Multisystem Inflammatory Syndrome in Children (MIS-C)

The novel coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has developed into a pandemic. A unique challenge of this pandemic has been the emergence of multisystem inflammatory syndrome in children (MIS-C), a rare post-infectious hyperinflammatory disorder associated with SARS-CoV-2. This syndrome is characterized by overwhelming systemic inflammation, fever, hypotension, and cardiac dysfunction. This disorder may also have features overlapping with Kawasaki disease (KD), macrophage activation syndrome (MAS), and toxic shock syndrome (TSS). The goal of this review is to outline the presenting features, presumed immunopathogenesis, management, and outcomes of patients with MIS-C.

Patients with MIS-C present with characteristics that fall within a wide clinical spectrum. Main features include fever, gastrointestinal symptoms such as abdominal pain and diarrhea, and cardiac complications such as myocarditis and coronary artery aneurysms, although various other features have been reported. Younger children may present with features of Kawasaki-like disease, and older children are often admitted to the intensive care unit with cardiogenic shock. Current treatment guidelines recommend intravenous immunoglobulins (IVIG) and glucocorticoids, with utilization of biologics in refractory cases. Fortunately, the majority of patients recover, with resolution of the systemic inflammation and cardiac abnormalities. Mortality from MIS-C is rare. This review provides an overview of the presenting features, proposed pathogenesis, suggested therapies, and outcomes of MIS-C. Clinicians must have a high clinical suspicion for this disorder in children who have had recent COVID-19 infection or exposure and present with a significant inflammatory response. Understanding of this disorder continues to evolve, and prompt diagnosis and treatment allow for the best possible outcome for patients with MIS-C.