Catastrophic adult-onset Still disease (AOSD) is a severe form of AOSD with organ failure. We describe a 27-year-old healthy man who presented with recurrent fevers, a rash, a sore throat, and hepatomegaly, suggestive of AOSD. With worsening disease, he developed a large pericardial effusion with tamponade, requiring a pericardial window. We detail the clinical features of AOSD along with the first description, to our knowledge, of the histopathology of the pericardial tissue and the cytokine analysis of the pericardial fluid.
