There are several diseases that present with symptoms similar to AHEM, including myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorder, neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis, infectious meningoencephalitis, vasculitis, progressive multifocal leukoencephalopathy (PML), Behçet syndrome and lymphomatoid granulomatosis [1,2]. Here, OMG is linked to progressive multifocal leukoencephalopathy.