The term "ulcer" comes from a Latin word meaning an open sore. An ulcer involves damage to the skin or mucous membrane that reaches into the lower layers of the skin. An ulcer can occur in or on different parts of the body, including the stomach, lower bowel, the leg or as a bed sore (for example, on the heel or base of the spine) in people who are in bed long term. Particular factors can lead to ulcers, including circulation problems, infections, tumours, diabetes or blood vessel diseases like peripheral vascular disease. An ulcer is often painful and it often takes a long time to heal.