Chapter 47 Kawasaki Disease
PATHOPHYSIOLOGY
Kawasaki disease is an acute, self-limited vasculitic syndrome affecting infants and young children. Kawasaki disease is distinguished by marked immune system activation that contributes to the injury of small- and medium-sized blood vessels, with a predilection for the coronary arteries. Also known as mucocutaneous lymph node syndrome, Kawasaki disease affects multiple body systems and can have life-threatening cardiovascular consequences, including thrombosis of coronary arteries, coronary artery aneurysms, and coronary stenosis. Researchers speculate that Kawasaki disease has an infectious cause; however, the specific etiology remains unknown. The disease occurs in three phases; acute febrile, subacute, and late or convalescent. Diagnosis, which is sometimes confusing, has been based on strict adherence to clinical criteria. However, a substantial subset of children present with illnesses that do not completely fulfill the diagnostic criteria and are associated with the coronary diseases similar to that of the typical Kawasaki disease. These cases are labeled “atypical Kawasaki disease.” Initial treatment focuses on reducing the vascular inflammatory process. With early recognition and treatment, prognosis is excellent. The long-term prognosis for children with coronary artery abnormalities who survive the disease is unknown, but recent surveys suggest that the sequelae of Kawasaki disease are likely important causes of ischemic heart disease in young adults.
INCIDENCE
1. Of all children with diagnosed Kawasaki disease, 80% are 5 years of age or younger, with toddlers most commonly affected (50% are younger than 2 years of age).
2. In the United States the peak age for being diagnosed with Kawasaki disease is 18 months.
3. Adults, adolescents, and children less than 6 months of age are rarely affected.
4. Outbreaks of Kawasaki disease are more common in the late winter and early spring but can be seen at any time during the year.
5. Annual incidence in the United States is 5.6 per 100,000 individuals as compared to 67 per 100,000 individuals in Japan.
6. The incidence is higher in boys than in girls (1.5:1). Boys have a higher ratio of fatalities due to Kawasaki disease.
7. The disease occurs in all races but has a higher predilection for Japanese children, followed by Asian and Pacific Islanders, African Americans, Hispanics and, finally, is at its lowest incidence in whites.
8. Kawasaki disease occurs more often in twins and siblings than in the general population.
9. No evidence exists to suggest that Kawasaki disease is spread by person-to-person contact.
10. The increased rates of occurrence in family members suggest there may be a genetic predisposition to Kawasaki disease.
11. Of untreated children with Kawasaki disease, 15% to 20% develop coronary artery aneurysms.
12. Of those children treated with intravenous gamma globulin (IVIG) in the acute phase of the disease, fewer than 5% develop coronary artery abnormalities.
CLINICAL MANIFESTATIONS
Acute Febrile Phase (0 to 19 Days)
For Kawasaki disease to be diagnosed, the child must have a fever for 5 days and four of the following acute phase criteria:
1. Fever is abrupt in onset, typically high (39° to 40° C), spiking, and remittent. If left untreated, the fever may persist for 11 days on the average. The fever is present in 95% of children with Kawasaki disease.
2. Bulbar conjunctivitis is seen in the first few days of the illness, occurring shortly after the first fever. It is usually painless and not associated with exudate or edema.
3. Oropharyngeal manifestations include changes in the mouth and lips including erythema, dryness, fissuring, peeling, cracking, and bleeding of the lips; a “strawberry tongue”; and diffuse erythema of the oropharyngeal mucosa (nonexudative and nonulcerative).
4. Extremity changes include swelling and induration of the hands and feet, erythema of the palms and soles, and painful extremities; often, children no longer bear weight. The skin becomes shiny and stretched in appearance.
5. Erythematous body rash usually appears within 5 days of fever and may take many forms. Most commonly the rash is a nonspecific, diffuse, maculopapular eruption. The rash is most extensive to the trunk but can involve the face and extremities. The rash in the perineal area is accentuated, and early desquamation may occur.
6. Cervical lymphadenopathy is the least common of the criteria; it is usually unilateral and located in the anterior cervical triangle. The enlarged node is usually greater than 1.5 cm in diameter, nonfluctuant, and nontender.
7. Cardiac abnormalities include myocarditis, arrhythmias, hyperdynamic precordium, tachycardia, gallop rhythm, depressed myocardial contractility, mitral regurgitation, and coronary artery abnormalities.
Subacute Phase (12 to 25 Days)
1. Arthritis frequently includes multiple joints, most commonly large weight-bearing joints
3. Thick desquamation of the extremities, starting at the tip of the digits and progressing proximally
4. Panvasculitis of coronary arteries and formation of aneurysms; inflammation and thrombosis may lead to stenosis or obstruction
Convalescent Phase (6 to 8 Weeks)
1. Subsidence of the signs of illness
2. Appearance of deep linear transverse grooves across the fingernails and toenails (Beau’s lines), which may progress to complete shedding of the nails
3. Abnormal laboratory values begin returning to normal
4. Normalization of personality, irritability, appetite, and energy level
COMPLICATIONS
LABORATORY AND DIAGNOSTIC TESTS
Refer to Appendix D for normal values and/or ranges of laboratory and diagnostic tests.
There are no specific diagnostic tests for Kawasaki disease; however, several abnormalities have been identified.
1. Electrocardiogram (ECG)—to assess electrical conduction of the myocardium
