Macrophage activation syndrome in Kawasaki disease.

BACKGROUND: Kawasaki disease is an acute febrile vasculitis of childhood. Macrophage activation syndrome is a rare life threatening complication. CASE CHARACTERISTICS: 4-year-old boy with Kawasaki Disease treated with intravenous immunoglobulins. OBSERVATION: He developed encephalopathy, hepatosplenomegaly and pancytopenia. Blood investigations and bone marrow aspiration suggested macrophage activation syndrome. OUTCOME: Good response to pulse methylprednisolone (30 mg/kg/d) for 5 days. MESSAGE: Macrophage activation syndrome may complicate Kawasaki disease.