Causes
One proposed cause of pilonidal cysts is ingrown hair. Excessive sitting is thought to predispose people to the condition because they increase pressure on the coccyx region. Trauma is not believed to cause a pilonidal cyst; however, such an event may result in inflammation of an existing cyst. However there are cases where this can occur months after a localized injury to the area. Some researchers have proposed that pilonidal cysts may be the result of a congenital pilonidal dimple. Excessive sweating can also contribute to the cause of a pilonidal cyst.
The condition was widespread in the United States Army during World War II. More than eighty thousand soldiers having the condition required hospitalization. It was termed "jeep seat" or "Jeep riders' disease", because a large portion of people who were being hospitalized for it rode in Jeeps, and prolonged rides in the bumpy vehicles were believed to have caused the condition due to irritation and pressure on the coccyx.
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