Vasculitis is a group of heterogeneous diseases with inflammation and destruction of blood vessels as the main pathological changes. Its clinical manifestations vary depending on the type, size, location and pathological characteristics of the affected blood vessels. Vasculitis can be a single disease or one of the clinical manifestations of a certain disease, such as systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, tumors, and infections; it can be systemic, causing dysfunction of multiple system organs, or it can be limited to a certain organ. In view of the complexity and diversity of vasculitis, it can be called vasculitis syndrome. The prognosis of vasculitis depends on the size, number and location of the affected blood vessels.