What Causes Pilonidal Sinus to Inflame?

What Is Pilonidal Sinus Disease?

A pilonidal sinus (PNS) is a small cyst or abscess that occurs in the cleft at the top of the buttocks. It can cause severe pain and often becomes infected. If it becomes infected, it may exude pus and blood and emit a foul smell.

A pilonidal sinus is a condition that mostly affects men and is common in young adults.

• Pilonidal means a ‘nest of hairs’.
• A sinus tract is a narrow tunnel (a small abnormal channel) in the body. A sinus tract typically goes between a focus of infection in deeper tissues to the skin surface. This means that the tract may discharge pus from time to time on to the skin.

A pilonidal sinus is a sinus tract which commonly contains hairs. It occurs under the skin between the buttocks (the natal cleft) a short distance above the back passage (anus). The sinus track goes in a vertical direction between the buttocks. Rarely, a pilonidal sinus occurs in other sites of the body.

Infection

Anaerobic bacteria (particularly Bacteroides and Enterococci) predominate over aerobic bacteria (Staphylococci and Haemolytic Streptococci) in the development of infection of the follicles and abscess formation. Anaerobes are predominantly responsible for reinfection and subsequent wound breakdown following surgery. However a more recent prospective study of 49 infected postoperative wounds isolated aerobic bacteria in 43% of cases. Treatment of pilonidal infection should be with broad spectrum antibiotics.

Causes of Pilonidal Sinus

Most doctors think that ingrowing hairs cause pilonidal sinuses. Pilonidal means “nest of hair”. It is common to find hair follicles inside the sinus.

Another theory is that pilonidal sinuses appear after an injury to the sacrococcygeal region (the region relating to both the sacrum [the lower vertebrae] and coccyx). During World War II, more than 80,000 soldiers developed pilonidal sinuses that required a hospital stay. People thought the sinuses were due to irritation from riding in bumpy vehicles. For a while, in the US the condition was actually called “Jeep disease”.

Symptoms of Pilonidal Sinus

The symptoms experienced by someone with a pilonidal sinus include the following:

• Pain at the bottom of the spine.
• Swelling at the bottom of the spine.
• Redness at the bottom of the spine.
• Draining pus.
• Fever.

How Pilonidal Sinuses Treated?

Conservative Treatment

If your case of pilonidal sinus is diagnosed early on, you are not experiencing severe pain, and there is no sign of inflammation, you doctor will usually prescribe a broad-spectrum antibiotic (an antibiotic effective in treating a wide range of different bacteria). If this treatment resolves the problem, your doctor will recommend a follow-up examination as well as regular hair removal (shaving) of the site and particular attention to hygiene.

Lancing

Before this procedure, your doctor will give you a local anesthetic. He or she will then use a scalpel to open the abscess. Then your doctor will clean away any hair, blood, and pus from inside the abscess.

The wound is then packed with sterile dressing and allowed to heal from the inside out. The wound usually heals within four weeks, and many patients will require no further treatment.

Phenol Injection

For this type of treatment, your doctor will first give you a local anesthetic. He or she will then inject phenol (a chemical compound used as an antiseptic) into the cyst. This procedure may need to be repeated several times. Eventually, this treatment will cause the lesion to harden and close.

The recurrence rate after phenol injection is high. Therefore, it is becoming less common and is gradually being replaced by surgery.

Surgery

If you have a recurring problem with pilonidal sinus or you are suffering from more than one sinus tract, your doctor will recommend a surgical procedure.

You will first be given a local anesthetic. Then the surgeon will slice open the lesions, removing all of the pus and debris. Once this process is complete, the surgeon will stitch the wounds closed.

After surgery, your doctor will explain how to change the dressings and will recommend shaving the site to prevent hairs from growing into the wound.

Who gets Pilonidal Sinus?

This condition affects around 26 in 100,000 people each year in the UK. It is rare in children and in people over the age of 40. It is four times more common in men (as they are hairier than women).

Certain factors increase the risk of developing the condition and include:

• A job involving a lot of sitting (a sedentary occupation)
• Being overweight (obesity)
• A previous persistent irritation or injury to the affected area
• Having a hairy, deep natal cleft
• A family history of the condition

This condition used to be called ‘jeep seat’, as it was common in army jeep drivers. This was probably a result of many hours driving and ‘bouncing’ on a hard seat, which caused irritation, minor injury and pressure around the natal cleft.