Medically reviewed by Mary Choy, PharmD A pilonidal cyst, sometimes called pilonidal disease, is a fluid-filled sac that usually occurs on the tailbone at the top of the buttocks. It usually starts as ...

While seeing or feeling a cyst can seem worrisome ... These methods include: Hair removal: Since ingrown hairs cause pilonidal sinus, hair removal techniques (e.g., waxing, shaving, and laser ...