Abstract
A 46-year-old man presented with progressive painful monocular vision loss and left leg paresthesias. Workup demonstrated multifocal demyelinating lesions and CSF-restricted oligoclonal bands. He was diagnosed with multiple sclerosis (MS), but follow-up testing was notable for positive myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG). We discuss implications and clinical considerations for MOG-IgG positivity in MS.