by Polsdorfer R
(Pilonidal Sinus; Pilonidal Abscess)


A pilonidal cyst is a fluid-filled developmental defect at the base of the spine.

The terms cyst, sinus, and abscess refer to different stages of the disease process.

  • Cyst—not infected
  • Abscess—pocket of pus
  • Sinus—opening between a cyst or other internal structure and the outside

While the cyst is not serious, it can become infected and may need to be treated if problems develop. When a pilonidal cyst gets infected, it forms an abscess, eventually draining pus through a sinus.

Pilonidal Cysts
Pilonidal cyst
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A pilonidal cyst may be congenital or acquired. If congenital, it probably began as a defect that existed at birth. Sometime later, the defect allowed an infection to develop. If acquired, it may be the enlargement of a simple hair follicle infection or the result of a hair penetrating the skin and causing an infection.

Risk Factors

The following factors increase your chance of developing a pilonidal cyst:

  • Personal or family history of pilonidal disease
  • Large amounts of hair in the region
  • Midline skin pits or deep gluteal cleft
  • Tailbone irritation or injury
  • Continuous bouncing in seated position, such as horseback riding or cycling
  • Prolonged sitting
  • Obesity


A pilonidal cyst may cause:

  • Painful swelling over your sacrum, which is the area just above your tailbone
  • A foul smell or pus draining from that area


You will be asked about your symptoms and medical history. A physical exam will be done. You may be referred to a surgeon for treatment. There are no diagnostic tests required.


Talk with your doctor about the best treatment plan for you. The choice of treatment will depend on the extent of the condition and your general overall health. Treatment options include:

Home Treatment

As with all localized infections under the skin, warm water soaks will draw out the infection. This will not completely cure the condition, but it will help.

Incision and Drainage

The abscess is lanced, the pus drained, and the wound is packed with sterile gauze. This helps it heal from the inside out. This usually does not cure the problem because abnormal tissue remains.


To completely cure the condition, all affected tissue needs to be removed. It may be considered if you have repeated infections. This is a more extensive surgical procedure than simple incision and drainage. The surgical wound may be closed with sutures or left open to heal from the inside.


To help reduce your chances of a pilonidal abscess:

  • Keep the area clean and dry
  • Avoid sitting for a long time on hard surfaces
  • Remove hair from the area
  • Talk to your doctor about laser hair removal


American Society of Colon and Rectal Surgeons 

Family Doctor—American Academy of Family Physicians 


HealthLink BC 

The College of Family Physicians of Canada 


Pilonidal cyst. Family Doctor—American Academy of Family Physicians website. Available at: Updated April 2014. Accessed August 18, 2017.

Pilonidal cyst. Swedish Medical Center Seattle website. Available at: Accessed August 18, 2017.

Pilonidal disease. EBSCO DynaMed Plus website. Available at:  . Updated January 30, 2017. Accessed August 18, 2017.

Pilonidal sinus and cysts. Children's Hospital of Philadelphia website. Available at: Accessed August 18, 2017.

Sadick NS, Yee-Levin J. Laser and light treatments for pilonidal cysts. Cutis. 2006;78(2):125-128.

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