CXCL13 and myeloid sarcoma: It is known that B cells play a pathogenic role in MS both through the production of antibodies in the CNS and the release of proinflammatory factors in the CSF (Li et al., 2018; Sabatino et al., 2019), such as cytokines [tumor necrosis factor (TNF), interferon IFN (IFNγ), interleukin 6 (IL-6), IL-10, IL-34, IL-35, and granulocyte–macrophage colony-stimulating factor (GM-CSF)] and lymphoid chemokines (CXCL10, CXCL12, CXCL13) (Gardner et al., 2013; Li et al., 2015; Magliozzi et al., 2018).