Pilonidal Cyst

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Pilonidal cyst facts

  • Pilonidal cysts are fluid-filled sacs that form at the top of the crease of the buttocks above the sacrum. A painful abscess can form if the cyst and the overlying skin become infected.
  • Pilonidal cysts are caused by groups of hairs and debris trapped in the pores of the skin in the upper cleft of the buttock, forming an abscess.
  • Risk factors for pilonidal cysts include being male, sedentary, having thick body hair, family history, being overweight, and previous pilonidal cysts.
  • Symptoms of pilonidal cysts include
    • pain,
    • redness,
    • swelling,
    • fever,
    • if the abscess ruptures, there may be discharge of blood or pus.
  • Treatment for pilonidal cysts involves incision and drainage (I&D) or surgery.
  • Home remedies include sitz baths and some vitamin supplements.
  • The prognosis for a pilonidal cyst is generally good. Recurrences are common.

What is a pilonidal cyst?

A pilonidal cyst is a fluid-filled sac 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.

Picture of a pilonidal cyst
Picture of a pilonidal cyst

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.

Medically Reviewed by a Doctor on 3/2/2015

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Pilonidal Cysts: What Are the Risk Factors?

Most experts believe that the cysts arise due to trauma to the area that results in ingrown hairs. Pilonidal cysts often contain hair when excised, but hair follicles have not been demonstrated in them, suggesting that the hair may have been introduced from outside the cyst. Pilonidal disease was a common problem among servicemen during World War II, thought to be due to the mechanical trauma of riding in jeeps, trucks, and tanks.