Kawasaki disease (KD), also known as mucocutaneous lymphnode syndrome (MCLS), is an acute febrile rash disease with inflammatory lesions of small and medium-sized arteries throughout the body as the main pathological changes. Since its report by Tomisaku Kawasaki in Japan in 1967, its awareness has been increasing, and its incidence has been increasing in recent years both at home and abroad, and it has become one of the common diseases in pediatrics. Due to the presence of atypical cases and the lack of diagnostic tests in the early stages of the disease, the delay in diagnosis and treatment is one of the main causes of coronary artery lesions. Therefore, the vigilance of this disease should be strengthened to strive for early diagnosis and early treatment in order to reduce the occurrence of complications. Epidemiological data suggest that rickettsiae, propionibacterium, staphylococci, streptococci, retroviruses, and mycoplasma infections are the causes of the disease, but they have not been confirmed. Pathogenesis: The pathogenesis of the disease is not clear. It is presumed that specific components of the infectious agent, such as superantigens (heat shock protein 65, HSP65, etc.) may not pass through monocytes/macrophages. directly by binding to T cell antigen receptor (TCR) VB fragments and activating CD30+ T cells and CD40 ligand expression. It leads to damage of the vessel wall. IV. Pathology The pathological changes of the disease are systemic vasculitis with a predilection for coronary arteries. The pathological process can be divided into four stages, and the changes in each stage are as follows: Stage I About 1 to 9 days, periarterial inflammation with invasion of small nutrient arteries and veins in the vessel walls of the major branches of the coronary arteries. The pericardium, myocardial interstitium and endocardium are infiltrated with inflammation, including neutrophils, eosinophils and lymphocytes. Stage II Approximately 12 to 25 days later, the major branches of the coronary arteries are fully vascularized with endothelial edema and inflammatory cell infiltration of the smooth muscle layer of the vessel wall and the outer membrane. The elastic fibers and myofibrils break down, and thrombi and aneurysms may form. Stage III In about 28 to 31 days, the arterial inflammation gradually subsides, thrombus and granulation form, fibrous tissue proliferates, and the intima thickens significantly, leading to partial or total obstruction of the coronary artery. Stage IV Several months to years, the lesion gradually heals, myocardial scar formation, and the blocked artery may be recanalized. V. Diagnosis and differential diagnosis: 1. Diagnostic criteria for Kawasaki disease Fever for more than 5 days, with 4 of the following 5 clinical manifestations, after excluding other diseases, can be diagnosed Kawasaki disease: (1) changes in the extremities: acute palmoplantar erythema, hard edema of the hands and feet; recovery period, membranous debridement of the ends of the fingers and toes (2) polymorphic erythema (3) congestion of the conjunctiva of the eyes, non-purulent (4) lip congestion and chapping, diffuse congestion of the oral mucosa, tongue (5) enlarged lymph nodes in the neck Note: If there are less than 4 out of 5 clinical manifestations, but there is coronary artery damage on echocardiogram, Kawasaki disease can be diagnosed. 2. IVIG non-sensitive KD There is no unified definition for the diagnosis of this disease, and there are also various expressions such as IVIG non-responsive KD, IVIG resistant KD and refractory KD. Most believe that a child with KD who receives IVIG 2g/Kg within 10 days of onset and still has a body temperature higher than 38℃ for 48 hours regardless of a single or split infusion, or has a fever again after 2~7 days (or even 2 weeks) of administration, and meets at least one of the KD diagnostic criteria, can be considered as IVIG non-sensitive KD. VI. Treatment Aspirin 30~50mg/kg daily in 2~3 doses , gradually reduce the dosage 3 days after the fever subsides to 3~5mg/kg per day for about 2 weeks and maintain for 6~8 weeks. If coronary artery lesions are indicated, the duration of medication should be extended until the coronary arteries return to normal. Intravenous injection of gammaglobulin The dose of 1-2g/kg is input slowly in 8~12 hours, (online information often has the statement of 1-2 hours rapid infusion, this method is suitable for small doses such as: 400mg/kg, large doses are inappropriate, because the speed is too fast and easy to occur heart failure) is suitable for early onset (within 10 days) application, can quickly reduce fever, prevent the occurrence of coronary artery lesions, should be combined with the application of Aspirin. Some children are not effective with IVIG, and it can be repeated 1~2 times, but it is still ineffective in about 1%~2% of cases. Children with IVIG should not be vaccinated against measles, rubella, mumps, etc. within 9 months. Glucocorticoids should not be used alone because they can promote thrombosis, predispose to coronary artery aneurysm and affect the repair of coronary lesions, and can be combined with aspirin and bimatoprost in children who have failed IVIG treatment. The dose is 2 mg/kg daily for 2-4 weeks. VII. Prognosis and follow-up Kawasaki disease is a self-limiting disease and most of them have a good prognosis. Recurrence is seen in 1%-2% of children. Children without coronary artery lesions should undergo a comprehensive examination (including physical examination, electrocardiogram and echocardiogram) at 1, 3, 6 months and 1-2 years after discharge from the hospital. In children without effective treatment, coronary artery aneurysms occur in 15%-25% of children, so they should be followed up closely for a long time, once every 6-12 months. Most coronary aneurysms disappear spontaneously within 2 years after the disease, but functional abnormalities such as wall thickening and reduced elasticity are often left behind. Large aneurysms often do not disappear easily and often lead to thrombosis or narrowing of the lumen. People with coronary aneurysms need to take aspirin for a long time until the aneurysm disappears, and limit exercise appropriately.