Multisystem Inflammatory Syndrome in Children

Multisystem Inflammatory Syndrome in Children (MIS-C) is a rare but serious condition that typically occurs in children who have been exposed to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection. The onset of MIS-C generally occurs 3 to 8 weeks after the initial infection, regardless of the severity of the child's earlier symptoms. In the majority of cases, about 84%, SARS-CoV-2 exposure has been confirmed through serology, antigen testing. In the remaining instances, although confirmation is lacking, patients often report high-risk contact with individuals who tested positive for COVID-19. This delayed inflammatory response presents unique challenges to clinicians, requiring prompt identification and intervention to mitigate long-term effects. MIS-C shares several clinical and pathological features with other hyper-inflammatory conditions, such as Kawasaki Disease (KD) and Macrophage Activation Syndrome (MAS), which can complicate diagnosis and treatment. The pathophysiology of MIS-C is thought to be linked to an exaggerated immune response triggered by the SARS-CoV-2 infection, where the bodyâ??s immune system attacks its own tissues, leading to widespread inflammation. The key symptoms of MIS-C include fever, gastrointestinal disturbances, rash, conjunctivitis and, in some cases, cardiovascular complications such as myocarditis or shock. The variability in clinical presentation, however, complicates diagnosis. Some children may present with mild symptoms, while others may rapidly progress to severe multiorgan dysfunction. The degree of organ involvement, including the heart, kidneys and gastrointestinal system, varies from case to case, further complicating treatment strategies. Additionally, the inflammatory markers typically elevated in MIS-C-uch as C-Reactive Protein (CRP) and ferritin-overlap with other pediatric inflammatory conditions, making the clinical differentiation challenging without the proper context of recent SARS-CoV-2 exposure.

Author(s): Jorge Brozek

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