Kawasaki Disease

Kawasaki disease (KD) is an acute, self-limited systemic vasculitis of unknown etiology that predominantly affects children under 5 years. The pathogenesis involves an aberrant immune response, likely triggered by an infectious agent in genetically susceptible individuals. The inflammatory cascade begins with activation of the innate immune system, with neutrophils and macrophages infiltrating medium-sized arterial walls. This is followed by an adaptive immune response with T cells and IgA-producing plasma cells. The inflammation targets the vasa vasorum (tiny blood vessels supplying the arterial wall), causing necrotizing arteritis that destroys the internal elastic lamina and media of coronary arteries. This destruction leads to coronary artery aneurysm formation in 25% of untreated children. Aneurysm formation creates areas of blood stasis, promoting thrombus formation that can cause MI or sudden cardiac death. Myocarditis with inflammatory infiltration of the myocardium occurs in the acute phase, contributing to cardiac dysfunction. The inflammatory markers (ESR, CRP, WBC) are markedly elevated, and thrombocytosis typically appears in the subacute phase (days 10-25), further increasing thrombotic risk.