For over a hundred years, the etiopathogenesis of the pilonidal sinus was considered embryonic. This theory has now been abandoned. The pathogenesis is still not fully understood. It is currently assumed to be of multifactorial origin. The pilonidal sinus is thought to form as a dimple-like indentation in the natal cleft directly above the coccyx. Here, mechanical stress, especially when sitting (jeep driver disease), causes stretching of hair follicles, which eventually rupture. With constant maceration, germs and particularly broken hairs penetrate, leading to acute or chronic inflammation. The doughy soft tumor spreads through a widely used fistula system to the sides and in extreme cases also to the anus.
One or more of the following factors are discussed as risk factors for the development of a pilonidal sinus:
- Heavy hair growth
- Deep gluteal cleft (overweight)
- Local irritation
- Insufficient hygiene
- Positive family history