Macrophage activation syndrome II/II

Macrophage activation syndrome (MAS) is a rare systemic disorder which results from uncontrolled activation and proliferation of T cells and excessive activation of macrophages. Primary haemophagocytic lymphohistiocytosis (HLH) is recognized as having a genetic basis, but the secondary haemophagocytic syndrome (HS), also referred to as MAS, occurs in a number of autoimmune disorders including systemic onset juvenile idiopathic arthritis, systemic lupus erythematosus (SLE), adult onset Still's disease and other disorders. In this second of the two part series, the clinical features and management are described.