Pilonidal dimple is a condition that can occur anywhere along the crease between the buttocks, which runs from the bone at the bottom of the spine (sacrum) to the anus.

Pilonidal dimple may appear as:

• A pilonidal abscess, in which the hair follicle becomes infected and pus collects in the fat tissue
• A pilonidal cyst, in which a cyst or hole forms if there has been an abscess for a long time
• A pilonidal sinus, in which a tract grows under the skin or deeper from the hair follicle
• A small pit or pore in the skin that contains dark spots or hair

Pilonidal abscess; Pilonidal sinus; Pilonidal cyst; Pilonidal disease

Symptoms may include:

• Pus may drain to a small pit in the skin
• Tenderness over the area after you are active or sit for a period of time
• Warm, tender, swollen area near the tailbone
• Fever (rare)

There may be no symptoms other than a small dent (pit) in the skin in the crease between the buttocks.

The cause of pilonidal disease is not clear. It is thought to be caused by hair growing into the skin in the crease between the buttocks.

This problem is more likely to occur in people who:

• Are obese
• Experienced trauma or irritation in the area
• Have excess body hair
• Sit for long periods of time
• Wear tight clothing

It may help to keep the area clean and dry and remove hair regularly to prevent infection.

Call your health care provider if you notice any of the following around the pilonidal cyst:

• Drainage of pus
• Redness
• Swelling
• Tenderness

You will be asked for your medical history and given a physical examination. Sometimes you may be asked for the following information:

• Has there been any change in the appearance of the pilonidal cyst?
• Has there been any drainage from the area?
• Do you have any other symptoms?

Rarely, a CT scan is done.

Pilonidal disease that causes no symptoms does not need to be treated.

A pilonidal abscess may be opened, drained, and packed with gauze. Antibiotics may be used if there is an infection spreading in the skin or you also have another, more severe illness.

Other surgeries that may be needed include:

• Removal (excision) of the diseased area
• Skin grafts
• Surgery to remove an abscess that returns

Stafford SJ, Klein MD. Pilonidal sinus and abscess. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 336.6.

Nelson H, Cima RR. Anus. In: Townsend CM Jr, Beauchamp RD, Evers BM, Mattox KL, eds. Sabiston Textbook of Surgery. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 51.

Humphries AF, Duncan JE. Evaluation and management of pilonidal disease. Surg Clin North Am. 2010;90:113-124.