AQP4 and myeloid sarcoma: Several recent studies have identified the presence of anti-myelin oligodendrocyte glycoprotein antibodies (MOG-Ab) in the serum of children and adults with various IDD, including AQP4-Ab negative NMOSD, acute disseminated encephalomyelitis (ADEM), idiopathic optic neuritis, idiopathic myelitis, and atypical MS [8–32].