Skin appeared a piece of small white bumps, consider for urticaria, folliculitis, cornu rashes and other diseases caused. 1. urticaria: urticaria belongs to allergic skin diseases, is the skin mucosa because of the temporary increase in vascular permeability, caused by the phenomenon of local skin edema, if the phenomenon of urticaria edema is more serious, can also cause urticaria white, the formation of a piece of a small white bumps. 2. Folliculitis: generally local hair follicles are infected by bacteria and fungi and other infections, which can lead to the formation of local hair follicles red papules, and accompanied by redness, swelling, heat and pain and other phenomena, when there is an acute suppurative inflammation, papules on top of the yellow-white pus plugs, so it looks like a small white pimple. 3. Corns: they are retention cysts originating from the epidermis and the epithelium of the appendages, and are found on the face and around the eyelids or in the underlying lesion areas, manifesting as yellowish-white, firm papules, which look like a patch of small white bumps. There are many reasons for the appearance of small white bumps on the skin, it is recommended to go to the hospital to complete the examination, after a clear diagnosis under the guidance of the doctor for reasonable treatment.