Cutaneous purpura is a capillary and small vessel vasculitis characterized by non-thrombocytopenic cutaneous purpura, which is usually not associated with joint pain, abdominal pain, hematuria, or proteinuria. Cutaneous purpura is usually caused by infection and may be related to streptococcal infection, exposure to allergens, and other factors. Allergenic substances will produce antibodies when they enter the body, which leads to an increase in the permeability and fragility of blood vessels, which in turn causes the occurrence of cutaneous purpura. Cutaneous purpura is characterized by skin involvement, mainly on the extensor side of the lower limbs and buttocks. Bleeding spots vary in size, are often symmetrically distributed, and can be fused with each other. Patients may experience occasional itching, and hemorrhagic necrosis is possible in severe purpura. Patients with cutaneous purpura should go to the hospital in time to identify the cause of the disease under the guidance of the doctor and treat the symptoms.