Multisystem Inflammatory Syndrome in Children Associated with COVID-19: An Interim Review

ABSTRACT

The pediatric population is relatively less affected by novel coronavirus disease 2019 (COVID-19) compared with adults, both in numbers and severity. However, evolution of a new entity, named multisystem inflammatory syndrome in children (MIS-C), has led to significant number of children being admitted to hospital, especially to intensive care units. Case definitions of MIS-C have been defined by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) separately. Autoantibodies and antibody-dependent enhancement (ADE) are the key factors proposed in pathogenesis, leading to immune dysregulation, and cytokine storm. Three distinct clinical types are observed as follows (1) fever and elevated inflammatory markers with no end-organ damage;(2) shock with severe myocardial dysfunction similar to toxic shock syndrome (155);and (3) with mucocutaneous features like Kawasaki's disease (KD). Cardiovascular and gastrointestinal symptoms are the predominant presentations. Inflammatory markers like C-reactive protein (CRP), ferritin, and interleukin (IL)-6 are raised along with high D-dimer and lactate dehydrogenase (LDH). Echocardiography may demonstrate low left ventricular ejection fraction (<50%) and/or coronary aneurysms. Reverse-transcription polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is usually negative, with most having antibodies against the virus. KD, KD shock syndrome (KDSS), and toxic shock syndrome (TSS) are the important differential diagnoses to be considered. Immunomodulatory therapy is the cornerstone of the management. Intravenous immunoglobulin (IVIg) is preferred, the next option being steroids. Supportive care, antiplatelet, and anticoagulation medications, when indicated, are also vital aspects of treatment plan. The prognosis is favorable with low mortality but meticulous cardiac monitoring and follow-up by a multidisciplinary team is very important. Being an evolving disease, future research may reveal different manifestations, newer diagnostic modalities, and better treatment options.