AQP4 and myeloid sarcoma: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) has been increasingly recognised as a distinct Central Nervous System (CNS) demyelinating disorder over the past decade, separate from multiple sclerosis (MS) and Aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4+NMOSD).