Pilonidal Cyst

What causes a pilonidal cyst

"Pilonidal" means "nest of hair". The current understanding is that the disease is acquired, not something you are born with. Loose hairs, from the area itself or from the head and back, collect in the deep crease between the buttocks. Friction and movement drive the sharp ends of the hairs into the skin, often through stretched hair follicles. The body treats the hair as a foreign body, forming a tract (sinus) lined with granulation tissue that can become infected.

Risk factors

• male sex, and age between puberty and about 40
• thick, coarse or curly body hair
• a deep buttock crease
• obesity
• long periods sitting, such as driving or desk work (it was common in World War II jeep drivers)
• poor hygiene of the area and heavy sweating
• a family history

Symptoms

Many people have tiny pits in the midline of the buttock crease and no symptoms. When infection develops:

• pain at the top of the crease, worse sitting or getting up
• a tender, warm, red swelling, often slightly to one side
• pus or blood-stained fluid draining, sometimes with a bad smell, and hair visible in the opening
• fever with an abscess
• a recurring cycle of swelling, drainage and settling (chronic pilonidal sinus)

How it is diagnosed

A doctor diagnoses it by looking: the typical site, midline pits and a nearby swelling are enough. They will check that it is not something that looks similar:

Ultrasound or MRI is occasionally used for complex or recurrent disease.

Treatment

Acute abscess

• Incision and drainage: the doctor numbs the skin, makes a small cut, lets out pus and cleans out hair. Pain relief is usually immediate. The wound is packed or left to heal from the inside.
• Antibiotics are added only for spreading cellulitis, a weak immune system or diabetes. They do not cure the cyst alone.
• About half of people who have an abscess drained develop chronic or recurrent disease.

Chronic or recurrent pilonidal disease

• Pit picking and minimally invasive procedures: the small pits are removed and hair cleared out of the tract, sometimes with a laser or endoscope. Recovery is fast, with less time off work.
• Excision left open: the tract is cut out and the wound heals over weeks to months with dressings. Recurrence is low but healing is slow.
• Excision with closure: stitching the wound in the midline heals faster but has more recurrence. Off-midline flap techniques (such as the Karydakis or cleft lift) flatten the crease and have lower recurrence rates.

Hair removal

Shaving, depilatory creams or laser hair removal of the crease after treatment helps prevent recurrence. Laser hair removal has good evidence for reducing it.

Home care while you wait to be seen

• Warm compresses for 10 to 15 minutes several times a day can ease pain and help a small abscess drain.
• Over-the-counter pain relievers, following the label dose.
• Do not squeeze it, which can push infection deeper.

Complications

• recurrence, the most common problem, in up to 1 in 5 people after surgery
• slow wound healing
• cellulitis or spreading infection
• rarely, after many years of untreated chronic disease, a type of skin cancer (squamous cell carcinoma) in the sinus

Prevention

• Keep the crease clean and dry, and wash daily.
• Remove hair from the area regularly or with laser.
• Lose weight if overweight.
• Take breaks from prolonged sitting.

Frequently asked questions

What does a pilonidal cyst look like?

When infected, it is a red, swollen, tender lump at the top of the buttock crease near the tailbone, often with a small opening that drains pus or blood. Between flares it may only show as tiny pits in the midline of the crease, sometimes with hair poking out.

Can a pilonidal cyst go away on its own?

An inflamed cyst may burst and drain, and symptoms can settle. The underlying tract usually remains, so flares often return. A painful abscess should be drained by a doctor, and people with repeated episodes usually need a procedure to remove the tract.

Is a pilonidal cyst the same as a pilonidal sinus?

They describe the same disease. A pilonidal sinus is the tract or channel under the skin. A pilonidal cyst or abscess is when that tract becomes swollen with pus. Both are part of pilonidal disease.

How long does recovery from pilonidal surgery take?

It depends on the technique. Minimally invasive procedures heal in a few weeks. Wounds left open to heal can take 6 to 12 weeks or longer. Flap and closed techniques heal in 2 to 4 weeks, though wound breakdown can delay this.

Why do pilonidal cysts keep coming back?

Recurrence happens when hair keeps entering the deep crease, tracts are left behind, or a midline wound heals poorly. Regular hair removal, keeping the area clean, losing excess weight and surgery that flattens the crease reduce the risk.