What are the diagnostic criteria and treatment for Kawasaki disease?

Kawasaki Disease Diagnostic Criteria

Classic Kawasaki disease is diagnosed by fever lasting at least 5 days plus at least 4 of 5 principal clinical features: oral mucosal changes, bilateral conjunctival injection, polymorphous rash, extremity changes, and cervical lymphadenopathy. 1

Principal Clinical Features (Must Have ≥4 of 5)

1. Oral mucosal changes: Erythema and cracking of lips, strawberry tongue, and/or erythema of oral and pharyngeal mucosa 1

2. Bilateral bulbar conjunctival injection: Nonexudative, primarily affecting the bulbar conjunctiva 1

3. Polymorphous rash: Most commonly maculopapular, diffuse erythroderma, or erythema multiforme-like 1

4. Extremity changes:

   • Acute phase: Erythema and edema of hands and feet 1
   • Subacute phase: Periungual desquamation (typically 2-3 weeks after fever onset) 1

5. Cervical lymphadenopathy: Usually unilateral, ≥1.5 cm diameter, confined to anterior cervical triangle (least common principal feature) 1

Fever Characteristics

• High-spiking fever typically exceeding 39-40°C (102.2-104°F) 1
• Remittent pattern with peaks often reaching 40°C 1
• Without treatment, persists 1-3 weeks (mean 11 days) 1
• Day of fever onset counts as day 1 1

Diagnostic Timing Modifications

The diagnosis can be made with only 4 days of fever when ≥4 principal features are present, particularly when hand and foot swelling are evident. 1 Experienced clinicians may establish diagnosis with only 3 days of fever in rare cases with classic presentations, though this requires significant clinical experience. 1

Incomplete (Atypical) Kawasaki Disease

Consider incomplete Kawasaki disease in children with fever ≥5 days AND only 2-3 principal features, or in infants with fever ≥7 days without other explanation. 2, 3

Evaluation Algorithm for Incomplete KD:

• Check inflammatory markers: ESR and CRP 2, 3
• Assess supplemental laboratory criteria 2, 3
• Obtain echocardiogram to evaluate for coronary artery abnormalities 2, 3
• If coronary artery abnormalities are detected, the diagnosis of KD is confirmed in most cases 1

Supportive Laboratory Findings

• Elevated ESR and CRP (acute phase reactants) 1
• Normal or elevated white blood cell count with neutrophil predominance 1
• Thrombocytosis (common in second week after fever onset) 1
• Low serum sodium and albumin levels 1
• Elevated serum liver enzymes 1
• Sterile pyuria 1

Additional Clinical Features (Not Required for Diagnosis)

• Musculoskeletal: Arthritis, arthralgia with pleocytosis of synovial fluid 1
• Gastrointestinal: Diarrhea, vomiting, abdominal pain, hepatitis, gallbladder hydrops 1

High-Risk Populations Requiring Heightened Suspicion

• Infants <6 months: May present with only prolonged fever and irritability, yet have the highest risk of coronary abnormalities 2, 3
• Older children and adolescents: Often have delayed diagnosis and higher prevalence of coronary artery abnormalities 2, 3

Critical Diagnostic Pitfalls

Clinical features are typically not all present simultaneously—watchful waiting and careful review of prior signs and symptoms may be necessary to establish diagnosis. 1 Some features may have resolved by the time of presentation, particularly in patients presenting after 1-2 weeks of fever. 1

Cervical lymphadenopathy as the predominant initial finding can mimic bacterial lymphadenitis, significantly delaying diagnosis—fever persists and other typical features follow. 1 Imaging (ultrasound or CT) can help differentiate: KD shows multiple enlarged nodes with retropharyngeal edema, while bacterial lymphadenitis typically shows a single node with hypoechoic core. 1

Treatment

Early treatment with IVIG and aspirin within 10 days of fever onset significantly reduces coronary artery abnormality risk. 2, 3 Fever typically resolves within 36 hours after IVIG completion; persistence indicates IVIG resistance requiring further therapy. 1, 2