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 of age. Most cases occur in individuals who live in East Asia or are of Asian ancestry. 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 of age may be at increased risk for aneurysms.

The classic case definition of KD is fever lasting at least 5 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
• Exanthem
• Cervical lymphadenopathy (greater than 1.5 cm diameter)

A multisystem inflammatory syndrome potentially linked to COVID-19 has been reported in children and young adults; clinical features include Kawasaki-like and toxic shock syndrome-like presentations.