CXCL13 and myeloid sarcoma: Our findings are in line with the previous reports on the association of CXCL13 to leukocyte CSF counts [20], higher risk of relapse, and CIS conversion to MS [21], as well as with higher disease activity in the WM [22, 23], further suggesting a possible role of CXCL13 as a soluble marker of disease activity or severity in MS.