Kawasaki disease is an acute vasculitis of unknown etiology that primarily affects children younger than 5 years, although it can affect older children. Cardiac complications are the major cause of morbidity and mortality in Kawasaki disease and can include myocarditis. Long-term sequelae include coronary artery dilation. Treatment is high-dose intravenous immunoglobulin and aspirin. Multisystem inflammatory syndrome in children (MIS-C) is a severe hyperinflammatory syndrome associated with COVID-19 disease. It shares clinical characteristics with Kawasaki disease but causes hyperinflammation and often results in cardiac dysfunction. Treatment for MIS-C is intravenous immunoglobulin and glucocorticoids. Myocarditis is inflammation of the myocardium and pericardium and has multiple causes. It is associated with COVID-19 infection and mRNA COVID-19 vaccines. The incidence and clinical significance of these associations remain uncertain and are a current topic of research and debate.

Case 4. AT is a 4-year-old patient of Japanese descent who is brought to your office by his parents after 5 days of fever. On examination, he has conjunctival injection; red, cracked lips and strawberry tongue; swollen and erythematous hands and feet; and cervical lymphadenopathy. You suspect he has Kawasaki disease or multisystem inflammatory syndrome in children (MIS-C).

Kawasaki Disease

Kawasaki disease is an acute vasculitis that occurs in children.¹ It presents as a self-limited febrile disease that leads to cardiac artery aneurysms in up to 25% of untreated children. Kawasaki disease primarily affects children younger than 5 years with an annual incidence in the United States of approximately 25 out of 100,000 children in that age range.² It is approximately 10 times more common in Japan (243-266 per 100,000 children younger than 5 years).¹ In the United States it is more common among children of Asian, specifically Japanese, and Pacific Island heritage.^1,3 It is 50% more common in males than females (1.5:1 ratio) and occurs more often in winter and early spring in North America.¹