Pilonidal disease was first described by Hodges in 1880  and is diagnosed by the finding of a characteristic epithelial track (the sinus) situated in the skin of the natal cleft, a short distance behind the anus and generally containing hair, hence the name pilonidal taken from the Latin, meaning literally 'nest of hairs'. During the Second World War the condition was common in jeep drivers, which led to it being known as 'jeep disease'. A similar condition arises in the clefts between the fingers of barbers or hairdressers caused by customers' hair entering moist, damaged skin.
The onset of PNS is rare both before puberty and after the age of 40. Males are affected more frequently than females, probably due to their more hirsute nature . In a population study of 50,000 students the incidence in males was 1.1%, ten times more than in females , although many of these were asymptomatic. Figures from the Office of Population Censuses and Surveys (1985) record 7,000 patients as having had inpatient treatment for PNS in England. Proportionately females make up a quarter of those undergoing hospital treatments , possibly reflecting under-reporting in the male population. The condition is more common in Caucasians than Asians or Africans due to differing hair characteristics and growth patterns . In a study of risk factors the following associations were found