(See also Overview of the Anus and Rectum.)
Pilonidal disease usually occurs in young, hairy men but can also occur in women.
For unknown reasons, sometimes a hair irritates and grows into the skin, forming a cavity that may thus contain hair. Such a cavity is called a pilonidal cyst and typically forms at the top of the cleft between the buttocks. The cyst may cause no symptoms, or it may become infected and cause pain. If the infection causes a collection of pus to form, it is called a pilonidal abscess. A pilonidal sinus is a chronic draining wound at the site.
A pilonidal abscess causes pain, redness, and swelling. Sometimes pus drains spontaneously from the abscess.
Generally, a pilonidal abscess must be cut and drained by a doctor. Antibiotics are typically not needed.
Usually, a pilonidal sinus must be removed surgically.
Larger cysts may need to be closed with a flap procedure. In a flap procedure, skin and sometimes muscle are moved from a nearby area to cover the area that the cyst was removed from.