Fever is the cardinal feature of KD and tends to be of abrupt onset. The fevers are typically high, above 39°C (102.2°F), and don’t necessarily remit with antipyretics. According to the classic case definition, fever should be present for longer than four days, although the presence of at least four stigmata of KD on Day 4 of fever permits the diagnosis of KD. Those children who have fewer than four criteria but evidence of coronary artery involvement on echocardiography also meet the case definition. In Japan, children who have four or fewer days of fever but whose illness has been shortened by the administration of IVIG also meet diagnostic criteria.
There is no specific rash for KD, although it is commonly a diffuse, maculopapular rash that begins on the trunk. Desquamation in the perineal area is also common in the first week of illness. Morbilliform rashes, erythroderma and erythema multiforme have all been described in patients with KD. Bullous or vesicular rashes are not typical. Conjunctival injection without discharge that spares the limbus (the transitional zone between the cornea and the conjunctiva) is seen in greater than 90% of children with KD.
There are several findings in the oropharynx, including a strawberry tongue, a diffusely red oropharynx without ulcers or exudate, and erythematous, cracked lips.
There are two phases to the extremity changes seen in KD: With fever, children have firm swelling of the hands and feet with erythema of the palms and soles. Two to three weeks following fever onset and in the subacute period, periungual peeling, first in the hands and then the feet, appears.
The least commonly seen of the criteria is unilateral cervical chain lymph node swelling, less than 1.5 cm in diameter, which usually appears as a group of matted nodes on imaging.
The classic case criteria were developed as a means to perform surveillance of the disease in Japan, and to distinguish KD from acute rheumatic fever and Stevens-Johnson syndrome. It has become clear to clinicians that not all children with KD meet the classic clinical criteria, but some are at higher risk for coronary artery abnormalities (CAA).11 An algorithm utilizing laboratory and echocardiographic data has been developed by the AHA to assist clinicians in diagnosing children with fever of five days or longer and two or three features of KD (Figure 1).2 A retrospective study of patients with KD and coronary artery aneurysms showed that the algorithm correctly identified 97% of children with fewer than four stigmata for treatment with IVIG.12
