What is the pathophysiology of Kawasaki disease?

Updated: Jul 29, 2018
  • Author: Tina K Sosa, MD; Chief Editor: Russell W Steele, MD  more...
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Answer

Despite the prominent mucocutaneous clinical findings that define the illness, KD is best regarded as a generalized vasculitis that involves medium-sized arteries. Although the vascular inflammation is most pronounced in the coronary vessels, vasculitis can also occur in veins, capillaries, small arterioles, and larger arteries.

In the earliest stages of the disease, the endothelial cells and the vascular media become edematous, but the internal elastic lamina remains intact. Then, approximately 7-9 days after the onset of fever, an influx of neutrophils occurs, which is quickly followed by a proliferation of CD8+ (cytotoxic) lymphocytes and immunoglobulin A–producing plasma cells. The inflammatory cells secrete various cytokines (tumor necrosis factor, vascular endothelial growth factor, monocyte chemotactic and activating factor), interleukins (IL-1, IL-4, IL-6), and matrix metalloproteinases (primarily MMP3 and MMP9) that target the endothelial cells and result in a cascade of events that lead to fragmentation of the internal elastic lamina and vascular damage. [9]  In severely affected vessels, the media develops inflammation with necrosis of smooth muscle cells. The internal and external elastic laminae can split, leading to aneurysms.

Over the next few weeks to months, the active inflammatory cells are replaced by fibroblasts and monocytes, and fibrous connective tissue begins to form within the vessel wall. The intima proliferates and thickens. The vessel wall eventually becomes narrowed or occluded owing to stenosis or a thrombus. [10, 11, 12, 13, 14] Cardiovascular death may occur from a myocardial infarction secondary to thrombosis of a coronary aneurysm or from rupture of a large coronary aneurysm. The period during of the greatest vascular damage is when a concomitant progressive increase in the serum platelet count occurs, and this is the point of the illness when the risk of death is most significant.


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