An overtly inflammatory CSF cytokine profile is associated with a more severe MS at presentation and follow-up, and pathologically, is linked to subpial tissue damage in a gradient-like pattern, which can be replicated in experimental models by the induced expression of inflammatory cytokines in the leptomeninges (Magliozzi et al., 2010, 2018, 2020; Gardner et al., 2013; James Bates et al., 2022). The gene discussed is CSF2; the disease is myeloid sarcoma.