Kawasaki disease (KD), or mucocutaneous lymph node syndrome, is an idiopathic, multisystem vasculitis characterized by fever and mucocutaneous inflammation. It has a peak incidence in infants aged 9-11 months and is extremely rare in infants younger than 3 months. Most cases occur in individuals who live in East Asia or are of Asian ancestry / descent. Although usually self-limited, potentially life-threatening coronary artery aneurysms may develop in 20%-25% of children without treatment (versus less than 5% with appropriate therapy). Mortality most often occurs within the first weeks to a year after KD due to ischemic heart disease caused by myointimal proliferation within persistent aneurysms. Infants younger than 6 months may be at increased risk for aneurysms.

The classic case definition of KD is fever lasting at least 4 days plus the presence of at least 4 of the following principal clinical criteria:

• Bilateral bulbar conjunctival injection without exudate
• Oral mucosa changes: cracked lips, "strawberry tongue," or diffuse erythema of the mucosae
• Changes in the extremities: erythema, induration, or periungual peeling
• Polymorphous eruption
• Unilateral lymphadenopathy that is usually cervical (greater than 1.5 cm diameter)

Incomplete KD may be diagnosed with fever lasting at least 4 days plus 2 or 3 of the above 5 criteria

OR

Unexplained fever lasting more than 6 days, C-reactive protein (CRP) higher than 3 mg/dL, and/or ESR higher than 40 mm/hour and ECHO findings:

• Echocardiogram Z-score of left anterior descending (LAD) coronary artery disease (CAD) score or right coronary artery (RCA) ≥ 2.5

OR

Unexplained fever lasting more than 6 days, CRP higher than 3 mg/dL, and/or ESR higher than 40 mm/hour and 3 or more of the following:

• Anemia for age
• Thrombocytosis ≥ 450 000 platelets
• Albumen ≤ 3 g/dL
• Elevated alanine transaminase
• WBC ≥ 15 000
• Sterile pyuria (≥ 10 WBC per high-power field)