Buns on the penis may be caused by acute injury, infectious factors, warts, penile cancer and other factors. 1. Acute injury: the penile area suffered an external blow, penile local damage, may quickly appear swelling, will lead to the penis on the long bag, accompanied by pain and subcutaneous bruising. 2. Infection factors: not pay attention to daily care, the appearance of the foreskin glans, for the penis localization caused by the stimulation, will also make the local long bag, may also be accompanied by itching, pain, oozing and other symptoms. 3. Condyloma acuminatum: it is a sexually transmitted disease, mostly caused by unclean sex, which will lead to the appearance of localized cauliflower pattern bumps on the penis, and the area will gradually increase, and it may also be accompanied by mild itching and pain, and it is infectious to a certain extent. 4. Penile cancer: it may be caused by HPV infection, prolonged smoking, long foreskin and other factors, which can lead to the appearance of localized swelling on the penis, and the area of the swelling will gradually increase, accompanied by pain, oozing, erosion and other symptoms. If you have a bag on your penis with obvious abnormal symptoms, you should consult a doctor in time.