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Symptoms and Signs of Pilonidal Cyst

Doctor's Notes on Pilonidal Cyst

A pilot cyst is a structure that develops along the tailbone at or near the cleft of the buttocks and rarely elsewhere on the body. Signs and symptoms include pain over the lower spine, skin redness, warmth and swelling with drainage of pus; a few patients may develop fevers.

Most researchers think that pilonidal cysts are caused by penetration of loose hairs into the skin (ingrown hairs) along with skin debris. Repetitive pressure and/or trauma to the lower back is thought to increase the development or even cause pilonidal cysts.

Medical Author:
Medically Reviewed on 3/11/2019

Pilonidal Cyst Symptoms

As previously mentioned, some individuals with a pilonidal cyst may be asymptomatic, and the only finding may be a dimple or an opening in the skin (sinus tract) in the sacrococcygeal area. However, if the pilonidal cyst becomes infected, the following signs and symptoms may develop:

  • Pain over the lower spine
  • Redness of the skin
  • Warmth of the skin
  • Localized swelling over the lower spine
  • Drainage of pus from an opening in the skin (sinus tract) over the lower spine
  • Fever (uncommon)

Less commonly, pilonidal cysts can develop in other areas of the body such as the hands.

Pilonidal Cyst Causes

Although there are several theories as to the causes and origins of pilonidal disease, most researchers today believe that pilonidal cysts are acquired (rather than congenital, or inborn) and that they are caused by the penetration of loose hairs into the skin through dilated hair follicles into the subcutaneous tissues. In response to this ingrown hair, a local inflammatory reaction causes a cystic structure to form around the hair and the other skin debris. Excessive pressure or repetitive trauma to the sacrococcygeal area are thought to predispose individuals to develop the cyst or to irritate an already existing pilonidal cyst.

During World War II, more than 80,000 U.S. soldiers developed pilonidal cysts requiring hospitalization. Because so many of the afflicted servicemen rode in bumpy Jeeps for prolonged periods of time, the condition was termed "Jeep disease." It was during this time that many investigators produced articles on the treatment and management of pilonidal disease.

In addition to male gender, other risk factors for the development of pilonidal cysts include a family history of pilonidal cysts, occupations which require prolonged sitting, hirsute (hairy or having copious hair) individuals, and the presence of a deep natal cleft (the cleft between the buttocks). Obese individuals are more likely to experience a recurrence of pilonidal cysts.

Boils Causes, Symptoms, and Home Remedies Slideshow

Boils Causes, Symptoms, and Home Remedies Slideshow

A boil is caused by a bacterial skin infection. This skin abscess forms deep inside a hair follicle or oil gland. A boil generally starts as a reddened, tender area. Over time, the area becomes firm and hard.

The infection damages your skin cells, hollowing the tissue out. Your immune system responds with white blood cells, which fill the center of the infection and make it soft. Your body makes these cells to destroy the infection.

Together with bacteria and proteins, these white blood cells are known as pus. This pus may eventually form a central head near the surface of your skin. This head may drain on its own, spilling out of the surface of your skin. If not, it can be surgically opened.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.