What is pilonidal disease and what causes it?

Pilonidal disease is a chronic infection of the skin in the region of the buttock crease (Figure 1). The condition results from a reaction to hairs embedded in the skin, commonly occurring in the cleft between the buttocks. The disease is more common in men than women and frequently occurs between puberty and age 40. It is also common in obese people and those with thick, stiff body hair.

Figure 1: Pilonidal disease is a chronic skin infection in the buttock crease area. Two small openings are shown (A).

What are the symptoms?

Symptoms vary from a small dimple to a large painful mass. Often the area will drain fluid that may be clear, cloudy or bloody. With infection, the area becomes red, tender, and the drainage (pus) will have a foul odor. The infection may also cause fever, malaise, or nausea.

There are several common patterns of this disease. Nearly all patients have an episode of an acute abscess (the area is swollen, tender, and may drain pus). After the abscess resolves, either by itself or with medical assistance, many patients develop a pilonidal sinus. The sinus is a cavity below the skin surface that connects to the surface with one or more small openings or tracts. Although a few of these sinus tracts may resolve without therapy, most patients need a small operation to eliminate them.

A small number of patients develop recurrent infections and inflammation of these sinus tracts. The chronic disease causes episodes of swelling, pain, and drainage. Surgery is almost always required to resolve this condition.

How is pilonidal disease treated?

The treatment depends on the disease pattern. An acute abscess is managed with an incision and drained to release the pus, and reduce the inflammation and pain. This procedure usually can be performed in the office with local anesthesia. A chronic sinus usually will need to be excised or surgically opened.

Complex or recurrent disease must be treated surgically. Procedures vary from unroofing the sinuses to excision (Figure 2) and possible closure with flaps. Larger operations require longer healing times. If the wound is left open, it will require dressing or packing to keep it clean. Although it may take several weeks to heal, the success rate with open wounds is higher. Closure with flaps is a bigger operation that has a higher chance of infection; however, it may be required in some patients. Your surgeon will discuss these options with you and help you select the appropriate operation.

Figure 2: Drawing B is a side view showing how most of the inflammation is deep under the skin just outside the coccyx (tailbone). The dashed line shows how it may be opened or unroofed. Dashed line in drawing C shows excision of all inflamed tissue.

What care is required after surgery?

If the wound can be closed, it will need to be kept clean and dry until the skin is completely healed. If the wound must be left open, dressings or packing will be needed to help remove secretions and to allow the wound to heal from the bottom up.

After healing, the skin in the buttocks crease must be kept clean and free of hair. This is accomplished by shaving or using a hair removal agent every two or three weeks until age 30. After age 30, the hair shaft thins, becomes softer and the buttock cleft becomes less deep.

Reference: American Society of Colon and Rectal Surgeons