To the Editor:
We read with interest the well-founded observation made by Yung et al regarding no change in epidemiology or cases of Kawasaki disease in Singapore amid the current ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. When it was initially recognized, there was uncertainty whether the SARS-CoV-2 associated multisystem inflammatory syndrome in children (MIS-C) represented Kawasaki disease. Evidence and evolving understanding suggest it to be a separate clinical entity.
A recent large multicenter case series from the US and Europe show that 22%-40% of MIS-C cases met either complete or incomplete Kawasaki disease criteria and were either classified as Kawasaki disease or Kawasaki disease shock syndrome.1, 2, 3 The diagnostic criteria for Kawasaki disease and MIS-C are broad because both Kawasaki disease and MIS-C are inflammation-associated syndromes, and there is overlap.
Accumulating literature highlights the similarities and differences between MIS-C and Kawasaki disease.4 Although a case definition for MIS-C was released by the US Centers for Disease Control and Prevention, vastly differing treatment modalities ranging from supportive care to immunomodulating agents and plasma infusion have been implemented with a lack of consensus on how to best treat this condition. Reassuringly, MIS-C thus far has been associated with low mortality.
Our study was designed to include critically ill children and adolescents who met criteria for SARS-CoV-2 associated MIS-C. Some patients in our series also may have met Kawasaki disease criteria. Whether “overlap” patients have Kawasaki disease, atypical Kawasaki disease, Kawasaki disease with macrophage activation syndrome, or represent a spectrum of MIS-C requires ongoing surveillance and longer term follow-up.
Footnotes
The authors declare no conflicts of interest.
References
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