Furthermore, astrocytic chitinase 3-like 1 (CHI3L1) expression, associated with chronic inflammation and neurotoxicity (Cantó et al., 2012; Matute-Blanch et al., 2020), is observed in chronic MS lesions but absent from other lesion types (Cantó et al., 2012). This evidence concerns the gene CHI3L1 and myeloid sarcoma.