abscess, localized inflamation associated with tissue necrosis. Abscesses are characterized by inflamation, which is due to the accumulation of pus in the local tissues, and often painful swelling. They occur in the skin, at the root of a tooth, in the middle ear, on the eyelid (see sty), in the mammary glands, in the recto-anal area, and elsewhere in the body. Abscesses may develop in lung tissue, in the lymph nodes, and in bone. A sinus abscess may result in a fistula, and abscess of the appendix in appendicitis. Unless an abscess discharges spontaneously, surgical incision and drainage is required. See boil; carbuncle.