<prompt> Macrophage activation syndrome is most commonly-1 seen in association with?Systemic sclerosisSweets syndromeSLEJuvenile Rheumatoid Ahritis  <response>: Answer is D Juvenile Rheumatoid Ahritis: Macrophage Activation Syndrome is most commonly seen in association with Systemic Onset Juvenile Idiopathic Ahritides Earlier termed JRA and adult-onset Stills Disease. Amongst other autoimnnine diseases, MAS has also been repoed in patients with Juvenile SLE and Kawasaki Disease Rare causes. Macrophage activation syndrome MAS is a life threatening complication of rheumatic diseases thought to be caused by the uncontrolled activation and proliferation of T lymphocytes and well-differentiated macrophages leading to widespread hemophagocytosis and cytokine overproduction. For unknown reasons, occurs much more frequently in systemic juvenile idiopathic ahritis S-JIA and in its adult equivalent, adult-onset Still disease. MAS has also been repoed in other systemic inflammatory disorders, including SLE and Kawasaki disease. The main clinical features of MAS include a high unremitting fever, hepatosplenomegaly, lymphadenopathy, bleeding, rash and central nervous system manifestations. Hyperferritinemia is an impoant laboratory hallmark of Macrophage Activation Syndrome MAS is regarded as a an acquired cause of Haemophagocytic Lymphohistiocytosis HLH 