14-49: Kawasaki Disease

Clinical Summary

Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is an acute self-limited medium- to small-vessel vasculitis of unknown etiology occurring most commonly in young children with a peak incidence between 1 and 2 years of age. The classic diagnosis is made clinically and is based on the presence of ≥ 5 days of fever and at least four of the following five principal clinical features without an alternative explanation:

1. Generalized polymorphous rash usually occurring within 5 days of the onset of fever and most commonly appearing as a nonspecific, diffuse maculopapular eruption. Early desquamation may occur in the perineal region, especially in infants.

2. Bilateral bulbar conjunctivitis sparing the limbus and most often nonexudative.

3. Changes to the lips and oral mucosa including dry, red, cracked lips, strawberry tongue, and diffuse erythema of the oropharyngeal mucosa.

4. Peripheral extremity changes: acute erythema of the palms and soles and/or swelling of the dorsal aspects of the hands and feet followed in 2 to 3 weeks by desquamation of the fingers and toes beginning in the periungual region. One to 2 months after the onset of the fever, deep transverse grooves across the nails (Beau lines) may appear.

5. Cervical lymphadenopathy that is usually unilateral, confined to the anterior cervical triangle, and with at least one node ≥ 1.5 cm in diameter.

The fever of KD is typically spiking and unremitting with peak temperatures often greater than 40°C (104°F). Incomplete (atypical) KD, which is more common in infants, does not meet all of the classic criteria but should be suspected in any child with unexplained fever for ≥ 5 days with two to three KD-associated clinical criteria or in infants (especially those ≤ 6 months of age) with ≥ 7 days of unexplained fever alone. Laboratory evaluation is necessary to support the diagnosis of incomplete KD and includes elevated ESR (≥ 40 mm/h) or CRP (≥ 3 mg/dL), and ≥ 3 supplemental laboratory criteria (albumin ≤ 3 g/dL, anemia for age, elevation of alanine aminotransferase, platelet count after 7 days ≥ 450,000/mm³, white blood cell count ≥ 15,000/mm³, and urine ≥ 10 white blood cells/high-power field). An abnormal echocardiogram may also aid in the diagnosis of incomplete KD.

Coronary artery aneurysms or ectasias are the most important complication of KD and develop in 20% to 25% of untreated children and may lead to ischemic heart disease, myocardial infarction, or sudden death. KD may also cause abdominal pain, aseptic meningitis, uveitis, myocarditis, arthritis, liver dysfunction, and gallbladder hydrops. Severe complications include macrophage activation syndrome and “Kawasaki shock syndrome” due to myocardial dysfunction. The differential diagnosis for KD includes scarlet fever, staphylococcal scalded skin syndrome, toxic ...