A lump near the tailbone: what a pilonidal sinus is

A pilonidal sinus is a small tunnel under the skin at the top of the buttock cleft, usually kept open by hair that has worked its way in. It is not a cyst, it is not caused by poor hygiene, and it will not close on its own.

Most people who develop one do not know the word. They search for a lump near the tailbone, a boil at the top of the bum, or a hole above the buttocks that leaks. If any of those describes what you are dealing with, this page is about your problem.

Who gets it

Typically men between 15 and 35, though women get it too. Sitting for long periods, a deep natal cleft, coarse or dense body hair, and friction all raise the risk. In the UAE the long driving commutes and desk-bound days are a genuine factor, and heat and sweat do not help.

How it usually presents

In one of three ways. Some notice only a small pit or dimple in the cleft and nothing else for years. Some notice intermittent discharge, damp underwear, or a smell. And some present with an acute abscess: a hot, swollen, exquisitely painful lump that makes sitting impossible and arrives over about 48 hours.

The abscess is the emergency. It needs draining, and draining brings enormous relief. But drainage treats the abscess, not the sinus underneath, which is why so many people are told the problem is solved and find it back six months later.

Why it keeps coming back

Because the tunnel and its openings are still there. Until the tract itself is dealt with, hair and debris keep entering and the cycle repeats. Recurrence is not a sign that you did something wrong or that the first surgeon was careless. It is what happens when the sinus is not addressed.

The treatment options, honestly compared

Wide excision, left open. The tissue is cut out and the wound packed daily until it fills in from the base. It works and has the longest track record. It also means weeks to months of dressing changes and a genuinely disruptive recovery.

Flap procedures (Karydakis, Limberg, Bascom). The cleft is flattened and the wound closed off the midline. Recovery is shorter than open excision and recurrence rates are good, but it is a larger operation with a scar and a risk of wound breakdown.

Endoscopic and laser treatment (EPSiT with SiLaC). The tract is inspected with a tiny endoscope, cleaned of hair and debris, then closed with a laser fibre through the existing openings. No excision, no flap, no packing.

The honest caveat: laser treatment is not right for every sinus. A very extensive tract, or one that is acutely infected, may need drainage first or a different approach altogether. Anyone who tells you one technique suits every patient is selling, not advising. How EPSiT and SiLaC work, in detail.

Reducing the chance of recurrence

• Keep the area free of hair while it heals. Laser hair reduction over the cleft has reasonable evidence behind it.
• Keep the area dry, especially through summer.
• Break up long periods of sitting where you can.
• Do not wait for a third abscess before dealing with the tract.

When to be seen urgently

Spreading redness, fever, or pain severe enough that you cannot sit or sleep means an abscess that needs draining now, not an appointment next week.

Dr Kerim Erdem Ulucay is a DHA-licensed Specialist General and Laparoscopic Surgeon and a certified laser proctologist, consulting in Jumeirah 1 and JLT. To describe your case before booking, message +971 55 558 4957 or use the contact page.

General information, not a diagnosis. Treatment choice depends on examination.