The top of the buttocks, where they separate, has a small hole or tunnel in the skin called a pilonidal sinus (the cleft). It does not always result in symptoms, and only when it becomes infected does it require treatment. The top of the buttocks, where they separate, has a small hole or tunnel in the skin called a pilonidal sinus (the cleft). It does not always result in symptoms, and only when it becomes infected does it require treatment.
The top of the buttocks, where they separate, has a small hole or tunnel in the skin called a pilonidal sinus (the cleft). It does not always result in symptoms, and only when it becomes infected does it require treatment. The top of the buttocks, where they separate, has a small hole or tunnel in the skin called a pilonidal sinus (the cleft). It does not always result in symptoms, and only when it becomes infected does it require treatment.