There is a growing body of literature and scientific discovery on pediatric autoimmune encephalitides. This is a heterogenous group of neuroinflammatory conditions leading to often perplexing acute and progressive neurologic and/or neuropsychiatric symptoms. This report demonstrates the evaluation and management of an adolescent with myelin-oligodendrocyte glycoprotein (MOG) antibody-associated fulminant acute disseminated encephalomyelitis (ADEM) in the context of current literature. The featured magnetic resonance imaging uniquely highlights progressive central nervous system lesions detected over the course of the first week of disease.TopicsEncephalitis, encephalopathy, ADEM, MOG.