Acquired demyelination of the central nervous system in children can manifest as multiple sclerosis, neuromyelitis optica, myelin oligodendrocyte glycoprotein (MOG)-associated demyelination, or as an acute monophasic illness without serum antibodies. Rarely do patients with demyelinating disease need surgical intervention for fulminant crises.We report a case of anti-MOG antibody-related tumefactive demyelination in a 10-year-old female who required urgent hemicraniectomy and external ventricular drain placement for progressive white matter edema with obstructive hydrocephalus, subfalcine, and transtentorial herniation.