SARS-CoV-2 infection in the context of Kawasaki disease and multisystem inflammatory syndrome in children

Recent studies have noted an increasing number of Kawasaki-like cases in the pediatric population following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In the literature, the condition is described as multiple inflammatory syndrome in children (MIS-C) or pediatric inflammatory syndrome (PIMS). A similar clinical course of Kawasaki disease (KD) and MIS-C causes difficulties in distinguishing between both conditions. However, the differential diagnosis is crucial since patients with MIS-C can present severe symptoms (myocardial dysfunction, fever, mucocutaneous symptoms) and require more extensive monitoring during treatment than children diagnosed with KD. Along with assessing epidemiological and genetic factors, it is imperative to estimate the risk of developing MIS-C in KD patients with confirmed SARS-CoV-2 infection. Genetic predispositions, such as the ITPKC gene polymorphism in KD, ACE deletion (D) polymorphism in SARS-CoV-2, and inborn errors of immunity (IEIs) in MIS-C affect the regulation of immune system complex clearances and cellular adaptations. The virus has a tropism for both vascular and respiratory cells, which further causes additional symptoms necessitating standard therapy with antithrombotic treatment. The diagnostic criteria for KD, MIS-C, and SARS-CoV-2 help differentiate each condition and optimize treatment strategies. Unfortunately, long-term outcomes in KD patients who develop MIS-C due to SARS-CoV-2 infection have been inadequately documented due to the timing of the pandemic, further displaying the need for longitudinal studies in these patients. This review underlines the differences in diagnosis and treatment of KD and MIS-C. Overall, children with KD may develop MIS-C in the setting of SARS-CoV-2 infection, but further research is needed to outline specific etiologies, prognostic factors, and diagnoses.