Definition of Pilonidal Disease

pilonidal diseasePilonidal Disease is a chronic condition in which hair-filled cysts form at the base of the spine.

The cysts typically originate when the skin closes to form saclike structures with hair trapped inside.

The sac fills with fluid, cells, and other debris. Often there are indentations or pits over the tops of the cysts, and sometimes the hair within the cyst protrudes out.

Pilonidal cysts often remain symptomless, though many become apparent because they are subject to persistent irritation from clothing, movement, and pressure. Extended sitting, clothes that fit tightly across the buttocks, and activities such as bicycling often create awareness of pilonidal cysts.


The key symptoms of pilonidal disease are pain, swelling, erythema (redness), and drainage (pus) over the sacrum (tailbone). Often a fever accompanies these symptoms, and the person is unable to sit or walk without great discomfort.

The doctor often can diagnose pilonidal disease based on the appearance of the cysts and the history of the symptoms. The doctor typically lances (cuts open with a sterile instrument) the cysts to allow them to drain. Large, purulent, or recurrent cysts may require surgery to remove them.


Pilonidal disease tends to be recurrent and persistent, often continuing throughout life. Surgically removed cysts seldom return, though new cysts frequently form in the same proximity. Keeping the area clean and wearing loose-fitting clothing can help prevent pilonidal cysts from becoming irritated.

Frequent position changes when sitting and sitz baths (sitting in warm water) help reduce discomfort when cysts are present.


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