Microglial/macrophage activation can be revealed by sCD14, sCD163, and YKL‐40 expression; these biomarkers have well‐known implications in brain diseases, such as MS, intracranial infections, and neurodegenerative diseases (Bonneh‐Barkay et al., 2010; Dheen et al., 2007), However, little is known about these biomarkers in NMOSD. Here, CHI3L1 is linked to myeloid sarcoma.