Pilonidal Cyst

  • Medical Author:
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

  • Medical Editor: Jerry R. Balentine, DO, FACEP
    Jerry R. Balentine, DO, FACEP

    Jerry R. Balentine, DO, FACEP

    Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

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What is a pilonidal cyst?

A pilonidal cyst is a sac filled with debris and hair that occurs in the area at the top of the crease of the buttocks overlying the tailbone (sacrum). This cyst and the overlying skin in the area can become infected, forming a painful abscess.

What causes a pilonidal cyst?

It is not clear why pilonidal cysts form. At one time, it was thought pilonidal cysts might be congenital (a person is born with them) arising from embryologic cells that were in the wrong place early in development or due to repeat trauma (jeep driver's disease). It is now thought that small groups of hairs and debris (dead skin cells and bacteria) get trapped in the pores of the skin in the upper cleft of the buttock and form a "sinus," or pocket, that grows to become an abscess. This abscess forms under the skin (subcutaneously) and can result in scar tissue that can become infected repeatedly.

Some babies are born with an indentation just above the crease of the buttocks called a sacral dimple. If the sacral dimple becomes infected, it can become a pilonidal cyst.

Picture of a pilonidal cyst
Picture of a pilonidal cyst

What are risk factors for a pilonidal cyst?

Risk factors for pilonidal cysts include the following:

  • Male predominance (four times more often than in women)
  • Young age (most commonly found in men in their 20s)
  • Sedentary lifestyle
  • Thick body hair
  • Family history
  • Local shaving or damage to the skin from friction
  • Overweight or obese
  • Previous pilonidal cyst
Medically Reviewed by a Doctor on 6/2/2016

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