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23

Conferences and Reviews
Kawasaki Disease
The Mystery Continues
DAVID J. BRADLEY, MD, and MARY P. GLODE, MD, Denver, Colorado

Kawasaki disease is an acute systemic vasculitis of unknown cause first described in Japan in 1967. It affects children younger than 10 years, predominantly those younger than 3 years. Children of Asian ancestry are more commonly affected than white children.The diagnosis is made when 4 of the following 5 signs or symptoms are present with fever for at least 5 days: polymorphous rash; conjunctival injection; oral mucosal changes; cervical lymphadenitis; and erythema, swelling, or desquamation of the hands and feet. Various symptoms may be seen also, among them pronounced irritability, arthralgia, and abdominal pain. No diagnostic test exists, andclinicians must carefully exclude diseases that mimic Kawasaki disease. In addition to the above clinical findings, Kawasaki disease causes aneurysm formation in medium-sized arteries, particularly the coronary arteries. Found in about a fourth of patients, these lesions may persist, scar with stenosis, or resolve angiographically. The treatment consists of administering high-dose aspirin andintravenous immune globulin, with the goal of relieving acute illness and minimizing sequelae. Although most respond rapidly, almost 10% of children do not improve clinically with treatment. Complications of Kawasaki disease include myocardial infarction, which may occur during acute illness or later, as a result of coronary abnormalities. (Bradley DJ, Glode MP. Kawasaki disease: the mystery continues. WestJ Med 1998; 168:23-29)
Since it was first described by the pediatrician Tomisaku Kawasaki almost 30 years ago, the disease that bears his name has been a puzzle for all who have seen and treated it. A multisystem vasculitis of children, Kawasaki disease (also known as Kawasaki syndrome, or mucocutaneous lymph node syndrome) can now be treated effectively in most cases, but its pathogenesisremains unknown. At its worst, it is a condition that damages coronary arteries and may result in fatal myocardial infarction; at its most innocuous, it is an illness of curious mucocutaneous findings and "fever of unknown origin." Because of its potential to cause severe illness, however, physicians who care for children must be able to identify it definitively and treat it promptly. In 1961, DrKawasaki saw his first patient with high fevers, cervical lymphadenopathy, conjunctival and oral mucosal changes, and acral edema. He recounts, "The patient had what we now call typical Kawasaki disease, but looking at him from the perspective of that time, I could not form any clear idea of the disease process involved."' Over several years he observed similar cases, sometimes diagnosed by others as"StevensJohnson syndrome complicated by carditis." He compiled these in a published series of 50 children in 1967.2

Initial skepticism regarding the new diagnosis gave way
to widespread acceptance with confirmatory reports

elsewhere, including an independent discovery of the disease by an American group in the early 1970s.3
Epidemiology It is fitting that Kawasaki disease was described by aJapanese physician; the average annual incidence in Japan is nearly 100 per 100,000 children younger than 5 years, higher than any other major population studied.4 In North American populations, the incidence for all races combined is about 10 per 100,000 children younger than 5. Asian Americans are at least three times more likely and black Americans two times more likely than whites to bediagnosed with the disease.6 Patients with Kawasaki disease are almost always younger than 10 years. The peak incidence is at about 1 year of age and falls off sharply for younger and older age groups. The disease is 1.5 to 2 times more common, and almost 5 times more likely to be fatal, in boys than in girls. Death from Kawasaki disease is a relatively rare event, occurring in less than 0.5% of...