Purpura is a manifestation of subcutaneous hemorrhage, and we call such a bleeding spot, which is about 3-5 mm in diameter, purpura. There are many types of skin manifestations of vasculitis that can present with purpura, for example, about 50% of patients with polyarteritis nodosa can present with skin damage, and purpura is a manifestation of skin damage. Also, about 70% of patients with ANCA-associated vasculitis can have skin manifestations, and the skin manifestations are also predominantly purpuric. Of course, there are also some that can be seen, such as reticulocyanosis or ulceration, and so on. Does the presence of purpura necessarily mean vasculitis? Not necessarily. We have to combine the appearance of purpura with other symptoms of the patient and relevant antibody tests to be able to diagnose vasculitis. In addition, the presence of purpura should be differentiated from allergic vasculitis and allergic purpura, which have a history of allergy. After the appearance of purpura in the clinic, we need to take into account the patient’s medical history, as well as the existing symptoms, physical examination results, and relevant blood test results, to make a further diagnosis.