What Is a Pilonidal Cyst?

A pilonidal cyst, which might sometimes be called pilonidal disease, is a fluid-filled sac that usually occurs on the tailbone at the top of the buttocks.

The cyst can become infected and form an abscess (a pocket of infection) that progresses to a fistula (an abnormal connection between two organs or an organ and the skin). It usually starts as an infection of a hair follicle in the area.

This article will discuss the possible symptoms, causes, and treatments for pilonidal cyst.

Types of Pilonidal Cyst

A pilonidal cyst can be acute (comes on quickly) or chronic (lasts a long time and resists treatment). 

In the acute form, you may have an abscess in the natal cleft, the area at the top of the buttocks where they part. The abscess might cause pain and swelling. 

In the chronic form, fluid may come from the cyst. The fluid might be constant or only happen from time to time, The fluid could be watery and thin, or it could be thicker and milky.

Chronic pilonidal cysts can be difficult to treat and come and go for many years. This might be termed "pilonidal sinus disease," meaning the condition is more serious.

Pilonidal Cyst Symptoms

It’s possible that a pilonidal cyst might not cause any symptoms. In these cases, the cyst might be found incidentally, meaning it’s first noticed before it causes any symptoms.

A pilonidal cyst may cause symptoms, especially if it becomes infected. Some of the symptoms might include:

• A painful lump at the bottom of the spine/top of the buttocks
• An area that feels hot to the touch
• Discharge (fluid leaking from the area)
• Redness and swelling (erythema)
  

Causes

Pilonidal cysts are still somewhat misunderstood, even though the condition was first defined in 1833.

Usually, a pilonidal cyst starts with a hair that somehow makes its way into the skin. This hair might then embed deeper into the skin because of friction or pressure.

Hormones might contribute to the hair follicles becoming larger, which may cause some of the glands in the area to become blocked. Eventually, a cyst forms around the hair.

Some risk factors for a pilonidal cyst include being male, being younger than 40, having lots of hair in the area, and having a deep split between the buttocks (natal cleft). Sitting for long periods, not keeping the area clean, and having obesity are also thought to contribute to developing a pilonidal cyst.

Pilonidal cysts are more common in males than females. They are especially found in teens and young males until their early 30s. (Note that Verywell Health prefers to use inclusive terminology. But when citing research papers, the terms for sex and gender from those sources are used.)

Diagnosis

A pilonidal cyst is usually diagnosed by examining the area of the natal cleft for a cyst. Other symptoms like redness, swelling, and pain will also be major clues in the diagnosis.

Tests like an ultrasound an endoscopy (using a flexible tube with a camera to see inside the body), a computed tomography (CT) scan, and magnetic resonance imaging (MRI) are usually not needed to diagnose a pilonidal cyst. These tests or others might be used if the cyst is thought to be related to or caused by another condition.

If the cyst is in an unusual location or has other features that don’t seem related to a cyst, other diagnoses might be considered.

Treatment

Treatment for a pilonidal cyst is usually first draining it or having surgery to remove it. There are several different procedures that might be used. However, there’s no agreement on which type of surgical procedure might be the most effective.

A healthcare provider may first drain the cyst in the office. This would be done with a local anesthetic, meaning that the area around the cyst is numbed with an injection. The cyst can then be opened with an incision and drained of any fluid it contains.

If the cyst recurs or there are other complications, a more invasive surgery might be done. In these types of surgery, the cyst might be removed.

The size of the incision and how much of the skin and tissue is removed will vary depending on the type of procedure. In some cases, if the surgery is more extensive, there could be a need for general anesthesia and being hospitalized.

Surgery might include using antibiotics (oral or topical) to avoid infection. There also might be a dressing on the area that needs to be changed. In all cases, follow-up care will be needed to check on the healing.

Prognosis

A pilonidal cyst is considered a benign (usually harmless) condition but can be painful and recur, causing problems on and off. Rarely, it could lead to a serious infection or complication if not treated.

The more conservative treatments for pilonidal cysts, such as drainage, are unfortunately associated with recurrence. The cyst might come back in between 10% and 20% of cases. The more invasive surgical options can have a recurrence rate of between 1% and 11%.

Less invasive treatment methods might be used first because they are easier on the person being treated, including being less painful and causing them to lose fewer days from work. With the more invasive treatments, you have a lower risk of the cyst returning, though.

Pilonidal cysts are less common in people over the age of 40. For that reason, they might stop being a problem as people age.

Coping

A pilonidal cyst can be painful, embarrassing, and affect your quality of life. The condition needs treatment to avoid it from becoming infected and causing more serious disease.

It’s important to ask questions when getting treated for a pilonidal cyst. With shared decision-making, you should be told what options are available for treatment and the potential complications. 

Because pilonidal cysts develop near the buttocks, they can cause shame and embarrassment. Remember that healthcare providers see these types of conditions all the time.

There will be a need to care for the surgical location at home. It may help to have a partner assist or see if a home-care nurse is available.

Studies have been done on the benefits of removing hair in the area to reduce the risk of recurrence. The evidence that permanent hair removal might help lower the risk of a cyst returning is considered weak.

It’s also unclear if shaving the area might increase the risk of a recurrence. For that reason, permanent hair removal might be considered, but the method that would be best isn’t yet understood.

Summary

Pilonidal cysts are fluid-filled sacs that develop on the tailbone at the top of the buttocks. They are associated with hair follicles and happen more often in young males.

These cysts should be diagnosed and treated by a healthcare professional, preferably one with experience in surgical treatments for this condition. Caring for the area after treatment is important. Any problems should be evaluated right away.

A Word From Verywell

Pilonidal cysts are not uncommon, and they can also cause pretty significant pain and be a burden. They do need to be treated by a healthcare provider since they likely won’t go away on their own.

Most of the time, they can be treated effectively and won’t come back. However, they can become chronic, so it’s important to get treatment right away and to follow up with your healthcare provider.