Common leg skin diseases include eczema, which is an allergic skin disease. The rash manifestation is symmetrically distributed and characterized by erythema, papules, papules and even pustules, as well as vesicles and exudation, and will be accompanied by significant itching. If it is in the spring, summer, or even travel outdoors, it is common to see insect bite dermatitis, which is a localized allergic skin reaction caused by mosquitoes, fleas, mites and other insects, and the rash is mostly erythema and papules on exposed areas, also accompanied by pronounced itching. The common calf area and allergic purpura, belongs to the subcutaneous capillary rupture and caused by skin problems, rash performance is pinpoint to corn size bruises, bruises, and finger pressure does not fade, generally that is purpura.