Pilonidal Cyst Causes, Symptoms, and Signs

  • Medical Author:
    Steven Doerr, MD

    Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Pilonidal cysts facts

  • Pilonidal cysts occur along the tailbone near the cleft of the buttocks.
  • Pilonidal cysts are thought to develop from the penetration of hairs deep into the skin.
  • Pilonidal cysts can become infected.
  • An infected pilonidal cyst (pilonidal abscess) requires incision and drainage.
  • Recurrence of pilonidal cysts is common, and surgery may be required for more definitive management.

What is a pilonidal cyst?

A pilonidal cyst is a fluid-filled sac (cyst) that develops along the tailbone (coccyx) near the cleft of the buttocks. These cysts usually contain hair and skin debris, and sinus tracts may develop. Some individuals with a pilonidal cyst or sinus may not have any symptoms at all, whereas others may develop an inflammation of the cyst that leads to abscess formation with associated pain, redness, and irritation. Despite treatment, recurrence of pilonidal cysts is common.

Pilonidal disease was first described by Herbert Mayo in 1833, with R.M. Hodge coining the term pilonidal in 1880 from the Latin words pilus (hair) and nidus (nest). Extensive work into the treatment and management of pilonidal disease occurred during World War II, when nearly 80,000 U.S. soldiers were treated in U.S. military hospitals for this condition between 1941-1945. Because so many of the affected servicemen rode in Jeeps for prolonged periods of time, the condition also became known as "Jeep disease."

What causes a pilonidal cyst?

Though there are several theories as to the cause of pilonidal disease, most researchers now believe that pilonidal disease is acquired (rather than congenital) and that it is caused by the penetration of hair into deeper subcutaneous tissues through dilated hair follicles in the skin. In response to this irritation and perceived foreign material, the body produces a local inflammatory reaction, causing a cyst to form around the trapped hair. Excessive pressure, friction, and repetitive trauma to the sacrococcygeal area are thought to facilitate the entry of hair, thus predisposing individuals to develop pilonidal disease or irritate already existing pilonidal cysts.

Who is at risk for developing a pilonidal cyst?

The incidence of pilonidal disease is approximately 26 cases per 100,000 people. Pilonidal disease generally occurs in people between the ages of 15-24, and it is very uncommon in individuals over the age of 40. Males are more frequently affected than females, and it is more common in white individuals. Other risk factors associated with the development of pilonidal disease include a family history of pilonidal cysts, occupations that require prolonged periods of sitting, local trauma, obesity, hirsute (hairy or having copious hair) individuals, and the presence of a deep cleft between the buttocks.

What are the signs and symptoms of a pilonidal cyst?

Certain individuals with a pilonidal cyst may not have any symptoms at all, and the only finding may be a dimple or an opening in the skin (sinus tract) near the cleft of the buttocks. However, if the pilonidal cyst becomes infected (pilonidal abscess), 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)

Though much less common, pilonidal cysts can also develop in other areas of the body, such as the hands.

Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine


de Caestecker, James. "Pilonidal Disease." Medscape.com. Aug. 24, 2009. <http://emedicine.medscape.com/article/192668-overview>.

Lanigan, Michael D. "Pilonidal Cyst and Sinus." Medscape.com. Aug. 6, 2009. <http://emedicine.medscape.com/article/788127-overview>.

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