Definition: necrotizing vasculitis with asthma and eosinophilia, involving the respiratory tract, with massive eosinophil infiltration and extravascular granuloma formation, affecting small to medium-sized vessels. Epidemiology: The incidence is relatively low (2.5/100,000/year), with a male to female ratio of 2:1 and an age of onset of 15-70 years, with a mean age of 38 years. Clinical manifestations: Respiratory system 1. Allergic or allergic rhinitis: often the initial symptom, 70% of patients can present with such manifestations. The main symptom is nasal congestion and discharge of purulent or bloody secretions. Occasionally, the nasal septum is perforated. Extravascular granuloma formation with eosinophilic infiltration of tissue is common on nasal mucosal biopsy. 2. Asthma: one of the main manifestations. It occurs in about 80%-100% of patients during the course of the disease and is not easily controlled by general medications. The severity of asthma attacks does not necessarily correspond to the severity of systemic systemic damage. 3. Infiltrative lesions in the lungs: one of the main manifestations of the respiratory system of CSS, with a maximum frequency of up to 93%. Eosinophilic pneumonia is the main manifestation of intrapulmonary lesions in CSS. Mutability is its characteristic feature. 4. Other respiratory manifestations: 27% of patients can develop pleural effusion and pleural friction sounds, and in severe cases, alveolar hemorrhage. Neurological system: 62% can show neurological damage, which is one of the early manifestations of systemic vasculitis. The main involvement is peripheral nerve involvement, commonly multiple mononeuritis, symmetric polyneuropathy or asymmetric polyneuropathy. Rarely, cranial nerves are involved. Central nerve involvement is less common, often late in the course of the disease. Cerebral hemorrhage or cerebral infarction is uncommon, with severe single consequences, and is a common cause of death. Skin manifestations: More than 50% of patients present with various skin lesions. 3 types of rashes are common: red maculopapular rash, hemorrhagic rash, and cutaneous or subcutaneous nodules. Of these, cutaneous and subcutaneous nodules are highly specific for CSS. Cardiovascular system: The heart is one of the major target organs for CSS. The main lesions are acute constrictive pericarditis, heart failure and myocardial infarction, and sometimes mitral valve prolapse is seen. Cardiac involvement is often the leading cause of death in CSS. Digestive system: abdominal pain, diarrhea and gastrointestinal bleeding are common, and severe ischemia can lead to perforation due to damage to the mucosa of the gastrointestinal tract. Involvement of the peritoneum results in ascites. Colonic involvement is less common, and involvement manifests as multiple ulcers in the ileocecal and descending colon, with pus and blood stools or scanty stools. Urological system: 84% of patients can present with various renal diseases, mainly microscopic hematuria and proteinuria, which can resolve on their own. another characteristic of CSS is that it more often affects the lower urethra and prostate, causing the corresponding symptoms of the disease. Ocular manifestations: less frequently involved. Occasionally, inflammation of the corresponding parts of the conjunctiva, sclera, and uvea occurs, with ulcer formation on the corneal limbus, scleral nodules, ischemic optic neuritis, and very rarely, retinal arteritis. Joints and muscles: All joints can be involved, manifesting as wandering arthralgia, and there may be joint swelling. No destructive bone or cartilage changes are seen. Spastic pain of the gastrocnemius muscle is the most characteristic. Laboratory tests: 1, blood routine: peripheral blood eosinophilia, the absolute value is usually above 1.5*109/L, accounting for 10%-50% of peripheral blood, is one of the characteristic indicators of CSS. 2.Immunological abnormalities: IgE is elevated in the serum. 70% of ANCA are positive, mainly P-ANCA, but CSS cannot be excluded in negative cases. 3.Cardiac ultrasound: Involvement of the heart is mostly abnormal, and mitral valve prolapse is seen in those involving the myocardium and cardiac vessels. 4.X-ray: chest X-ray is not characteristic. Pleural effusion is seen in 27% of cases. 5.Pulmonary CT: Hairy glass-like pulmonary solid shadows similar to eosinophilic pneumonia are seen. Pathology: typical pathological changes. (1) Massive eosinophilic infiltration of tissues and blood vessel walls. (2) Perivascular granuloma formation. (3) Staged fibrinoid necrotizing vasculitis. Diagnostic criteria: 1990 American College of Rheumatology classification criteria: 1. Asthma: history of asthma or diffuse high-pitched rales in the lungs on expiration. 2, Eosinophilia: >10% eosinophils in the white blood cell count 3, Solitary or multiple neuropathy: mononeuropathy, multiple mononeuropathies or polyneuropathies (glove/glove-like distribution) due to, in systemic vasculitis. 4. non-fixed pulmonary infiltrates: migrating or transient pulmonary infiltrates on chest radiographs due to systemic vasculitis (excluding fixed infiltrative shadows) 5. paranasal sinusitis: history of acute or chronic paranasal sinus pain or pressure, or imaging showing blurring of the paranasal sinus area 6. Extravascular eosinophilic infiltration: biopsy including arteries, small arteries or small veins shows extravascular eosinophil accumulation. CSS can be diagnosed if 4 or more of the above items are met. Differential diagnosis: Differentiate from other systemic and necrotizing vasculitis, other diseases with peripheral blood eosinophilia and bronchial asthma or wheezing bronchitis, such as polyarteritis nodosa, hypereosinophilic syndrome, Wegener’s granulomatosis, and chronic eosinophilic pneumonia. Treatment principles: 1, glucocorticoids are preferred. 2, immunosuppressive drugs: 20% of patients with severe disease or combined with impaired function of major organs need to add immunosuppressive drugs. Mostly cyclophosphamide, followed by azathioprine, mycophenolate, etc. Prognosis: The most common causes of death are myocarditis and myocardial infarction secondary to coronary vasculitis. The prognosis is better with early and effective treatment.