Macrophage activation syndrome in childhood rheumatic diseases

Macrophage activation syndrome (MAS) is a life-threatening complication of systemic inflammatory disorders that is thought to be caused by the activation and uncontrolled proliferation of T lymphocytes and macrophages, leading to widespread hemophagocytosis and cytokine overproduction. Recent findings in hemophagocytic lymphohistiocytosis, a disease that is clinically very similar to MAS, highlight the possible pathogenetic role of a defective function of cytotoxic lymphocytes. Prompt diagnosis is important and recently preliminary diagnostic guidelines for the syndrome have been proposed. The recognition that MAS belongs to the secondary or reactive hemophagocytic syndromes has led to propose to rename it according to the contemporary classification of histiocytic disorders. Cyclosporine A has been found to be effective in patients with corticosteroid resistant MAS.