Pilonidal Cyst - Causes, Symptoms and Surgery

The pilonidal cyst, also called a pilonidal abscess, is an injury that usually occurs in the upper part of the fold that divides the buttocks just above the anus.

The pilonidal cyst is a very common disease, which does not usually cause major complications, although it is very uncomfortable and difficult to treat in some cases.

Pilonidal cyst
Pilonidal cyst

What is a pilonidal cyst

A cyst is a closed sac, formed by a membrane, and with some content inside. Most of the cysts that appear in our body contain liquid, as is the case of the renal cyst. If there is pus in the cyst, it is called an abscess.

The term pilonidal means "nest of hairs". The pilonidal cyst was named because it is very common to find hair in the cyst.

The pilonidal cysts form preferentially in the upper part of the fold that divides the buttock, 4 to 5 cm above the anus, in the coccyx region, but may also appear in other places, such as around the navel, armpits or scalp.

Pilonidal cyst is a disease that occurs predominantly in young men, between 15 and 25 years of age. Men over 40 rarely develop this disease.


The origin of the pilonidal cyst has not yet been fully elucidated. When the disease was first described, in the early nineteenth century, it was thought that its origin was a malformation, which caused the embryological tissues to remain in the subcutaneous region. However, a large increase in the incidence of the disease in soldiers during World War II led the scientific community to rethink its origins. In the US Army alone, more than 80,000 soldiers had cases of pilonidal cyst during battles.

If it was a congenital disease, how could so many soldiers develop it in so short a time?

Nowadays, the pilonidal cyst is considered a disease that is acquired during the life. The mechanism currently proposed would be the penetration of hair into the skin. These hairs accumulate in the subcutaneous tissue and provoke an inflammatory reaction, which leads to the formation of the cysts. In some cases, the hair enters the skin and forms a small subcutaneous canal before giving birth to the cyst.

The pilonidal cysts usually present hair, but we can not find a hair follicle, which shows that the hair was not born in this place, but rather, was pushed there.

If there is also invasion of bacteria along with the hair, the cyst may become infected, forming pus. As we have already explained, an infected cyst gives rise to an abscess.

Pilonidal cyst occurs more often in young people, who usually have wider hair follicles, facilitating the penetration of the hair into the skin. Other important risk factors are traumas in the region of the coccyx, professional activities or sports that require a lot of sitting time, obesity, excess hair in the region of the coccyx or having a deep buttocks fold. In the case of World War II, the origin of so many pilonidal cysts seems to have been the excessive time spent on Jeeps, which kept the soldiers seated for a long time and still caused minor trauma to the coccyx due to the unstable terrain of the vehicles.


The pilonidal cyst can present itself in different ways. There are cases of small cysts that do not become infected and therefore remain asymptomatic for a long time. There are cysts that ignite and form a reddish, hot, painful nodule beneath the skin. The pilonidal cysts can create one or more channels, and can fistulize to skin (form channels with exit holes in the skin). If the cyst is infected, pus from the abscess may seep through these channels and drain through the skin.

The inflamed cysts may present pain and prevent the patient from sitting down. Fever is uncommon and the patient usually has no complaints other than the inflamed lesion.

Half of the patients have an acute disease, with rapid abscess formation, while the other half presents a more chronic form, with fistulization and persistent drainage of purulent material through the orifice.

There are reports that chronic forms, if neglected, may, after a few years, give rise to squamous cell carcinoma, which is a form of skin cancer). This complication, however, is rare.

Treatment and surgery

Treatment of the pilonidal cyst is surgical. Antibiotics or medicines do not solve the problem definitively.

Initially, a small incision of the skin under local anesthesia is sufficient to drain the contents of the cyst. This procedure is simple and can be done outpatient, outside the hospital environment.

The recovery time can reach 5 weeks. The problem is high rate of recurrence.

If the cyst returns after drainage, more extensive surgery may be necessary for complete removal of the cyst. In these cases, the recovery time is much longer, reaching three months.

The most effective surgical form is also the worse recovery. The surgeon can open the skin, remove the cyst and leave the wound open, without stitches, so that it heals naturally (a technique called 2nd intention healing). This technique has a low recurrence rate, but it needs a lot of care with wound dressing to avoid local infections while it is not fully healed.

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