A set of guidelines proposed by Western New York recommends also evaluating children with clinical features that overlap with the MIS-C case definition, but who have been screened with mild illness and laboratory abnormalities, and who do not have an alternative diagnosis. Differential diagnosis
It is essential to exclude alternative non-infectious and infectious causes of the inflammatory condition, including bacterial sepsis, staphylococcal and streptococcal shock, and infections associated with myocarditis, such as enterovirus. (Coinfection with additional pathogens, including human metapneumovirus and various other microbes, may sometimes occur.) Other potentially unrelated sources of abdominal pain include appendicitis and mesenteric adenitis.Differential diagnosis with Kawasaki disease can be challenging, given the lack of a diagnostic test for either condition. It is not currently known whether the newly described condition is superimposable with Kawasaki disease shock syndrome. Since prompt diagnosis and timely treatment of actual Kawasaki disease is important to prevent complications, a call has been made to "Keep a high suspicion for Kawasaki disease in all children with prolonged fever, but especially in those younger than 1 year of age." Treatment
Due to the limited information available on this rare new diagnosis, clinical management has been largely based on expert opinion, including knowledge acquired from treating Kawasaki disease and other systemic inflammatory disorders of childhood, in addition to experience with COVID-19 in adults. Treatment is tailored for each individual child, with input from the various consulting specialists. Approaches vary.
The European Centre for Disease Prevention and Control (ECDC) has rated risk to children in Europe as being low overall, based on a very low likelihood of a child developing this high impact disease. Regarding ethnicity, the condition seems to affect more children of African, Afro-Caribbean, and Hispanic descent, whereas Kawasaki disease affects more of East Asian ancestry. Initial reports regarded children in various parts of Europe and the United States, and it was unclear to what extent the condition had gone unrecognized elsewhere. Reports have since emerged of cases in various other countries around the world. In adults, a similar condition has occasionally been reported, which has been called multisystem inflammatory syndrome in adults (MIS-A). Name
The disorder has been called by various names, including:

Multisystem inflammatory syndrome in children (MIS-C)
Multisystem inflammatory syndrome (MIS) in children and adolescents temporally related to COVID-19
Paediatric inflammatory multisystem syndrome (PIMS)
Paediatric inflammatory multisystem syndrome, temporally associated with SARS-CoV-2 infection (PIMS-TS)
Paediatric multisystem inflammatory syndrome (PMIS)
Kawa-COVID-19
Systemic inflammatory syndrome in COVID-19 (SISCoV)

Background
Symptomatic cases of COVID-19 in children have been relatively uncommon, possibly because they generally experience milder disease. Early infection tends to be associated with mild or no symptoms, while the later pulmonary phase, which can be life-threatening in adults, is usually mild or absent. While cases of children with severe symptoms are exceptional, they can occasionally require intensive care.