Background: Kawasaki disease (KD) is an acute vasculitis in children. Eosinophilia, a reflection of the host's immune response that can cause tissue damage, has been associated with KD, with eosinophils preferentially accumulating in the microvasculature. In early-stage Kawasaki disease (KD), lesions (perivasculitis and vasculitis) first form in the microvessels, which can then extend to the larger vessels and result in coronary artery aneurysms, possibly leading to myocardial infarction even in young children. Overall, the prevalence of coronary artery aneurysms in children with Kawasaki disease is about 10-18%, which is much higher among those not treated early in the course of the illness.  We performed this study to gain a better understanding of the initial pathogenesis of KD and to assess the relationship between eosinophilia and coronary artery disease.

Methods:  The data from forty-eight patients at Vali-asr Hospital of the Tehran University of Medical Sciences (1996-2006) were included in this cross-sectional descriptive analysis. The presence and degree of coronary artery disease was assessed by echocardiography. Data was analyzed via Fisher's exact test and student's t-test using SPSS software, v. 11.5.

Results: Eosinophilia was seen in 10 cases (22%) and cardiac lesions were observed in 19 cases (41%). The frequency of microvessel lesions was significantly lower in patients with eosinophilia (10% with eosinophilia versus 50% without eosinophilia, p<0.03). The frequency of microvessel lesions was lower in males than in females (35 vs. 44%, respectively), although this was not significant. We found no correlation between the frequency of microvessel lesions and age.

Conclusions: In spite of the controversies regarding eosinophilia and microvessel lesions, in this study the number of circulating eosinophils was associated with fewer cardiac lesions. Comparative studies are needed to determine the exact relationship.