Kawasaki Disease

Notes

Medium-vessel Vasculitis | Paediatric Rheumatology | Paediatrics | Rheumatology | Vasculitides

Overview

Kawasaki disease is an acute systemic vasculitis affecting small and medium-sized vessels predominantly affecting children under 5 years old. It is the leading cause of acquired heart disease in children in developed countries. Kawasaki is often self-limiting, but 20–25% risk of coronary artery aneurysms if untreated ¹.

Definition

Vasculitis: Inflammation of blood vessel walls, which can lead to vessel wall damage, narrowing, aneurysm formation, or occlusion. In Kawasaki disease, vasculitis predominantly affects medium-sized arteries, especially the coronary arteries.
Coronary artery aneurysm: Localised dilation of a section of a coronary artery wall. A feared complication of Kawasaki disease due to inflammation weakening the arterial wall. Can lead to thrombosis, rupture, or myocardial infarction in severe cases.
Strawberry tongue: A clinical finding of erythematous, swollen tongue with prominent papillae — a hallmark of mucocutaneous involvement in Kawasaki disease and scarlet fever.

A febrile child with cracked lips, red eyes, and swollen hands may not have an infection — think Kawasaki, not just a viral illness.

Anatomy & Physiology

Affects medium-sized muscular arteries, especially coronary arteries. Inflammation involves intima, media, and adventitia of vessels.

Aetiology & Risk Factors

Unknown cause; likely infectious trigger in genetically susceptible host.
Suggested triggers: viral infections (e.g. coronavirus, adenovirus), bacterial toxins.
Risk factors
- Age < 5 years
- Asian descent, especially Japanese (2)
- Male gender
- Family history of KD

Pathophysiology

Trigger (e.g., infection) → activates innate immune response
Cytokine release (e.g. IL-1, IL-6, TNF-α) → systemic inflammation and endothelial injury
Inflammatory cells infiltrate vascular walls → necrotising arteritis
Medium-sized arteries (notably coronary) are weakened → aneurysm formation
Resolution may occur, or in severe cases → thrombosis or myocardial infarction

Clinical Manifestations

Classic (complete) KD:

High grade fever with 4 of the following:
- Conjuctivitis (bilateral non purulent)
- Rash
  - Polymorphous
  - Maculopapular
- Erythema and oedema of hands or feet
- Adenopathy (cervical lymphadenopathy)
- Mucous membranes
  - Dry cracked lips
  - Red tongue
  - Strawberry tongue
Other findings: Irritability, arthritis, aseptic meningitis, sterile pyuria
Cardiac: Coronary artery aneurysms (days 7–10), myocarditis, pericardial effusion

Fevers + CREAM

Children <6 months are at higher risk of incomplete KD and coronary aneurysms — maintain high suspicion (4).

Diagnosis

Clinical diagnosis; no single definitive test.
High grade fever ≥ 5 days (essential) plus ≥4 of 5 principal features:

Conjunctivitis (bilateral, non-exudative)
Rash (polymorphous, usually trunk/extremities)
Oral mucosal changes (cracked lips, strawberry tongue, red oropharynx)
Extremity changes (erythema, oedema, desquamation)
Cervical lymphadenopathy (usually unilateral, >1.5 cm)

Investigations:

↑ ESR and CRP (often markedly elevated)
↑ Platelets (especially after day 7), ↑ WBCs, normocytic anemia
↑ ALT/AST, hypoalbuminemia
Sterile pyuria
Echocardiogram: baseline and repeat at 2 and 6 weeks to assess coronary arteries
ECG to detect arrhythmias

Differential diagnosis:

Scarlet fever (Group A Strep)
Measles
Stevens-Johnson syndrome
Toxic shock syndrome
Systemic JIA (especially in incomplete KD)

Classification

Classic KD: Fever ≥5 days + ≥4/5 clinical features.
Incomplete KD: <4 features but compatible lab and echo findings.
Atypical KD: Unusual presentations (e.g., renal failure, hepatitis, CNS involvement).

Treatment

IVIG 2 g/kg over 10–12 hours — within first 10 days of illness (3)
Aspirin: high-dose during acute phase → low-dose until inflammation resolves or longer if coronary changes persist
Corticosteroids or infliximab in IVIG-resistant cases
Close cardiology follow-up for coronary monitoring

Treat within the first 10 days to reduce coronary artery aneurysm risk.

Aspirin is not usually used for children because of the risk of Reye Syndrome (Encephalopathy + liver damage). Kawasaki is an exception.

Complications and Prognosis

Complication

Cardiac:
- Coronary artery aneurysms (seen in ~25% if untreated, ~5% with IVIG)
- Myocarditis, pericarditis, arrhythmia
Thrombosis and MI from aneurysms
Recurrent KD (~3%)
Long-term risk of atherosclerosis

Prognosis

Excellent if treated early with IVIG.
Coronary aneurysm regression possible, especially if small.
Long-term cardiac surveillance may be needed.

Coronary aneurysm is the most important complication to remember in Kawasaki Disease.

References

McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: A scientific statement. Circulation. 2017;135(17):e927–e999.
Kato H, Sugimura T, Akagi T, et al. Long-term consequences of Kawasaki disease. A 10- to 21-year follow-up study. Circulation. 1996;94(6):1379–1385.
Newburger JW, Takahashi M, Gerber MA, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: A statement for health professionals. Pediatrics. 2004;114(6):1708–1733.
Singh S, Agarwal S, Bhattad S, et al. Management of Kawasaki disease. Indian J Pediatr. 2016;83(1):77–84.