Multisystem inflammatory syndrome in adults (MIS-A) is a rare and emerging syndrome after coronavirus disease 2019 (COVID-19). To the best of our knowledge, Japanese cases of MIS-A are rarely reported. Here, we describe a case of MIS-A in a 44-year-old Japanese woman presenting with multiorgan dysfunction (i.e., cardiovascular and mucocutaneous involvement) and markedly elevated inflammatory markers 2 weeks after recovery from COVID-19. Treatment with intravenous immunoglobulins and corticosteroids resolved her symptoms. On the 13th day, she was discharged from the hospital with no recurrences on follow-up. This study highlights the importance of recognizing this emerging syndrome when treating patients with multiorgan dysfunction after COVID-19.

Few cases of acute respiratory distress syndrome (ARDS) in severe fever with thrombocytopenia syndrome (SFTS) have been treated with venovenous extracorporeal membrane oxygenation (VV-ECMO), and its role remains unclear. A 73-year-old Japanese woman presented with multiple organ failure (MOF) due to SFTS, including liver, neural, hematologic, renal, and ARDS. VV-ECMO for refractory hypoxemia under lungprotective ventilation with prone positioning led to gradual respiratory improvement, and she was successfully weaned on the 19th day of hospitalization. However, she died from persistent MOF on the 60th day of hospitalization. VV-ECMO contributed to recovery from ARDS but not from the ultimate cause of death, i.e., MOF. SFTS could have variable MOFs with different disease trajectories, which influence the decision for VV-ECMO.