The first of these is a pimple on the leg, which is commonly caused by the following diseases: 1. sebaceous cysts, which are caused by the blockage of hair follicles, the dander and oil inside the formation of a benign lesion, need to be removed when the non-red swelling, the prognosis is better. 2. mosquito bites, you can apply toothpaste or topical drugs locally, do not squeeze hard, scratch the itch, slowly improve. 3. swollen lymph nodes, which is often due to infection, which is often due to the infection. If the pain is strong or increasing, you need to go to the hospital in time. 4, local hematoma caused by trauma, if the history of previous trauma can be clarified, in the local can be hot compresses to help the absorption of the hematoma. 5, there are other causes, such as parasitic diseases, such as the persistence of the swelling, it is recommended to consult the surgery in time to clarify.