Furuncle in the abdominal skin. A furuncle is a deep infection of a hair follicle. Also the surroundings of the follicle have become infected. The origin is a small papule that has developed to an aching and very tender reddened nodule with a necrotic purulent top. This furuncle is already ripened, and an incision will thus provide a rapid soothing of the pain. A first generation cephalosporin is also started if needed.