There are many reasons for pimples on legs, such as: folliculitis, keratosis pilaris, contact dermatitis, eczema and other diseases. 1. Folliculitis: this disease is often caused by bacterial infection of the hair follicle and its surrounding tissues, can appear on the legs of inflammatory papules, pustules, etc., the phenomenon of acne on the legs. 2. Keratosis pilaris: the cause of the disease is unknown, may be related to genetic factors, vitamin A deficiency, metabolic disorders, etc., can appear on the legs of corn size follicular pimples, often accompanied by skin roughness, thus appearing the phenomenon of acne on the legs. 3. Contact dermatitis: when the skin on the legs comes into contact with sensitizing substances, it may cause local allergic reactions, resulting in erythema and papules at the contact site, accompanied by itching, and then the phenomenon of leg pimples appears. 4. Eczema: the cause of the disease is not known, is internal and external factors caused by a variety of inflammatory skin diseases, may be related to genetics, immunity, infection, allergies, etc., the patient may appear erythema, papules, papules, with itching, the phenomenon of leg acne. Acne on the legs may also be caused by other diseases, it is recommended that patients go to the hospital in time for examination, after a clear diagnosis under the guidance of the doctor standardized treatment.