Macrophage Activation Syndrome (MAS)

Laboratory Features

• 1) Cytopenias 2) Abnormal liver function tests 3) Coagulopathy (hypofibrinogenemia) 4) Decreased erythrocyte sedimentation rate 5) Hypertriglyceridemia 6) Hyponatremia 7) Hypoalbuminemia 8) Hyperferritinemia 9) Elevated sCD25 and sCD163

Clinical Features

• 1. Nonremitting fever 2) Hepatomegaly 3) Splenomegaly 4) Lymphadenopathy 5) Hemorrhages 6) Central nervous system dysfunction (headache, seizures, lethargy, coma, disorientation)

Histopathologic Features

• 1) Macrophage hemophagocytosis in the bone marrow aspirate 2) Increased CD163 staining of the bone marrow

Proposed Criteria for MAS in SJIA

• 1) Serum ferritin >684 ng/mL and 2) Any 2 of the following: • Thrombocytopenia (≤181 × 109/L) • Elevated liver enzymes (aspartate transaminase >48 U/L) • Hypertriglyceridemia (>156mg/dL) • Hypofibrinogenemia (≤360 mg/dL)