CRP and macrophage activation syndrome: Clinical features which may predict the onset of MAS include high-grade fever, hepato-splenomegaly, cytopenias, hyperferritinemia, elevated c-reactive protein (CRP) with falling erythrocyte sedimentation rate (ESR) (due to hypofibrinogenemia) and hemophagocytosis identified in the bone marrow or in other tissues of the reticuloendothelial system [1].