Following an infection, the immune system is activated, leading to the activation of a large number of lymphocytes that release cytokines such as interleukin (IL)-4, IL-6, IL-10, IL-13, and transforming growth factor-β.[8–10] This results in an abnormal immune response, leading to characteristic organ fibrosis and plasma cell infiltration.[11] IgG4-RD is generally characterized by plasma cell infiltration in affected organs, elevated serum IgG4 levels, and chronic fibrosis, but its clinical manifestations are diverse, often leading to misdiagnosis as infections or tumors. The gene discussed is IL6; the disease is infection.