What are the diagnostic criteria and treatment for Kawasaki disease?

Kawasaki Disease: Signs and Symptoms

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

Diagnostic Criteria

Fever Characteristics

• High-spiking fever typically exceeding 39-40°C (102.2-104°F) 1
• Must persist for at least 5 days (day of onset = day 1) 1
• Without treatment, fever continues 1-3 weeks on average 1
• Diagnosis can be made with only 4 days of fever when ≥4 principal features are present, particularly with hand/foot swelling 1
• Experienced clinicians may diagnose with 3 days of fever in rare classic presentations 1

The Five Principal Clinical Features

1. Oral Mucosal Changes 1

• Erythema and cracking of lips
• Strawberry tongue
• Erythema of oral and pharyngeal mucosa

2. Bilateral Conjunctival Injection 1

• Nonexudative (no discharge) 1
• Primarily bulbar conjunctiva with limbal sparing 1
• Begins shortly after fever onset 1
• Anterior uveitis often detected on slit-lamp examination 1
• Exudative conjunctivitis, photophobia, or eye pain should prompt alternative diagnosis 1

3. Polymorphous Rash 1

• Most commonly diffuse maculopapular eruption 1
• Scarlatiniform erythroderma or erythema multiforme-like patterns also common 1
• Extensive involvement of trunk and extremities 1
• Characteristic accentuation in groin with early desquamation 1
• Appears within 5 days of fever onset 1
• Bullous, vesicular, or petechial rashes are NOT consistent with KD and require alternative diagnosis 1

4. Extremity Changes 1

• Acute phase: Erythema of palms and soles with firm, sometimes painful induration of hands/feet 1
• Subacute phase (2-3 weeks): Periungual desquamation extending to palms and soles 1
• Late finding (1-2 months): Beau's lines (transverse nail grooves) 1

5. Cervical Lymphadenopathy 1

• Least common principal feature 1
• Usually unilateral, ≥1.5 cm diameter 1
• Confined to anterior cervical triangle 1
• Multiple enlarged nodes with retropharyngeal edema or non-suppurative phlegmon 1

Critical Diagnostic Pitfalls

Timing and Sequential Presentation

• Clinical features are typically NOT all present simultaneously 1
• Careful history may reveal features that resolved before presentation 1
• Some features may have abated in patients presenting after 1-2 weeks of fever 1

High-Risk Populations Often Missed

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

Mimicking Bacterial Lymphadenitis

• Cervical lymphadenopathy may be the most prominent initial finding, delaying diagnosis 1
• Ultrasound/CT helpful: KD shows multiple nodes with retropharyngeal edema; bacterial shows single node with hypoechoic core 1

Incomplete (Atypical) Kawasaki Disease

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

Evaluation Algorithm for Incomplete KD

• Check inflammatory markers (ESR, CRP) 1, 2
• Assess supplemental laboratory criteria 2
• Obtain echocardiogram if inflammatory markers elevated 2
• Diagnosis confirmed if coronary artery abnormalities detected with only 3 clinical features 1, 2

Supportive Laboratory and Clinical Findings

Laboratory Abnormalities 1, 2

• Elevated ESR and CRP
• Normal or elevated WBC with neutrophil predominance
• Low serum sodium and albumin
• Elevated liver enzymes
• Sterile pyuria
• Thrombocytosis common in second week after fever onset 1

Additional Clinical Features 1

• Musculoskeletal: Arthritis, arthralgia (approximately one-third of patients in acute phase) 1, 3
• Gastrointestinal: Diarrhea, vomiting, abdominal pain, hepatitis, gallbladder hydrops 1, 2
• Cardiovascular: Gallop rhythm, ECG changes 2

Key Differential Diagnoses to Exclude

Features that should prompt alternative diagnosis: 1

• Exudative conjunctivitis or pharyngitis
• Oral ulcerations
• Splenomegaly
• Vesiculobullous or petechial rashes

Consider these alternatives: 2

• Viral infections (measles, adenovirus)
• Bacterial infections (scarlet fever, staphylococcal scalded skin syndrome)
• Measles shares many features with KD—consider in unimmunized children 1

Treatment Implications

Fever typically resolves within 36 hours after IVIG completion; persistence indicates IVIG resistance requiring further therapy 1

Early treatment with IVIG and aspirin within 10 days of fever onset significantly reduces coronary artery abnormality risk 2