Have you ever had an ingrown hair that seemed to grow beneath the surface? Well, that is the same process that sometimes leads to a condition called a pilonidal (PIE-low-NI-dal) cyst. Pilonidal disease develops when a dead hair is pushed into tiny abrasions or scars in the skin. (In fact, the term pilonidal meaning "nest of hair" was coined in 1830.) As the hair grows into the skin, it forms a small one-ended tunnel beneath the surface. Germs can grow in this tunnel, causing it to become infected. If the opening to the skin becomes blocked, painful swelling occurs, much like a boil.
Where does this happen?
The typical location for a pilonidal cyst to form is the skin over the tailbone, just above the cleft of the buttocks. This embarrassing location is chosen not only because of the hair and bacteria there, but especially because of the friction and pressure on the area that can push hairs into the skin when the person is sitting. A pilonidal cyst does not turn to cancer, but may cause painful symptoms. Rarely, serious infection may result.
Who gets pilonidal cysts?
Pilonidal cysts tend to occur in young men since they usually have more body hair, although it can occur in anyone. In a population study of Minnesota college students, pilonidal cysts were found at routine physical exams in 1.1% of males and 0.11% of females. It usually occurs after puberty and is rarely seen after age 40. Incidence is highest in whites and less in Africans and Asians, perhaps due to differences in hair characteristics. Pilonidal cysts are more common in obese people, those with sedentary jobs, and those with thick, stiff body hair. Heavy perspiration and tight clothing may also be risk factors.
What are the symptoms?
Symptoms vary from a small pimple to a large painful mass. Often the patient will notice fluid draining from the area and staining their underwear. Often, the wife sees her husband's stained shorts in the laundry basket and insists he see the doctor. If infection occurs, the area becomes red, tender, and the drainage (pus) will have a foul odor. An infected pilonidal cyst is called an acute abscess and can be very painful. These patients seek medical attention immediately complaining of a very tender spot right between the buttocks. The pain may be so bad that it may be difficult to sit or walk.
After an acute abscess resolves, either by itself or with treatment, patients may develop a sinus tract. A sinus tract is a cavity below the skin surface that connects to the surface with one or more small openings. Although a few of these sinus tracts may resolve without therapy, most patients need an operation to eliminate them. If repeated infections occur, surgery is almost always required to resolve this condition.
How does your doctor know?
Your doctor will make the diagnosis of pilonidal cyst based on your symptoms and his examination of the area. He may see a small, hair-containing skin sac at the base of the spine. The cyst looks like a small opening--sometimes no more than a dimple--with a few hairs protruding. He may need to probe the area and sometimes will obtain samples of the drainage to search for infection. Infection is usually caused by staphylococcal bacteria. It is important to rule out other conditions that may mimic a pilonidal cyst such as a perirectal abscess or anal disease.
The treatment depends on the symptoms. Minor cysts with no symptoms may need no therapy. There is no role for dietary therapy or restriction of daily activities. If a cyst is painful, soaking in a warm tub baths may help relieve the pain. An acute abscess is usually drained by making a small skin incision with a scalpel which releases the pus, reduces the pain, and allows healing. This procedure usually can be performed in the office with local anesthesia. Antibiotics are not the primary mode of treatment, but may supplement surgical drainage.
Unfortunately, 40% of patients return with recurrence of their disease after primary treatment. A chronic sinus or recurrent disease will need to be treated surgically. Depending on the situation, procedures vary. Sometimes the cyst is "unroofed" and the wound left open to heal. In this case, daily wound dressing or packing is needed to keep it clean to allow it to heal from the inside out. Although it may take up to two months to heal, the long-term success rate with open wounds is higher. A wide excision of the cyst and closing the wound with skin flaps is a bigger operation and has a higher chance of infection; however, it may be required in some patients. Your surgeon can best decide which is best.
Uncommon after age 40
Fortunately, after age 40, pilonidal cysts tend not to return. Until then, patient with a history of pilonidal cysts should keep the skin in the buttocks crease clean and free of hair. This is accomplished by shaving or using a hair removal agent every three to four weeks. Loose-fitting clothing is best and excess weight should be lost.