Macrophage activation syndrome in a newborn infant born to a untreated mother with adult onset still disease

Methods We reported a newborn infant with macrophage activation syndrome (MAS) born from a mother with positive antinuclear (ANA) and anti-SSA/Ro antibodies. The 2,500 g girl was born at 37 weeks of gestation in good condition. Mother had been diagnosed with adult onset Still disease 10 years previously. During pregnancy, she did not take any medication as she was free of symptoms. The baby was admitted due to tachypnea and fever 12 hours after birth. Initial laboratory findings showed mild anemia with thrombocytopenia, and mild elevation of alanine aminotransferase (ALT). Anti-platelet antibody was not detected. A work-up of infectious etiology, including agents responsible for congenital infection, was negative.