Kawasaki disease

By usmlevideoss

Introduction:

Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is a systemic vasculitis primarily affecting medium-sized arteries. It is the most common cause of acquired heart disease in children in developed countries. If untreated, it can lead to serious cardiovascular complications, including coronary artery aneurysms.

Etiology:

  • The exact cause of Kawasaki disease is unknown, but it is thought to involve a combination of genetic susceptibility and environmental triggers, possibly infections.
  • Evidence suggests an abnormal immune response to an unidentified pathogen in genetically predisposed individuals.

Epidemiology:

  • Age group: Primarily affects children under 5 years of age, with a peak incidence between 6 months and 2 years.
  • Gender: Boys are slightly more commonly affected than girls.
  • Ethnicity: Higher prevalence among children of Asian descent, particularly Japanese and Korean populations.
  • Incidence: More common in winter and early spring.

Pathophysiology:

  • KD involves a systemic inflammatory response that affects medium-sized arteries, particularly the coronary arteries.
  • Autoimmune activation of T cells and macrophages leads to vascular damage and endothelial dysfunction.
  • Inflammation of vessel walls (vasculitis) may cause coronary artery aneurysms, thrombosis, and ischemia.

Clinical Manifestations:

The clinical course includes three phases:

  1. Acute Phase (1-2 weeks):
    • Fever: Persistent and unresponsive to antipyretics (>5 days).
    • Conjunctivitis: Bilateral, non-exudative.
    • Mucosal changes: Strawberry tongue, cracked red lips. Erythema of oral and pharyngeal mucosa 
    • Extremity changes: Erythema and swelling of hands/feet.
    • Polymorphous rash: Non-vesicular, widespread.
    • Cervical lymphadenopathy: Usually unilateral and >1.5 cm.
  2. Subacute Phase (2-6 weeks):
    • Desquamation of fingers and toes.
    • Development of coronary artery aneurysms.
    • Thrombocytosis.
  3. Convalescent Phase (6-8 weeks):
    • Symptoms resolve, but coronary artery complications may persist.

Diagnosis:

Clinical Criteria:

Diagnosis requires fever lasting >5 days and at least 4 of the 5 principal clinical features:

  1. Bilateral conjunctival injection.
  2. Oral mucosal changes.
  3. Peripheral extremity changes.
  4. Polymorphous rash.
  5. Cervical lymphadenopathy.

Incomplete Kawasaki: Does not meet 4 out of 5 criteria

Laboratory Findings:

  • Elevated ESR and CRP.
  • Leukocytosis with neutrophilia.
  • Thrombocytosis in the subacute phase.
  • Elevated liver enzymes and hypoalbuminemia.

Imaging:

  • Echocardiography: Essential for assessing coronary artery involvement.
  • CT coronary angiography: the most sensitive test for noninvasive diagnosis of coronary complications

Treatment:

  1. Intravenous Immunoglobulin (IVIG):
    • Reduces the risk of coronary artery aneurysms when given early (within 10 days of symptom onset).
  2. Aspirin:
    • High-dose aspirin is given during the acute phase for its anti-inflammatory effects.
    • Low-dose aspirin is continued to prevent thrombosis in the subacute and convalescent phases.
  3. Corticosteroids or Biologics:
    • Considered for IVIG-resistant cases.
  4. Supportive Care:
    • Adequate hydration and monitoring for complications.

Prognosis:

  • With prompt treatment, the prognosis is excellent, and most children recover fully.
  • Without treatment, up to 25% of children may develop coronary artery aneurysms, increasing the risk of myocardial infarction or sudden death.
  • Long-term cardiac follow-up is necessary for those with coronary artery involvement.

SUPERPoint:

Kawasaki disease is a systemic vasculitis affecting medium-sized arteries, primarily in children under 5, and is characterized by persistent fever, conjunctivitis, mucocutaneous changes, rash, and lymphadenopathy. Prompt treatment with IVIG and aspirin significantly reduces the risk of coronary artery complications.

SUPERFormula:

Child < 5 years + Fever > 5 days + Conjunctivitis + Mucosal changes (e.g., strawberry tongue) + Polymorphous rash + Extremity changes + Cervical lymphadenopathy + Coronary artery aneurysm risk + Diagnosis via clinical criteria and echocardiography + Treatment with IVIG and aspirin = Kawasaki Disease.