Background: Since mid-April 2020, cases of multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease (COVID-19) that mimic Kawasaki disease (KD) have been reported in Europe and North America. However, no cases have been in East Asia, where KD is more prevalent.
Case presentation: A previously healthy 11-year-old boy was admitted with a 4-day history of fever and abdominal pain. He had no contact history to any patient with COVID-19. Blood acute inflammatory markers were highly elevated. He was treated with antibiotics for suspected bacterial enteritis, but he suddenly developed hypotension. Inotropics and intravenous immunoglobulin were administered to manage septic shock. On hospitalization day 6, he developed signs and symptoms of KD (conjunctival injection, strawberry tongue, cracked lip, and coronary artery dilatation) in addition to pleural/pericardial effusion and mesenteric lymphadenitis. The results of microbiologic tests, including reverse-transcription polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were negative. Fluorescent immunoassay and enzyme-linked immunosorbent assay revealed abundant IgG antibodies against SARS-CoV-2 in his serum, but no IgM antibodies. He was discharged successfully on day 13.
Conclusion: MIS-C may occur in children with a previously asymptomatic COVID-19 infection. A high index of suspicion is required for this novel syndrome in unusual cases of KD or KD shock syndrome with multisystem inflammation, even when there is no clear history of contact or symptoms of COVID-19.