[Case of systemic-onset juvenile idiopathic arthritis complicated with sepsis --usefulness of cytokine profile for the differentiation between macrophage activation syndrome and sepsis].

The differential diagnosis of macrophage activation syndrome (MAS) and sepsis must be considered in the clinical course of systemic-onset juvenile idiopathic arthritis (s-JIA) with sudden onset of high-grade fever and abnormal laboratory findings, including leukocytopenia, thrombocytopenia, and coagulopathy. In this report, we describe the case of a 17-month-old girl diagnosed with s-JIA complicated with sepsis. Her serum interleukin (IL)-18 level was significantly elevated throughout the clinical course. Furthermore, compared to other MAS patients, she showed a significantly elevated serum IL-6 level and procalcitonin in sepsis. Therefore, our results suggest that a patient's cytokine profile may be a useful indicator of disease activity and may thus help in the differential diagnosis of sepsis and MAS in s-JIA.