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
Cervical lymphadenopathy (greater than 1.5 cm diameter)
Common pitfalls may include diagnosing an infection in an infant with fever and an enlarged cervical lymph node (bacterial lymphadenitis) or sterile pyuria (partially treated urinary tract infection). The subsequent exanthem and mucosal changes may be misdiagnosed as a drug reaction to the prescribed antibiotics.
Viral meningitis may be misdiagnosed in an infant with fever, rash, and cerebrospinal fluid pleocytosis.