Pilonidal Sinus

Pilonidal sinus—also called a pilonidal cyst—is a skin infection that occurs in or around the crease of your buttocks. This condition happens when hair, skin cells, and dirt clog a hair follicle, creating a sinus tract (a small tunnel in the skin) that can become infected and turn into a cyst or swollen lump of tissue. 

Many people find a pilonidal sinus forming in an area somewhere between their coccyx (tailbone) and anus. While seeing or feeling a cyst can seem worrisome, pilonidal sinus is a benign (noncancerous) condition. However, the condition can cause pain or swelling and may require surgery in severe cases.

Pilonidal Sinus Symptoms 

Pilonidal sinus symptoms can range in severity. Some people may experience mild or barely noticeable symptoms, while others have symptoms that are severe enough to interfere with daily activities. If you develop this infection, you may notice these common symptoms:

• A small dimple, pit, or cyst in the skin
• Tenderness when sitting or standing for long periods
• Redness, swelling, warmth, or pain in the buttocks
• Pus draining from a lump or hole in the skin that may smell foul
• Fever or flu-like symptoms

You may realize you have a pilonidal sinus before an abscess or growth develops. Still, many people contact their healthcare provider when the sinus cavity suddenly becomes infected, creating a lump of swollen tissue.

Causes

Normally, your body hair grows in the area above and between the buttocks, but when the hair from one or more follicles grows into the skin, it can result in ingrown hair. Essentially, the hair grows inward instead of outward, increasing the risk of infection.

It’s not fully understood why this infection happens more often in some people or why ingrown hairs in the area of the buttocks can cause sinus tracts to form. However, some researchers believe that pilonidal sinus results from a combination of three factors:

• Ingrown hair
• An area of vulnerable skin
• Some type of pressure that pushes the hair deep enough into the skin to form a sinus tract

Risk Factors

While anyone can get a pilonidal sinus, some factors can increase your risk, including:

• Being assigned male at birth
• Having a family history of pilonidal sinus
• Being of younger age, generally between adolescence and 40 years older
• Living with obesity
• Experiencing trauma or injury to the coccyx or buttocks
• Sitting often or not moving around throughout the day
• Having thick, curly, or coarse hair

Diagnosis

If you think you may have a pilonidal sinus, seeing a healthcare provider can help you get started on treatment sooner and relieve discomfort sooner. At your appointment, your provider will ask about your medical history and perform a physical exam. The physical exam is enough to receive a diagnosis and you won't need additional testing unless your provider thinks you have another condition.

Pilonidal Sinus Treatment 

It's worth noting that if a pilonidal sinus isn't causing any symptoms, you may not need any treatment. However, if you require treatment, the goals are to eliminate the infection, relieve discomfort, and prevent future cysts. Everyone's treatment plan varies, but your provider will likely recommend nonsurgical treatments, then move on to surgical measures (or a combination of both) if your symptoms don't improve.

Before starting treatment, your provider will assess if your cyst is infected. If you have a pus-filled cyst (known as an abscess), your provider will likely numb the area with a local anesthetic, make a small incision (cut), and drain the pus from the cyst. Then, they can offer treatment options to heal the cyst and treat the sinus tract.

Nonsurgical Treatments

For a pilonidal sinus that isn't infected, your provider may recommend nonsurgical treatments to reduce the sinus tract and prevent inflammation. These methods include:

• Hair removal: Since ingrown hairs cause pilonidal sinus, hair removal techniques (e.g., waxing, shaving, and laser treatments) can be used to remove them.
• Medications: Several medications can treat pilonidal sinus. The first treatments might include oral and/or topical antibiotics, antiseptic washes, or corticosteroid injections into the sinus. More intensive treatments might include Phenol (an antiseptic and disinfecting medicine), which can chemically scar the tissue inside the tract to prevent further growth, Tisseel (fibrin glue), which can close up and seal the sinus tract, and a platelet-rich plasma injection which can encourage quick wound healing.

Surgical Treatments

If you have chronic or recurring infections because of your pilonidal sinus, your provider may recommend that you have a surgical procedure to remove or close the sinus tract and prevent future problems. There are many different surgical approaches your provider may consider:

• Excision: Surgically removing the sinus tract and any inflamed tissue surrounding the cyst
• Unroofing: Opening up an abscess to drain and clean the tissue
• Flap closure: Attaching a skin graft or flap to the opening of the sinus tract to close off the tract and prevent future inflammation and hair regrowth
• Ablation: Inserting a tool into the sinus tract to clean out hair and debris and then destroying the affected tissue

How To Prevent Pilonidal Sinus

If you’re at a higher risk of developing a pilonidal sinus because of your age or sex, it may be difficult to prevent this condition. But many risk factors of this infection are environmental, so there may be some things you can do to reduce your risk of developing one:

• Avoid prolonged sitting and taking stretch or walking breaks throughout the day
• Managing obesity by getting regular physical activity and eating nutritious foods
• Cleaning and exfoliating the skin around your buttocks regularly
• Avoid clothing with rough seams, like denim, that could contribute to rubbing or chaffing in the affected area.

Complications 

If left untreated, pilonidal sinus can cause more severe infections or abscesses. The most common complication is the infection recurring. Sometimes, this can also happen even if you receive treatment. But, getting early treatment and following proper hygiene techniques can limit your risk of having this infection again and experiencing complications.

A Quick Review

Pilonidal sinus is a skin infection that causes a cyst near the buttocks, just beneath the tailbone. The infection often occurs when an ingrown hair grows internally and infects the skin. As a result of the infection, symptoms like pain, swelling, and a pus-filled bump can develop. Fortunately, treatment is available to reduce symptoms. Your provider may recommend medications, hair removal, and surgical methods to clean out the infection and prevent further inflammation.