Pilonidal sinus

Pilonidal sinus

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Pilonidal sinus

A pilonidal sinus (PNS), also called Pilonidal cyst is a small hole or tunnel in the skin. It may fill with fluid or pus, causing the formation of a cyst or abscess. It occurs in the cleft at the top of the buttocks. A pilonidal cyst usually contains hair, dirt, and debris. It can cause severe pain and can often become infected. If it becomes infected, it may ooze pus and blood and have a foul odor.

Who can get a pilonidal cyst?

Anyone can get a pilonidal cyst, but certain people are at higher risk:

  • Men (men are three to four times more likely to be diagnosed with a pilonidal cyst than women)
  • People between puberty and age 40 (the average age is between 20 and 35).
  • Workers who sit all day (like truck drivers and office workers).
  • Overweight people (ranging from overweight to obese).
  • People with thick or rough body hair (this can run in your family).
  • People who wear tight clothing (this can worsen the skin condition).

Pathophysiology

The most widely accepted theory for pilonidal sinus disease development is starting from a hair follicle in the intergluteal cleft becoming infected or inflamed.

This inflammation obstructs the opening of the follicle, which extends inwards, forming a ‘pit’ (a characteristic feature of pilonidal sinus disease). A foreign body-type reaction may then lead to formation of a cavity, connected to the surface of the skin by an epithelialised sinus tract.

What are the causes of pilonidal sinus disease?

The exact cause of this condition isn’t known, but its cause is believed to be a combination of changing hormones (because it occurs after puberty), hair growth, and friction from clothes or from spending a long time sitting.

Activities that cause friction, like sitting, can force the hair growing in the area to burrow back under the skin. The body considers this hair foreign and launches an immune response against it, similar to how it would react when dealing with a splinter. This immune response forms the cyst around your hair. Sometimes a person may have multiple sinuses that connect under the skin.

Clinical Features

Pilonidal sinus disease most comm only presents as a discharging and intermittently painful sinus in the sacrococcygeal region.

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A pilonidal abscess can form when a pilonidal sinus becomes infected. This will present as a swollen and erythematous region. On examination, there will be a fluctuant and tender mass, as well as systemic features of infection.

The main distinguishing feature compared to a perianal fistula is that a pilonidal sinus does not communicate with the anal canal; if there is any uncertainty on initial inspection, a rigid sigmoidoscopy or MRI imaging can be performed to assess for any internal opening of a tract.

Management and treatment

Conservative treatment

If your case is diagnosed early on, you aren’t experiencing severe pain, and there’s no sign of inflammation, it’s likely that your doctor will prescribe a broad-spectrum antibiotic. A broad-spectrum antibiotic is an antibiotic that treats a wide range of bacteria. It’s important to realize that this won’t heal the sinus tract, but it will give you relief from the infection and discomfort. Your doctor will recommend that you get a follow-up exam, regularly remove hair or shave the site, and pay particular attention to hygiene.

Lancing

This procedure alleviates symptoms from an abscess, or a collection of pus inside the sinus. Before this procedure, your doctor will give you a local anesthetic. They will then use a scalpel to open the abscess. They will clean away any hair, blood, and pus from inside the abscess.

Your doctor will pack the wound with sterile dressing and allow it to heal from the inside out. The wound usually heals within four weeks, and many people don’t require any further treatment.

Phenol injection

For this type of treatment, your doctor will first give you a local anesthetic. They 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.

This treatment has a very high recurrence rate. Therefore, it’s uncommon in the United States. Doctors turn to surgery as the treatment of choice in some cases.

Surgery

If you have a recurring PNS or if you have more than one sinus tract, your doctor will recommend a surgical procedure.

You will first be given a local anesthetic. Then, the surgeon will 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 hair from growing into the wound.

What complications are associated with pilonidal sinus disease?

There are a number of complications that may arise from PNS. These include wound infection and a recurrence of the PNS even after surgery.

Signs that the wound is infected include:

  • severe pain
  • inflamed, swollen skin
  • a temperature of 100.4°F or higher
  • blood and pus seeping from the wound site
  • a foul odor coming from the wound
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