Pilonidal cyst

A pilonidal cyst is a pocket of skin found at the base of the spine, slightly above the crease of the buttocks. The cyst usually looks like a small depression in the skin and may have a few hairs sticking out of it.


Causes/associated factors
The exact cause of pilonidal cysts isn't well understood. They seem to develop when hair follicles in the lower spine become enlarged. Bacteria can enter the enlarged follicle, entrap hair, and cause irritation and infection. Friction in the lower spinal area -- as you may experience with long, bumpy car or lawnmower rides -- can encourage the process. Males in their teens to early 40s are the most likely to develop pilonidal cysts.
Other risk factors include:

heavy growth of body hair, especially in the lower spinal area
genetic predisposition to the condition
obesity
sedentary lifestyle
repeated trauma to the area
sitting for long periods of time
perspiration
tight clothing
being Caucasian

Signs/symptoms
Unless they're inflamed or infected, pilonidal cysts usually have few or no symptoms. Signs of an inflamed or infected cyst include:
pain
redness and warmth
swelling
fever
pus discharge

Diagnosis
Diagnosis is based on your medical history, current symptoms and a physical exam. In some cases, you may also need lab tests.

Treatment
Treatment depends on the symptoms. If the cyst isn't infected and doesn't bother you, your doctor may tell you to simply watch the area and keep it very clean. If the cyst becomes infected, you may need an incision and drainage -- a minor surgical procedure to open the cyst and remove the infectious matter inside. The area will be packed with sterile gauze and allowed to heal slowly. If you develop recurrent infections, the entire affected area may need to be surgically removed. This procedure is more involved and has a longer healing period.

Complications
Depending on your occupation, pilonidal cysts may hamper your ability to work. A cyst may lead to the formation of long-draining sinus tracts. Very rarely, a cyst may become malignant (cancerous).

Pregnancy-specific information
Pregnancy isn't a risk factor for pilonidal cysts.

Senior-specific information
Growing older isn't a risk factor for this condition.

Prevention
To prevent pilonidal cysts, keep these suggestions in mind:
Maintain an ideal body weight.
Take a daily bath (not shower) to keep the lower spinal area clean.
Shave the area periodically.
Wear loose-fitting clothing.
Avoid activities that may irritate the lower spine, such as prolonged sitting.