Macrophage activation syndrome.

There are no laid down criteria for the diagnosis of MAS. The diagnostic criteria laid down by Histiocyte Society to diagnose HLH are generally applied to the diagnosis of MAS.5 These consist of clinical features (fever, hepato-splenomegaly) along with laboratory features of cytopenia involving at least 2 cell lineages in the peripheral blood (Hb < 9 gm/dl, neutrophils < 1,000/mm3, and platelets < 1,00,000/ mm3), hypertriglyceridaemia (≥ 160 mg/dl), and hypofibrinogenaemia (≤ 250 mg/dl), coupled with demonstration of haemophagocytosis in bone-marrow, spleen or lymph nodes. Bone-marrow may not always reveal haemophagocytosis, when the process may either be seen in other tissues (spleen, lymph nodes) or in repeat bone-marrow examinations. Rivalli, based on review of literature, found serum ferritin (> 1000 mg/dl), triglycerides (> 160 mg/dl), and fibrinogen (< 250 mg/dl) to be markers with highest sensitivity and specificity for the diagnosis of MAS.6