What Is a Pilonidal Cyst?

Sitting down shouldn't hurt — so when the top of the cleft between the buttocks, just above the tailbone, starts to feel sore, swollen, or tender to sit on, it's understandable to wonder what's going on. One common answer in that exact spot is a pilonidal cyst. If you've been told you have one, or you're facing a procedure for one, this guide walks through what to expect, from the first examination to healing afterwards. The video at the top of this page, "Pilonidal Cyst Removal", runs 1 minute 36 seconds and shows a removal procedure; its own description frames the case as pilonidal disease with lateral extension, treated with follicle removal using Bascon's technique.

What you'll notice first

A pilonidal cyst starts as a small pit or opening in the skin near the tailbone. Hair and debris can work their way into that pit, and over time a pocket — a sinus or cyst — can form under the skin. When nothing is infected, you might notice very little: a tiny dimple, occasional tenderness, or slight drainage that comes and goes. When the pocket becomes infected, the picture changes. Expect more obvious swelling, warmth, and pain that makes sitting uncomfortable, sometimes with pus draining from the opening. That kind of spreading skin infection is different from the cyst itself — our guide to cellulitis explains how skin infection is recognised — and a painful, swollen episode is usually what brings people in promptly.

What the examination is like

You can expect the clinician to start by looking at the area and asking how long the soreness, swelling, or drainage has been there, and whether it has flared before. That history matters, because a first, quiet cyst and a repeatedly infected sinus are handled differently. The look itself is brief and focused on the pits, any tracks under the skin, and how far the tenderness extends. Most of the time, the location and appearance tell the story; extensive testing isn't usually the first step for a straightforward case in this classic spot.

What treatment can involve

What happens next depends on whether the cyst is quiet or infected, and how extensive it is. A painful, infected pocket may first need drainage so the trapped material can come out and the pressure settles. For disease that keeps returning or extends under the skin, removal of the cyst and its tracks is the more definitive step — and that's what the anchor video shows. Its description specifically names follicle removal with Bascon's technique for a case with lateral extension, meaning the disease had spread sideways from the midline pits. A much shorter second recording on this page, "Pilonidal Cyst Removal by Laying Open Technique" (25 seconds), shows the alternative laying-open approach, where the tract is opened rather than closed over. Which approach fits you is a judgement your surgeon makes from the extent of your disease — the videos show the range, not a prescription.

What healing tends to be like

Healing is the part people are least prepared for, so it's worth expecting it to take patience. Depending on the technique, a wound in this area may be closed with stitches or left to heal gradually from the inside out, which can mean regular dressing changes over a period of weeks. Sitting can stay uncomfortable for a while, and keeping the area clean and free of loose hair is a routine part of aftercare that your team will explain. A pilonidal cyst is not the same as a surface skin cyst elsewhere on the body — compare our guide to a sebaceous cyst, which sits in the skin itself — which is why follow-up here focuses on the tract healing fully, not just the surface closing. If pain, swelling, or drainage returns during healing, expect to be seen again rather than waiting it out.

Frequently Asked Questions

Where exactly does a pilonidal cyst form?

In the skin at the top of the cleft between the buttocks, just above the tailbone. It usually starts as one or more small pits in the midline, with a pocket or track forming under the skin from there.

Why does hair matter in a pilonidal cyst?

Loose hair can work its way into the small pits in that cleft, and hair and debris trapped under the skin help the pocket form and keep it irritated. That's also why keeping the area free of loose hair is often part of aftercare.

Does every pilonidal cyst need surgery?

Not every quiet cyst is operated on straight away, and an infected episode may first be drained. Removal is more often discussed when the cyst keeps flaring, drains repeatedly, or extends under the skin. Your clinician decides based on your pattern and examination, not on the diagnosis alone.

Can a pilonidal cyst come back after removal?

It can, which is why the extent of the disease and the choice of technique matter, and why completing dressings and follow-up during healing matters too. New pain, swelling, or drainage in the same spot after healing is worth having checked promptly.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Educational only — this article is general information about pilonidal cysts, not medical advice and not a diagnosis. Pain, swelling, fever, or drainage near the tailbone should be assessed by a clinician, who can examine the area directly.