What are the diagnostic criteria and treatment for Kawasaki disease?

Diagnosing Kawasaki Disease

Kawasaki disease is diagnosed clinically based on fever lasting at least 5 days plus the presence of at least 4 of 5 principal clinical features, or fewer features with coronary artery abnormalities detected by echocardiography. 1

Principal Diagnostic Criteria

• Fever persisting for at least 5 days (although diagnosis can be made earlier in the presence of classic features) 1
• Plus at least 4 of these 5 principal clinical features:
  • Changes in extremities:
    • Acute phase: Erythema and edema of hands and feet 1
    • Convalescent phase: Periungual desquamation of fingers and toes (typically begins 2-3 weeks after fever onset) 1
  • Polymorphous exanthema (non-specific, diffuse maculopapular eruption) 1
  • Bilateral bulbar conjunctival injection without exudate 1
  • Changes in lips and oral cavity: Erythema and cracking of lips, strawberry tongue, diffuse injection of oral and pharyngeal mucosae 1
  • Cervical lymphadenopathy (≥1.5 cm diameter), usually unilateral 1

Incomplete Kawasaki Disease

• Consider in children with:
  • Fever ≥5 days AND 2-3 principal clinical features 1
  • OR infants with fever ≥7 days without other explanation 1
• Evaluation algorithm for incomplete KD: 1
  • Check inflammatory markers: CRP and ESR
  • If CRP ≥3.0 mg/dL and/or ESR ≥40 mm/hr, assess for supplemental laboratory criteria:
    • Anemia for age
    • Platelet count ≥450,000 after 7th day of fever
    • Albumin <3.0 g/dL
    • Elevated ALT level
    • WBC count ≥15,000/mm³
    • Urine ≥10 WBC/hpf
  • If ≥3 supplemental laboratory criteria are present, obtain echocardiogram
  • Echocardiogram is positive if any of these are present:
    • Z score of LAD or RCA ≥2.5
    • Coronary artery aneurysm
    • ≥3 other features (decreased LV function, mitral regurgitation, pericardial effusion, or Z scores in LAD or RCA of 2-2.5) 1

Other Supportive Clinical and Laboratory Findings

• Cardiovascular: Gallop rhythm, distant heart sounds, ECG changes, cardiomegaly on chest x-ray, pericardial effusion 1
• Gastrointestinal: Diarrhea, vomiting, abdominal pain, hydrops of gallbladder, mild jaundice, elevated transaminases 1
• Blood: Elevated ESR, leukocytosis with left shift, positive CRP, hypoalbuminemia, mild anemia in acute phase, thrombocytosis in subacute phase 1
• Urine: Sterile pyuria of urethral origin 1
• Neurological: Extreme irritability, aseptic meningitis, rarely facial palsy 1
• Musculoskeletal: Arthralgia and arthritis, typically affecting multiple joints 1

Common Diagnostic Pitfalls

• Infants <6 months: May present with only prolonged fever and irritability, yet have high risk of coronary abnormalities 1
• Older children/adolescents: Often have delayed diagnosis and higher prevalence of coronary artery abnormalities 1
• Misdiagnosis scenarios: 1
  • Fever and pyuria misdiagnosed as urinary tract infection
  • Irritability and CSF pleocytosis misdiagnosed as aseptic meningitis
  • Cervical lymphadenitis misdiagnosed as bacterial adenitis
  • Gastrointestinal symptoms leading to surgical consultation, missing other KD features

Differential Diagnosis

• Viral infections (measles, adenovirus, enterovirus, EBV) 1
• Scarlet fever 1
• Staphylococcal scalded skin syndrome 1
• Toxic shock syndrome 1
• Bacterial cervical lymphadenitis 1
• Drug hypersensitivity reactions 1

Key Points for Accurate Diagnosis

• No specific diagnostic test exists for Kawasaki disease 1
• Echocardiography is crucial for evaluation of suspected incomplete KD 1
• Early diagnosis and treatment with IVIG and aspirin within 10 days of fever onset significantly reduces risk of coronary artery abnormalities 1, 2
• Consider KD in any child with unexplained persistent fever, even if all classic criteria are not present 1
• Maintain high index of suspicion in infants and older children/adolescents 1