Spectre of COVID-19 infection confounding myocarditis related to cytomegalovirus mononucleosis syndrome and hyperinflammatory syndrome

Viral infections have multiple mechanisms of affecting internal and external organs by direct invasion or by molecular mimicry. They have also been described as triggers for inflammatory processes like hyperinflammatory syndrome (HIS), Adult-onset Stills Disease (AOSD), and myocarditis [1]. Here we report an interesting case of a young adult with recent infection with SARS-CoV-2 (COVID-19) who presented with myocarditis requiring circulatory support in the cardiac care unit. During the admission, he was found to have concurrent cytomegalovirus (CMV) mononucleosis syndrome and presentation consistent with HIS resembling AOSD. This patient had multiple etiologies that could have caused myocarditis: CMV infection, COVID-19 infection, and HIS. As noted, viral infections have been proposed as potential triggers for the onset of HIS and AOSD with unknown mechanisms. We aim to add to the literature regarding CMV infection in an immunocompetent host causing myocarditis and HIS with features of AOSD with recent history of COVID-19 infection.