Rebound multi-system inflammatory syndrome in children (MIS-C): A case report of an extremely rare phenomenon

Abstract Background: Multi-system inflammatory syndrome in children (MIS-C) is a newly defined clinical syndrome characterized by systemic inflammation, fever, and multi-organ dysfunction related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. While MIS-C is familiar to most physicians, recurrent and rebound cases of MIS-C are extremely rare, with only two such cases reported to date. Case presentation: Here, we report the case of a five-month-old boy diagnosed with rebound MIS-C (19 days apart), with the second episode being more severe and featuring a right coronary artery aneurysm. The immunodeficiency workup returned normal. Standard MIS-C treatment protocols were followed in both episodes, eventually yielding an excellent outcome. The patient remained well within 12 months of follow-up. Conclusions: We conclude that longer and closer follow-ups of MIS-C patients may be needed, perhaps with a more aggressive treatment protocol to prevent a rebound or recurrence of the disease, though further studies are required to guide clinical decision-making.