Ulcer
Ulcers can be from infection with germs. Ulcers can be from pressure on a part of the skin. Ulcers can be from substances that will burn skin or mucous membranes. When acid makes some stomach ulcers this is from burning by the acid. Ulcers can be from cancer. Ulcers can be from diseases of blood vessels. If not enough blood goes to a body part, it can get an ulcer.