Characteristics of Multisystem Inflammatory Syndrome in Children (MIS-C) with Hyperferritinemia

Background: Multisystem inflammatory syndrome in children (MIS-C) is a serious complication of COVID-19. Ferritin levels are used to assess severity and to predict the clinical course of various systemic inflammatory diseases that can cause cytokine storm. In this study, we investigated the clinical manifestations of patients with MIS-C and compared the characteristics of MIS-C with hyperferritinemia and MIS-C without hyperferritinemia. Methods: Medical records of 22 patients hospitalized with MIS-C from January 2020 to December 2022 were retrospectively reviewed. The characteristics of the MIS-C with hyperferritinemia group (n = 11) and the MIS-C without hyperferritinemia group (n = 11) were compared. Results: All 22 patients with MIS-C had hyperinflammation, multi-organ dysfunction, and laboratory evidence of SARS-CoV-2 infection. Compared to the MIS-C without hyperferritinemia group, the MIS-C with hyperferritinemia group had more severe systemic inflammation (e.g., thrombocytopenia, hypoalbuminemia, and two or more immunomodulators) and organ dysfunction (e.g., shock, number of involved organs, and intensive care unit admission). There were no significant differences in demographics and clinical findings between the two groups. Conclusion: We found that hyperferritinemia is an important feature of severe MIS-C in terms of systemic inflammation and organ dysfunction. Subsequent studies are needed to evaluate the clinical significance of hyperferritinemia in various Kawasaki disease (KD)-like hyperinflammatory diseases, including MIS-C and severe KD.