A case of incomplete Kawasaki disease with extremely high serum ferritin and interleukin-18 levels

Background The clinical features and laboratory parameters of patients with Kawasaki disease (KD) and systemic juvenile idiopathic arthritis (sJIA) occasionally overlap. Therefore, serum levels of cytokine and ferritin are used as markers to distinguish between KD and sJIA. KD patients have a high level of interleukin (IL)-6, low level of IL-18, and no elevation of the level of serum ferritin. Conversely, sJIA patients have a low level of IL-6 and high levels of IL-18 and ferritin in the serum. However, to the best of our knowledge, no case report of KD with a low serum level of IL-6 and extremely high levels of IL-18 and ferritin is found.