Serum interleukin-18 provides a clue to the diagnosis of adult-onset Still's disease: findings from 6 Japanese patients with adult-onset Still's disease.

Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disorder accompanied by skin eruption. However, typical skin eruptions, such as evanescent, salmon-pink erythema, are not specific to AOSD and dermatologists often face difficulty in diagnosing AOSD. Interleukin-18 (IL-18) is believed to be the initiating factor of the inflammatory cascade in AOSD and overproduction of IL-18 contributes to the development of systemic autoinflammatory reactions. Therefore, we examined serum IL-18 levels in the active and inactive phase of 6 Japanese patients with AOSD who visited our dermatology clinic over the past 10 years and compared with other markers, including IL-6, ferritin and C-reactive protein.