Systemic onset juvenile idiopathic arthritis is the most chronic rheumatologic disease of childhood. Diagnostic criteria includes arthritis and intermittent fever which continues at least two weeks, accompanying with one of the following: pale erithematous macular rash, generalized lymphadenopathy, hepatosyplenomegaly or serositis. Complications of systemic juvenile idiopathic arthritis are osteopenia, osteoporosis, growth retardation, erosive arthritis, amiloidosis and potentially fatal macrophage activation syndrome. In some cases, the macrophage activation syndrome may be simultaneous with the diagnosis of the disease and early recognition and treatment is life-saving. Here, a 2.5-year-old girl who presented with systemic juvenile idiopathic arthritis and signs of macrophage activation syndrome was presented to emphasize the importance of early diagnosis and treatment.

Keywords: child, macrophage activation syndrome, systemic juvenile idiopathic arthritis