Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease Mimicking Central Nervous System Infection in an Adolescent: A Case Report

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) can resemble central nervous system infection in children because fever, headache, vomiting, cerebrospinal fluid pleocytosis, and multifocal brain lesions may coexist. We report a previously healthy 13-year-old boy who developed headache, fever, vomiting, and binocular horizontal diplopia. Examination showed transient exotropia with apparent adduction limitation but no encephalopathy, seizures, limb weakness, pupillary abnormality, optic neuritis, or spinal cord lesion. Cerebrospinal fluid showed mononuclear-predominant pleocytosis with mildly elevated protein. Brain magnetic resonance imaging showed evolving patchy fluid-attenuated inversion recovery hyperintensities in the right temporal lobe, basal ganglia, periventricular region adjacent to the fourth ventricle, and later the right frontal lobe. Extensive microbiological testing was unrevealing. Serum myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) was repeatedly positive by live cell-based assay, whereas aquaporin-4 immunoglobulin G (AQP4-IgG) and autoimmune encephalitis antibodies were negative. Clinical improvement occurred during overlapping treatment with intravenous immunoglobulin and corticosteroids. On illness day 97, during prednisone tapering following an individualized off-label decision to use rituximab, the patient remained clinically stable. This case highlights that pediatric MOGAD should be considered when an infection-like central nervous system presentation is accompanied by evolving multifocal magnetic resonance imaging abnormalities and negative pathogen studies. Diplopia can be an important focal clue; however, because the ocular motor examination was incomplete, internuclear ophthalmoplegia could not be confirmed.