Systemic arthritis is a subtype of juvenile idiopathic arthritis (JIA) with a frequency of 4-17% in the whole group. Macrophage activation syndrome (MAS) is a serious, potentially life-threatening complication of sJIA, characterized by excessive activation and proliferation of T-lymphocytes and macrophages, resulting in overproduction of proinflammatory cytokines and development of typical clinical-laboratory changes.
The case describes development of MAS in a 7-year-old girl five years after being diagnosed with JIA. A year after the diagnosis the disease became continuously relapsing and non-responsive to treatment neither with synthetic nor with first- and second-line biological disease modifying antirheumatic drugs.
The development of MAS could have been provoked either by the active main disease, the medications used or pneumocyst-caused pneumonia. For the treatment of MAS, high-dose intravenous glucocorticoids and cyclosporine-A were used, which led to the improvement of the process.