Vasculitis is an inflammation with inflammatory cell infiltration in the vascular wall and around the blood vessels, accompanied by vascular damage, including cellulose deposition, collagen fiber degeneration, endothelial cell and muscle cell necrosis, also known as vasculitis. Primary vasculitis is caused by pathogenic factors acting directly on the vascular wall, and vasculitis is caused by certain clinical symptoms and signs on the basis of vascular inflammation; secondary vasculitis is caused by inflammatory lesions of adjacent tissues affecting the vascular wall, which is only one of the pathological changes of multiple tissues and is different from vasculitis. In addition, in the so-called collagen vascular disease, vascular damage is one of the main concomitant lesions, so this type of disease belongs to the broad sense of vasculitis. Vasculitis is not uncommon. Vasculitis lesions not only affect the blood vessels themselves, but also the tissues and organs controlled by the blood vessels. Some can be fatal. Since the application of corticosteroids, the prognosis has been greatly improved. The clinical symptoms and signs of vasculitis vary depending on the type, size and function of the blood vessels.