Pilonidal Cyst: Symptoms & Signs

Medically Reviewed on 11/9/2020

A pilonidal cyst is a sac filled with hair and skin debris that forms at the top of the crease of the buttocks above the sacrum (lower part of the spine). The cyst may form an abscess, and the skin overlying the cyst may become infected if this occurs.

Signs and symptoms of a pilonidal cyst can include a

  • lump or bump at the upper middle of the buttocks,
  • pain,
  • reddening of the skin, and
  • drainage of pus or blood from an opening in the skin.

Other associated symptoms can include a foul smell from draining pus.

Cause of a pilonidal cyst

The trapping of hair and debris in the pores of the skin in the upper cleft of the buttock causes pilonidal cysts. They are more common in those who are obese and sedentary, and they are more common in males than in females.

Other pilonidal cyst symptoms and signs

  • Foul Smell from Draining Pus
  • Drainage of Pus or Blood from an Opening in the Skin
  • Lump or Bump at the Upper Middle of the Buttocks
  • Pain
  • Reddening of the Skin


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Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.