful time together and advance research.