Background. New coronaviral infection (COVID-19) in most cases has less severe course in children than in adults. However, there were reports from the number of European countries and from United States (from March 2020) about children with new disease with signs of Kawasaki disease (KD) and toxic shock syndrome (TSS). So it has received one of the names children’s multisystem inflammatory syndrome (CMIS) associated with COVID-19. The aim of the study is to summarize up-to-date information about this disease.Methods. Information search in PubMed database, CDC (USA) and WHO websites, Search for information in PubMed database, on CDC (USA) and WHO websites, analysis of the medical records of observed patient with CMIS.Results. Clinical and laboratoryinstrumental manifestation and outcomes of CMIS in 120 children from Italy, France, Switzerland, England, USA with similar signs were analyzed. Proposed international diagnostic criteria of the disease in comparison with other phenotypically similar diseases (KD, shock syndrome at KD, TSS of Staphylococcal and Streptococcal etiology, macrophage activation syndrome), clinical observation of patient, algorithm of evaluation and management of patients with CMIS are presented.

Coronavirus disease 2019 (COVID-19) in children in most cases is asymptomatic or mild, and its most severe late complication is multisystem inflammatory syndrome in children (MIS-C). The aim of the study is to find clinical, laboratory and instrumental characteristics, description of therapeutic tactics, including determination of the profile of patients requiring Tocilizumab prescription and the outcomes of MIS-C associated with COVID-19. Materials and methods of research: 245 children aged 3 months – 17 years old were included in the pilot prospective multicenter open-label comparative study with MIS-C associated with COVID-19, verified based on CDC criteria (2020). Results: the median age of patients was 8 [5; 10] years, boys predominated among the patients (57.1%); MIS-C manifested itself as a combination of the symptom complex of Kawasaki disease (KD, 53.1% of patients), more often of atypical form, cardiovascular (66.1%), gastrointestinal (61.2%), neurological (27.3%) symptoms and signs of detection of the urinary (29.4%) and respiratory (19.6%) systems; macrophage activation syndrome (MAS) was diagnosed in 19.5% of patients. Therapy included glucocorticosteroids (97.6%), antibiotics (95.5%), anticoagulants (93.9%), intravenous immunoglobulin (34.7%), vasoactive/vasopressor support (31.8%), Tocilizumab (15.1%), mechanical ventilation (2.4%), extracorporeal membrane oxygenation (0.4%). Patients receiving Tocilizumab, statistically significantly more often compared with patients without this therapy, were in the intensive care unit (ICU, 86.5% versus 40.9%, p<0.001), more often required vasopressor therapy (70.3% versus 25%, p<0.001), had statistically significantly higher markers of laboratory inflammatory activity. Treatment in 47.8% of cases was carried out in an ICU; one child has died. In 4.1%, according to echocardiography, coronaritis, ectasia of the coronary arteries without the formation of persistent aneurysms were detected. Conclusion: MIS-C associated with COVID-19 has clinical signs of KD, often of the incomplete form, accompanied by arterial hypotension/shock, MAS, which requires intensive therapy, and the prescription of Tocilizumab.

Multisystem Inflammatory Syndrome in Children (MIS-C) associated with new coronavirus infection (COVID-19), with signs of Kawasaki disease (KD) and toxic shock syndrome, well-defined diagnostic criteria, is the most severe manifestation of COVID-19 in pediatric patients. MIS-C is analogous to the cytokine storm in children with COVID-19. The article presents a clinical observation of a child with MIS-C with a lethal outcome. Clinical and anamnestic data, the results of laboratory and instrumental research allowed to diagnose MIS-C in a 2-year-old girl with full KD form. Autopsy results, detailed microscopic examination, which revealed systemic vasculitis of small and mediumsized vessels, inflammatory infiltrates in different organs, are presented, clinical and morphological comparisons are made.

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