The left buttocks long painless small bags may be common warts, lipoma and other diseases caused. 1. common warts: mainly caused by human papillomavirus infection, skin breakage, weak immune system, contact with the patient and other reasons will also trigger the disease. The patient’s main manifestation is the proliferation of warts, which can exist for a long time, and can be seen in any part of the body, usually does not cause self-conscious symptoms. 2. Lipoma: the cause of the disease is not clear, may be related to genetic, chronic inflammation and other factors. Usually manifested as one or more lumps under the skin, can grow in any part of the fat, usually does not produce pain, itching. Left buttocks long painless itchy small bag has more causes, it is recommended to go to the regular hospital to consult the examination, to clarify the cause of the disease.