Myelin oligodendrocyte glycoprotein antibody-associated disease/paediatric multiple sclerosis overlap: a diagnostic conundrum.

While advancements in the classification of acquired demyelinating syndromes have significantly benefited children with this condition, some cases present with overlapping features, posing diagnostic challenges. We describe an Asian girl of early childhood age with acute visual loss. Examination revealed right optic neuritis, left optic nerve atrophy and demyelinating lesions in the juxtacortical brain parenchyma. Anti-myelin oligodendrocyte glycoprotein antibody was elevated, while oligoclonal bands and anti-aquaporin 4 antibody were negative. The patient met the 2023 International Diagnostic Criteria for Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) and, concurrently, potentially fulfilled the 2013 International Pediatric Multiple Sclerosis Study Group criteria for paediatric multiple sclerosis (MS). The primary diagnosis was MOGAD, with paediatric MS considered as a possibility. Corticosteroid treatment improved vision, with no recurrence over 6 months without disease-modifying therapy. Both optic fundi showed atrophy 3 months after the acute phase, but the visual acuity was normal in both eyes, further raising the possibility of MOGAD over paediatric MS. This case highlights the diagnostic complexities in paediatric acute demyelinating syndromes, demonstrating potential overlap between MOGAD and MS diagnoses in children.