Kawasaki Disease: Systemic Vasculitis and Cutaneous Signs

Overview of Kawasaki Disease

Kawasaki disease is an acute, systemic vasculitis predominantly affecting infants and young children (peak incidence 2-5 years) caused by an unknown infectious agent. The disease presents with characteristic cutaneous and systemic manifestations and, critically, involves coronary artery vasculitis that can lead to coronary artery aneurysms with myocardial infarction and sudden cardiac death if untreated. Early recognition of Kawasaki disease based on its clinical features and prompt initiation of therapy dramatically reduces the risk of coronary complications. The disease is more common in Asian and Pacific Islander populations but occurs worldwide. Kawasaki disease is the leading cause of acquired heart disease in children in developed countries.

Epidemiology and Etiology

Kawasaki disease affects approximately 15-20 per 100,000 children under 5 years annually in Japan, 9-10 per 100,000 in the United States, and lower rates in other regions. The disease shows slight male predominance (1.5:1 male to female ratio). The etiology remains unknown but likely involves infection with an unknown pathogen in genetically susceptible hosts. Theories include involvement of enteroviruses, group A Streptococcus, or toxin-producing bacteria, though no single etiologic agent has been definitively identified. The disease shows seasonal variation in some geographic regions. Most cases are sporadic, though clustering in time and space has been documented.

Clinical Diagnostic Criteria

Diagnosis of Kawasaki disease is based on clinical criteria in the absence of a specific diagnostic test. The disease requires fever lasting 5 or more days (untreated) plus 4 of 5 of the following criteria: (1) polymorphous rash, (2) conjunctival injection without exudate, (3) oral changes including strawberry tongue, (4) extremity changes including erythema and edema of hands and feet, and (5) cervical lymphadenopathy. Incomplete Kawasaki disease may present with fever and fewer than 4 criteria. The diagnosis requires clinical judgment, particularly in early stages when full criterion sets have not yet developed.

Cutaneous Manifestations

The skin changes in Kawasaki disease are characteristic but nonspecific. The rash typically appears during the first 5 days of fever and is described as maculopapular, measles-like, or morbilliform. The rash predominantly affects the trunk and extremities, often sparing the face. The rash may be polymorphous with varied morphology. Erythema and edema of the hands and feet is distinctive. In the acute phase, the palms and soles show erythema with potential blistering. During convalescence (1-2 months after disease onset), characteristic peeling (desquamation) of the palms and soles from the fingertips and toe tips occurs, often in glove-like or sock-like distribution. This distinctive late desquamation pattern is highly suggestive of prior Kawasaki disease. Other features include erythema at the site of BCG vaccination if present, and in some cases, sterile pyuria and erythematous lesions mimicking keratitis.

Systemic Manifestations and Cardiac Involvement

Beyond skin changes, Kawasaki disease involves multiple organ systems. Conjunctival injection (bilateral, nonpurulent) is nearly universal. Oral changes include erythema, strawberry tongue, and lip erythema/cracking. Cervical lymphadenopathy (typically unilateral and >1.5 cm) occurs in 50-75% of cases. Cardiac involvement represents the most serious manifestation. Myocarditis develops with coronary artery vasculitis and potential coronary artery aneurysms. The coronary complications develop over the first 1-4 weeks of illness and persist chronically if not treated. Untreated Kawasaki disease results in coronary aneurysms in 25% of patients; with appropriate therapy, this decreases to <5%. Myocardial infarction can occur acutely or years later from coronary sequelae.

Diagnostic Testing and Imaging

No specific laboratory test confirms Kawasaki disease. Inflammation is typically evident (elevated ESR, CRP, platelet count). Echocardiography is essential to evaluate for coronary artery abnormalities. Initial echocardiography should be performed as soon as Kawasaki disease is suspected to establish baseline cardiac status. Follow-up echocardiography is performed at 6-8 weeks and 1 year after disease onset to detect coronary aneurysms that may develop or regress. Coronary CT angiography or cardiac catheterization may be performed in selected cases with coronary involvement.

Management and Treatment

Prompt treatment dramatically reduces coronary complications. Intravenous immunoglobulin (IVIG) 2 g/kg as a single infusion plus high-dose aspirin are standard first-line therapy. IVIG and aspirin should be started within 10 days of fever onset (ideally within 5 days) to maximize benefit. The mechanism of IVIG benefit remains unclear but is highly effective at preventing coronary aneurysms. Additional agents including corticosteroids or biologic therapies may be considered in IVIG-refractory cases. Antiplatelet therapy is continued long-term, with aspirin dosing adjusted based on coronary status. Long-term anticoagulation may be indicated for patients with coronary aneurysms.

Frequently Asked Questions

What causes Kawasaki disease? The cause remains unknown but likely involves infection with an unknown pathogen in genetically predisposed children.

Is this contagious? The contagiousness of Kawasaki disease remains unclear; current evidence suggests limited person-to-person spread.

Will my child have lasting heart disease? With prompt treatment, most children avoid coronary complications. Long-term cardiac follow-up is warranted.

Are the skin changes permanent? The rash resolves, and peeling desquamation is temporary, leaving no scars or permanent marks.

Will my child develop other episodes? Recurrence is rare (2-3% of cases), though some families report multiple affected siblings.

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