In MS, biomarkers aid in early diagnosis,improving patient care, and disease management. Among various cerebrospinal fluid (CSF)/serum biomarkers,Chitinase 3-like 1 (CHI3L1), also known as YKL-40, has recently emergedas a potential biomarker for MS. The expressionof CHI3L1 has been found to be higher in the CSF of individuals withMS. Here, CHI3L1 is linked to myeloid sarcoma.