Pilonidal Sinus

What is pilonidal sinus disease?
Pilonidal sinus disease is a chronic infection of the skin usually in the region of the natal cleft (buttock crease). The condition results from a reaction to hairs embedded in the skin and is more common in men than women. It frequently occurs between puberty and age 40.

What causes pilonidal sinus disease?
The exact cause is not clear. There are various theories. One theory is that the problem may develop from a minor congenital abnormality in the skin of the natal cleft. Part of the abnormality in this part of the skin may be that the hairs grow into the skin rather than outwards. Another theory is that skin pits develop in the skin between the buttocks. These may develop from damaged hair follicles (the small structures under the skin that make the hairs) due to local pressure or friction. Because of local pressure, growing hair in the natal cleft may get pushed into these skin pits. Once hair fragments become stuck, they irritate the skin and cause inflammation. This can lead to a persistent infection in the affected area. The infection causes the sinus to develop which often contains broken pieces of hair.

What are the symptoms?
Symptoms vary from a visible small skin opening (or dimple) to a large painful lump in the natal cleft. Often the area will drain fluid that may be clear, cloudy or bloody. Many patients have an episode of an acute pilonidal abscess (the area is tender, swollen and may drain pus). After the abscess resolves (either by spontaneously discharging or following surgical drainage) many patients have a persistent pilonidal sinus. The sinus is a cavity below the skin surface that connects to the surface with one or more openings or tracts under the skin. Some patients develop recurrent infections and inflammation of these sinus tracts with many episodes of swelling, pain and purulent discharge. Surgery is required to resolve this condition.

How is pilonidal sinus disease treated?
An acute pilonidal abscess is managed by incision and drainage to release the pus and reduce the inflammation and pain. A chronic sinus usually will need to be surgically excised. Complex or recurrent disease must be treated surgically. Pilonidal sinus disease is a difficult condition to treat with complete success, so many different surgical procedures have been described in the medical literature over the years, each with varying success rates. Procedures vary from simple de-roofing the sinuses to wide local excision with or without primary (i.e. at the time of initial surgery) closure of the skin. If the wound is left open, healing may take weeks or months and will require daily dressing or packing to keep it clean. This may require many weeks away from work. Wide excision of the diseased area with closure using heavy sutures is painful and associated with a high rate of wound breakdown as the sutures are usually under tension. Questions to ask your surgeon include what type of procedure they commonly undertake, post-operative pain levels, expected healing times and recurrence rate.

The best procedures avoid leaving a large open wound, avoid tension in the midline and preferably bring healthy tissue into the area that has been excised. Wide excision and closure using a local skin flap (such as a Limberg Flap) has a very high success rate with a very low (<5%) risk of recurrent sinus formation. The operation usually takes a little longer than many of the more commonly performed procedures for pilonidal sinus and usually requires a short spell in hospital but post-operatively there is surprisingly little discomfort (as the sutures are not placed under tension) and work can be resumed without the need for long term dressings.

View Mr Tsavellas performing a Limberg Flap for Pilonidal Sinus Disease

Private Hospitals