Macrophage activation syndrome in 13 children with systemic-onset juvenile idiopathic arthritis

Background Macrophage activation syndrome (MAS) is a severe, potentially life-threatening condition induced by chronic rheumatic diseases, especially systemic-onset juvenile idiopathic arthritis (SoJIA) in childhood. This study aimed to analyze the clinical and laboratory characteristics of systemic-onset juvenile idiopathic arthritis (SoJIA) with macrophage activation syndrome (MAS) in 13 patients.