A Pilonidal (PIE-low-NI-dal) Cyst usually consists of a hair-containing sinus or abscess, just above the cleft of the buttocks under the skin over the tailbone (coccyx). The term pilonidal comes from a combination of Latin words meaning hair (pilus) and nest (nidal). Pilonidal cyst is more common in men than in women, usually occurring after puberty. The origin of the problem is not well understood. Some evidence suggests that it may be congenital or that it's acquired by an ingrowth of hair. For a time, the entity was referred to as Jeep Rider's disease. It caused more than 80,000 US Army soldiers to be hospitalized during WWII and accounted for 4.2 million sick days. Much of the information we have about the disease comes from the military. The main problem with pilonidal cysts are the occurrence of infection that leads to a painful abscess. The abscess may rupture, drain spontaneously and then resolve only to recur. After the abscess resolves, either by itself or with medical assistance, many patients develop a pilonidal sinus. The sinus is a cavity below the skin surface that connects to the surface with one or more small openings or tracts. Although a few of these sinus tracts may resolve spontaneously, most patients need a small operation to eliminate them.
