Pilonidal disease is a chronic infection of the skin in the region of the buttock crease. It results from hairs being embedded in the skin, commonly occurring in the cleft between the buttocks. It is more common in men, in obese people and those with thick, stiff body hair.

Symptoms vary from a small dimple to a large painful mass. There may be a discharge that is clear, cloudy or bloody. When infected, the area becomes red and painful. There may also be fever.

Nearly all patients have an episode of an acute infection (the area is swollen, tender, and may drain pus). After the infection settles, many patients develop a sinus, which is a cavity below the skin surface that connects to the surface through one or more small openings. Most patients will need a small operation to remove the sinus.

Some patients get repeated infections and inflammation of these sinus tracts, resulting in episodes of swelling, pain, and discharge of pus. Surgery is almost always required to resolve this condition.

The treatment depends on the severity of the disease. An acute abscess is managed with a cut over the skin to release the pus. A chronic sinus usually will need to be excised or surgically opened.

Complex or recurrent disease is treated by more extensive surgery. This may result in a large wound that requires moving different areas of skin to cover the defect. Larger wounds require longer healing times.