Abstract
Trisomy 21 is sometimes complicated by congenital heart disease; however, comorbid type I diabetes mellitus and diseases involving autoantibodies such as Hashimoto's disease and Graves' disease are not uncommon. In contrast, autoinflammatory diseases such as Kawasaki disease and systemic juvenile idiopathic arthritis are rarely observed. We report a rare case of trisomy 21 with systemic juvenile idiopathic arthritis that responded well to the first course of methylprednisolone pulse therapy, but flared up and was complicated by macrophage activation syndrome (MAS). Subsequent methylprednisolone pulse therapy and cyclosporine resolved this condition. Cytokine analyses at several time points during the clinical course revealed that interleukin-18, interleukin-6, and chemokine ligand 9 levels were elevated even MAS onset in the patient with trisomy 21 once the clinical symptoms seemed to have settled down. Thus, in the future, early analysis of cytokine profiles should be performed for risk assessments of MAS and for determining the treatment intensity, even T21 patients.
