A pilonidal sinus literally means ?nest of hairs?. This is a condition that arises when hair penetrates the skin between the buttocks (the natal cleft).
When this happens, there can be a range of different symptoms. In some cases, there are few symptoms. In other cases, there can be recurring infections or abscesses in the area. These symptoms can be painful.
The hair can sometimes cause pits in the skin. Treatment involves removing these pits so that healing can occur.