The diagnosis of MAS in a patient known to have a rheumatic disease must be suspected when the patient shows signs of systemic derangement, fever, hepatosplenomegaly, bleeding tendency, leukopenia, thrombocytopenia, increase in liver enzyme values and coagulations disturbance [12] . Hypofibrinogenemia is one of the most important clues for the diagnosis of MAS since patients usually have high fibrinogen levels due to their underlying inflammatory disease. An increased fibrinolysis is most probably due to uncontrolled activation of the macrophages and the production of plasminogen. A decrease in factor II and factor VII + X values is also observed in some reported cases [13] . A bone marrow smear may show macrophage hemophagocytosis. Another biological indicator of MAS is an increased level of serum triglyceride that can be related to the patient's extensive production of cytokines, such as tumor necrosis factor alpha, which reduce the lipoprotein lipase activity. Interleukin-1 and interferon gamma are also overproduced in a patient with MAS [1] .