Table 2.

Comparisons between MIS-C and other Childhood Inflammatory Disorders with Overlapping Features^a, ^b

CSS	MIS-C (CDC)	KD (AHA)	TSS (CDC)
Age	<21	Typically <5 y	Any
	AND
Fever	>38.0°C ≥24 h	≥5d	(i) >38.9°C
	AND	AND	AND/OR (4 of 5)
Clinical features	Severe disease requiring hospitalization with multisystem (≥2) involvement (cardiac, renal, respiratory, hematological, GI, dermatological, CNS)	≥4 of following: (i) mucocutaneous signs; (ii) bilateral nonexudative conjunctival injection; (iii) rash; (iv) extremity changes; (v) cervical lymphadenopathy (≥1.5 cm). KDSS = KD + hypotension	(ii) Rash; (iii) desquamation; (iv) hypotension; (v) multisystem involvement (GI, muscular, mucous membrane including conjunctival injection, renal, hepatic, low platelets, CNS)
	AND	OR (with 2–3 clinical features)	AND
Laboratory	(i) One or more inflammatory marker (CRP, ESR, fibrinogen, procalcitonin, D-dimer, ferritin, LDH, or IL-6, elevated PMN, lymphocytopenia, hypoalbuminemia); AND (ii) SARS-CoV-2 RT-PCR, antibody, or antigen positive (or exposure within 4 weeks) AND no other microbiological diagnosis	Supportive of incomplete KD: (i) elevated CRP and/or ESR, AND (A) Three or more of: anemia, platelets ≥450 000, albumin ≤3.0, elevated ALT, WBC ≥15 000/ml, urine ≥10 WBC, OR (B) positive echocardiogram AND No other microbiological diagnosis	Negative blood or CSF culture (blood may be positive for Staphylococcus aureus) AND negative serologies for Rocky Mountain spotted fever, leptospirosis, or measles virus

^aAdvising professional/public health agency in parentheses.

^bAbbreviations: AHA, American Heart Association; ALT, alanine aminotransferase; CDC, US Center for Disease Control; CRP, C-reactive protein; CSF, cerebrospinal fluid; ESR, erythrocyte sedimentation rate; GI, gastrointestinal; LDH, lactate dehydrogenase; PMN, polymorphonuclear cell/ neutrophil; WBC, white blood cell count.