We performed immunohistochemistry and evaluated CXCL13 expression in lymph nodes collected from 17 iMCD patients (Immunohistochemistry cohort), including nine patients who met validated iMCD-TAFRO criteria12 and eight patients who demonstrated consistency with iMCD-NOS, as well as in patients with reactive lymph nodes that demonstrated some iMCD-like features (N = 17) and RA lymph nodes (N = 9) (representative images Fig. 3a–d). This evidence concerns the gene CXCL13 and rheumatoid arthritis.