Systemic vasculitis is a type of inflammatory disease in which the inflammatory response of blood vessels is the main pathology. The inflammatory lesions of blood vessels lead to impaired blood supply to the corresponding tissues and organs and tissue necrosis. Clinically, the manifestations vary depending on the size, type, and location of the affected vessels, and can be limited to a single organ or involve multiple systems throughout the body. Classification The 2012 Chapel Hill meeting updated the classification of vasculitis: 1. Large vessel vasculitis Large arteritis, giant cell arteritis 2. Medium vessel vasculitis Nodular polyarteritis, Kawasaki disease 3. Small vessel vasculitis ① ANCA-associated small vessel vasculitis Microscopic polyangiitis, granulomatous polyangiitis (Wegener’s granulomatosis), eosinophilic granulomatous polyangiitis (Churg- Strauss syndrome) ② immune complex small vasculitis anti-glomerular basement membrane (anti-GMB) disease, cryoglobulin vasculitis, IgA vasculitis (allergic purpura), hypocomplementemic urticarial vasculitis (anti-C1q vasculitis) 4. variant vasculitis Leukoaraiosis, Cogan syndrome 5. single organ vasculitis cutaneous leukocytoclastic vasculitis, cutaneous arteritis, primary neurological vasculitis, pure aortitis 6, systemic disease-related vasculitis lupus erythematosus vasculitis, rheumatoid arthritis vasculitis, nodular disease vasculitis 7, etiology-related vasculitis hepatitis C virus-related cryoglobulinemia vasculitis, hepatitis B virus-related vasculitis, syphilis-related vasculitis, serum disease-related immune complex-related vasculitis, drug-related immune complex-related vasculitis, Drug-associated ANCA-associated vasculitis, tumor-associated vasculitis Clinical manifestations No specific clinical manifestations, the following conditions should be considered as possible vasculitis 1. General: fever, weight loss, malaise, fatigue, anorexia 2.Musculoskeletal: myalgia, arthralgia, arthritis, mastication disorder or intermittent claudication of the limbs. 3.Skin: reticular cyanosis, purpura, erythema nodosum, urticaria, etc. 4.Nervous system: headache, cerebrovascular disease, vision changes, single or multiple peripheral neuritis. 5, Respiratory system: sinusitis, hemoptysis, asthma, alveolitis, intrapulmonary nodules, pulmonary infiltrative lesions. 6, kidney: renal hypertension, proteinuria, abnormal urinary sediment, necrotizing glomerulonephritis. 7, digestive system: diarrhea, abdominal pain, gastrointestinal bleeding, elevated liver enzymes. 8, abnormal laboratory tests: anemia, thrombocytopenia, hypocomplementemia, hypergammaglobulinemia, increased sedimentation, elevated C-reactive protein, etc. The above manifestations can also be seen in infections, tumors and other diseases, but they cannot be explained by common diseases, especially when multiple systems are involved and acute chronological reactants (ESR, CRP) are abnormal, the presence of vasculitis should be highly suspected and further appropriate tests should be done. Laboratory tests Some patients with vasculitis are positive for anti-neutrophil cytoplasmic antibodies (ANCA), where the target antigen of cytoplasmic ANCA (cANCA) is mainly proteinase 3 (PR3). cANCA combined with positive PR3 is 99% specific for the diagnosis of Wegener’s granulomatosis; the target antigen of perinuclear ANCA (pANCA) is mainly myeloperoxidase (MPO). pANCA combined with positive MPO diagnoses microscopic polyangiitis. Treatment Glucocorticoids combined with immunosuppressive agents are generally applied.