| Abscesses occur when an area of tissue becomes infected and the body's immune system tries to fight it. White blood cells move through the walls of the blood vessels into the area of the infection and collect within the damaged tissue. During this process, pus forms. Pus is the buildup of fluid, living and dead white blood cells, dead tissue, and bacteria or other foreign substances. Abscesses can form in almost any part of the body. The skin, under the skin, and the teeth are the most common sites. Abscesses may be caused by bacteria, parasites, and foreign substances. |