Macrophage Activation Syndrome (MAS) Classified among the secondary or acquired forms of haemophagocytic lymphohistiocytosis (sHLH) What? A subset of hemophagocytic lymphohistiocytosis (HLH) that develops on the background of a highly inflammatory disease How? Excessive release of pro-inflammatory cytokines, such as IL-1 and IL-6, leading to widespread inflammation via hemophagocytosis and cytokine overproduction. Where? Seen in: • Systemic juvenile idiopathic arthritis (sJIA) • Adult-onset Still disease • Systemic lupus erythematosus • Kawasaki disease • Periodic fever syndromes Clinical Presentation: • Rapid development of multiorgan failure • Fever is the main clinical manifestation of MAS - Nonremitting fever • Hepatosplenomegaly and generalized lymphadenopathy • Central nervous system (CNS) dysfunction • Hemorrhagic manifestations: from easy bruising to purpura to mucosal bleeding (Petechial or purpuric rash) • Heart, lung, and kidney failure DDX: • Flare of underlying disease (eg, systemic juvenile idiopathic arthritis [SJIA], systemic lupus erythematosus [SLE], AOSD) • Infection (eg, visceral leishmaniasis, brucellosis) • Sepsis • Drug-induced hypersensitivity syndromes • HLH Labs: • Profound cytopenia with leukopenia, anemia, and thrombocytopenia • Liver function tests ↑ AST ↑ ALT ↑ bilirubin level • Hypoalbuminemia • Hypofibrinogenemia • ↑ PT ↑ PTT • ↑ Fibrin degradation products • ↑ D-dimers • ↑ Triglycerides • ↑ Lactate dehydrogenase • ↑ Ferritin > 5000 to 10,000 ng/mL • Hyponatremia • Increased soluble IL-2 receptor alpha (or soluble CD25) • Increased soluble CD163 • Histopathologic features • Macrophage hemophagocytosis in the bone marrow • Increased CD163 staining of bone marrow Histopathologic criteria: Evidence of macrophage hemophagocytosis is found in the bone marrow aspirate sample. Treatment: • Corticosteroids • IVIG • Cyclophosphamide • Plasma exchange #MAS #Macrophage #Activation #Syndrome #Diagnosis #Management #Hematology #Rheumatology
