Henoch-Schonlein purpura dermatosis is a group of chronic dermatoses characterized by purpura-like papules and hemosiderosis. Lichen-like dermatitis pigmentosa is common in middle-aged and elderly people, with more males than females. The lesions are tiny rust-colored mossy papules with purpura-like lesions, which are purplish red or purplish brown. Can be mixed with patches with unclear boundaries, with a little scale on the surface and petechiae on the edge. Usually occurs in the calf, but also can develop upward to the thigh, buttocks, waist and upper limbs, with varying degrees of itching. The course of the disease is chronic and can last for several months to several years.