Table 1. MIS-C definition by WHO and clinical manifestation of our patient

MIS-C definition [6]	Case 1	Case 2
Children 0–19 years of ageFever > 3 days	F/ 9 yearsFever for 7 days	F/8 yearsFever for 5 days
AND two of the following:1. Rash or conjunctivitis or mucocutaneous inflammation signs2. Shock or hypotension3. Features of myocardial dysfunction, valvulitis, pericarditis, and coronary abnormalities (elevated Troponin/NT-proBNP or ECHO findings)4. Evidence of coagulopathy (by PT, PTT, d-Dimers)5. Acute gastrointestinal problems (diarrhea, vomiting, abdominal pain)	1. Truncal rash, conjunctivitis, hand/feet swelling3. NT-proBNP ↑, LV function↓ (EF 43%)4. PT prolongation5. Abdominal pain, vomiting	3. LV function↓ (EF 43%) troponin/NT-proBNP ↑
AND elevated markers of inflammation (ESR, CRP, procalcitonin)	CRP 46.6 mg/L procalcitonin 0.52 ng/mL	(–)
ANDNo other obvious microbial cause of inflammation	Mycoplasma Ab (+)Rhinovirus (+)Metapneumovirus (+)	(–)
AND evidence of COVID-19 (antigen test, serology or RT-PCR +) or contact with patients with COVID-19.	SARS-CoV-2 Ab (+)	RT-PCR (+)SARS-CoV-2 Ab (+)
Shares common features with other pediatric inflammatory conditions including: KD, TSS, bacterial sepsis, MAS	Kawasaki disease	Kawasaki disease
Diagnosis	MIS-C	MIS-C,Infective endocarditisInfective myocarditis
Management	1. IVIG 60 g IVF (5/14)2. Aspirin 80 mg QD (5/15-)3. IV methylprednisolone 20 mg q12 hr (5/16–5/19)	1. Antiviral, Antibiotics2. Methyprednosolone3. IVIG4. Aspirin, Heparin, warfarin5. ACE inhibitor, beta-blocker6. Iron replacement

MIS-C: multisystem inflammatory syndrome in children, WHO: World Health Organization; IVIG: intravenous immunoglobulin, IVF: intravenous fluid, KD: Kawasaki disease, TSS: toxic shock syndrome, MAS: macrophage activation syndrome, CRP: C-reactive protein, ESR: erythrocyte sedimentation rate, PT: prothrombin time, aPTT: activated partial thromboplastin time, EF: ejection fraction, ECHO: echocardiography, NT-proBNP: N-terminal pro-B-type natriuretic peptide, SARS-CoV-2: severe acute respiratory syndrome coronavirus 2, COVID-19: coronavirus disease 2019, RT-PCR: reverse transcription polymerase chain reaction, Ab: antibody, (–): absent or not available, (+): positive; QD: quaque die; ACE; angiotensin-converting enzyme.