What is a pilonidal cyst?
A pilonidal cyst is a fluid-filled sac (cyst) that develops along the tailbone (coccyx) near the cleft of the buttocks. These cysts usually contain hair and skin debris. The term pilonidal is derived from the Latin words pilus (hair) and nidus (nest). Individuals with a pilonidal cyst may not have any symptoms at all or they may develop infection of the cyst (pilonidal abscess) with associated pain and inflammation. What causes a pilonidal cyst? Though there are several theories, most researchers believe that pilonidal cysts are caused by the penetration of loose hairs into the skin. In response to this ingrown hair, a local inflammatory reaction causes a cyst to form around the hair. Excessive pressure or repetitive traumas to the sacrococcygeal area are thought to predispose individuals to develop the cysts. These conditions can also irritate existing pilonidal cysts. During World War II, more than 80,000 soldiers developed pilonidal cysts requiring hospitalization. Because so many o
