CXCL9 and Hemophagocytosis: The current diagnostic criteria for HLH/MAS employs the use of five out of nine of the following findings: fever ≥ 38.5 °C; splenomegaly; cytopenia in ≥ two blood lineages; hypertriglyceridemia; hypofibrinogenemia; hemophagocytosis in the bone marrow, spleen, lymph node, or liver, ferritin > 500 ng/mL (although >3,000 ng/mL is more indicative of HLH); low or absent NK elevated sCD25; and elevated CXCL9 [2].