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Merck Manual

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Pilonidal Disease


Parswa Ansari

, MD, Hofstra Northwell-Lenox Hill Hospital, New York

Last full review/revision Feb 2021| Content last modified Feb 2021
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Pilonidal disease is an infection caused by a hair that injures the skin at the top of the cleft between the buttocks.

  • This disorder occurs when hairs near the buttocks grow into the skin.

  • If an infection develops, symptoms include pain, redness, and swelling and sometimes pus.

  • The diagnosis is based on an examination.

  • Treatment includes measure to remove abscesses and sinuses and repair cysts.

Pilonidal disease usually occurs in young, hairy men but can also occur in women.

For unknown reasons, sometimes a hair irritates and grows into the skin, forming a cavity that may thus contain hair. Such a cavity is called a pilonidal cyst and typically forms at the top of the cleft between the buttocks. The cyst may cause no symptoms, or it may become infected and cause pain. If the infection causes a collection of pus to form, it is called a pilonidal abscess. A pilonidal sinus is a chronic draining wound at the site.

A pilonidal abscess causes pain, redness, and swelling. Sometimes pus drains spontaneously from the abscess.


  • A doctor's examination

To distinguish pilonidal disease from other infections, a doctor looks for tiny holes in or next to the infected area (pits).


  • For pilonidal abscesses, cutting and draining

  • For pilonidal sinuses, surgical removal

  • For larger cysts, flap procedure

Generally, a pilonidal abscess must be cut and drained by a doctor. Antibiotics are typically not needed.

Usually, a pilonidal sinus must be removed surgically.

Larger cysts may need to be closed with a flap procedure. In a flap procedure, skin and sometimes muscle are moved from a nearby area to cover the area that the cyst was removed from.

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