What is pilonidal disease?
Pilonidal (say "py-luh-NY-dul") disease is a chronic skin infection in the crease between the buttocks. People with this condition have one or more cysts in that area that tend to get inflamed and infected. A pilonidal cyst may look like a small dimple (called a "pit" or "sinus"). Hair may stick out from it.
See a picture of a pilonidal cyst .
What causes a pilonidal cyst?
Experts think pilonidal cysts may form in one of three ways:
- A hair follicle in the skin becomes irritated or stretched. This may be caused by exercise that affects the buttocks area (such as horseback riding or cycling), tight clothing around the buttocks, heat, or heavy sweating. The hair follicle may become blocked and infected and then open into the surrounding tissue, forming an abscess. Continued exercise or walking often pulls hair into the abscess.
- A loose hair may get trapped in the crease between the buttocks. This is more common with coarse or stiff hair. The hair can poke into the skin, especially if there is already an irritated hair follicle. Walking and exercise can pull the hair farther into the skin. A cyst then forms around the hair and can become infected.
- Some cysts may be present at birth (congenital).
What are the symptoms?
Pilonidal disease often has no symptoms. If a cyst gets infected (called an abscess), you may have:
- Redness or swelling.
- Pus or blood draining from the abscess.
- Pain when you walk or sit.
How is pilonidal disease diagnosed?
A physical exam of the buttocks is usually all doctors need to diagnose pilonidal disease. You probably won't need any other tests unless the area doesn't heal or your doctor thinks there may be another problem.