Definition and Overview

Pilonidal cysts are abnormal sacs or lumps that develop at the top of the buttocks crease or the base of the spine. They appear as swollen papules or nodules and are usually filled with hair and skin cells. If the cysts become infected and form an abscess, a sinus tract (pilonidal sinus) may develop from the source of infection and open to the surface of the skin, where pus and other materials drain. Uninfected pilonidal cysts are typically symptoms-free while those that have been infected usually cause pain, swelling, draining of blood or pus, and a foul smell.

The condition is not serious and rarely a medical emergency. However, treatment is usually advised because the cyst can enlarge and cause significant discomfort when a person sits or put pressure on it. Depending on the severity of the condition, it can be adequately managed by draining the pus or through surgery that removes all infected tissue and sinus tracts.

Anybody of any age and gender can develop pilonidal cysts. Some babies are born with a skin dimple at the base of their spine, which can develop into a cyst if infected. However, the condition is more common in males and people in their 20s.

Causes of Condition

The exact reason why pilonidal cysts develop is not known. However, there is a theory suggesting that certain activities, such as prolonged sitting, can force the hair growing in the area to burrow back into the skin. If pressure or friction (which can be caused by wearing tight clothing and/or prolonged sitting) causes the loose hair to work itself down into the skin, the immune system will react as if a foreign object has invaded the body. This theory may explain why the condition is more common in people whose jobs require them to sit for an extended period (such as truck and taxi drivers) and why pilonidal cysts typically contain hair.

Certain factors that can increase one’s risk of developing pilonidal cysts include:

  • Obesity

  • Trauma to the base of the spine

  • Excess body hair

  • Family or personal history of pilonidal cysts

  • Being male - Men are four times more likely to develop the condition than women

  • Sedentary lifestyle

  • Poor hygiene

  • Prolonged sitting, especially when slouching

Key Symptoms

Often, pilonidal cysts do not cause any symptoms, particularly during the early stages and if they are not infected. Other than the presence of a small lump in between the upper part of the buttocks cheeks, patients usually have nothing more to complain. However, when the cyst becomes infected, the following are usually observed:

  • Pain or discomfort that seems to intensify when a person is sitting down, riding a bike, or doing certain exercises like sit-ups

  • Reddening of the skin

  • Swelling

  • Drainage of pus and blood

  • A foul odour

  • Hair protruding from the cyst

  • Warm skin

  • Fever (very rare)

  • Moisture in the tailbone region

  • Fistula – An abnormal sinus tract or channel that opens to the surface of the skin

Who to See and Types of Treatments Available

Pilonidal cysts are diagnosed through a physical examination. Through this exam, experienced doctors are able to differentiate it from other types of cysts that share the same appearance, such as dermoid cysts and sacrococcygeal teratoma. The ability to distinguish a pilonidal cyst from other cysts is important as each type requires a different method of treatment. A blood test may also be performed if the cyst is infected.

The goal of pilonidal cyst treatment is to remove all cystic tissue (to prevent recurrence) and ensure the healing of healthy tissue. Infected pilonidal cysts with abscess are treated with antibiotics before they are cut open so the pus can be drained (incision and drainage). Once the infection has cleared, the patient may undergo pilonidal cystectomy.

For the procedure, the doctor may use an electrically heated needle or other instruments to remove infected tissue and sinus tracts as well as approximately 0.2 cm of surrounding healthy tissue. The walls of the wound are also debrided with curettage. The doctor may also opt to sew the edges of the wound to minimise the amount of exposed tissue.

In most cases, the wound is left open to allow it to heal on its own. Although this technique shortens surgery time and minimises the risk of occurrence, it prolongs healing times and may cause inconvenience because it requires daily dressing changes.

To hasten recovery, a negative pressure wound therapy device can be used to make the wound heal faster, reduce the bacterial load, and provide local debridement with each dressing change.

A cystectomy can involve closing the wound with sutures. If the wound is deep, it will be closed in layers using absorbable sutures.

Although proven effective, pilonidal cystectomy has risks and possible complications such as delayed wound healing. If the wound has been closed but has not healed as expected, the patient has to undergo another procedure to treat the infection. Other risks include pain, especially for patients whose wounds are left open and have to change dressings on a daily basis. The condition can also recur even after successful treatment.


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  • Mentes O, Bagci M, Bilgin T, Coskun I, Ozgul O, Ozdemir M. Management of pilonidal sinus disease with oblique excision and primary closure: results of 493 patients. Dis Colon Rectum. 2006 Jan. 49(1):104-8.

  • Favuzza J, Brand M, Francescatti A, Orkin B. Cleft lift procedure for pilonidal disease: technique and perioperative management. Tech Coloproctol. 2015 Aug. 19 (8):477-82.

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