What is a pilonidal cyst?

A pilonidal cyst, also known as a pilonidal sinus, is an acute or chronic inflammation of the subcutaneous fatty tissue.The word sinus pilonidalis is composed of the Latin words "pilus" for hair and "nidus" for nest, thus translated hair nests.

In most cases, the coccyx region is affected, but there are also descriptions of this disease, for example, in the spaces between the fingers or in the navel area. 

The word coccygeal fistula, which is often used in the German language, is actually inaccurate, since this is purely a skin disease and the bone (coccyx) is not involved. 

Asymptomatic form

The asymptomatic form is an incidental finding and does not cause any symptoms. Therapy is not necessary. However, an acute or chronic form may develop.

Acute form

The acute inflamed form presents with pain, swelling and pus. Antibiotic administration is not indicated, but immediate surgical therapy with lateral incision (incision) and drainage of pus is. After 4-6 weeks, a planned minimally invasive surgery should be performed.

Chronic form

In this case, there are rather mild complaints such as a feeling of pressure and fluid secretions. A planned operation is always advisable, since there is no spontaneous healing. The surgical procedure depends on the severity of the findings.

In the disease there are typical symptoms and skin changes. It is a visual diagnosis in the hands of the specialist. An ultrasound may supplement an examination in rare cases; further imaging is not necessary except in cases of recurrence.

• Midline openings (pits): These are found in the midline of the gluteal fold at intervals of a few millimeters. In some cases, hair or hair cell material can be pulled out. Pus comes out in case of infection.
• Pain or feeling of pressure: Scar material forms due to the chronic inflammation or pus in acute courses. Both cause swelling, which leads to pressure or pain on hard surfaces.
• Fluid (secretion): Discharge of pus in abscesses and orange secretion or blood in chronic irritations.
• Displacement of the buttress fold: In larger findings, swelling may cause the buttocks to shift

In Germany, 48 out of 100,000 inhabitants (2012) suffer from pilonidal cyst with an increasing trend. The risk factors for the disease are partly discussed very controversially. Of greater importance in the development of the disease are, for example:

• Increased hairiness in the buttock region with strong, longer hair. Most of our patients showed this finding. However, there are also women with the disease who have a very weak hairiness and often have a light skin type.
• Young men between the ages of 20 and 40. This group is affected more than twice as often as women.
• Heredity: Children of a parent with a sinus pilonidalis have an increased risk of developing the disease.
• Sedentary lifestyle: there are several speculations on this, which could also help explain the increase in the disease, as most people have a sedentary lifestyle.
• Hormonal in women with an increased serum prolactin level.
• Poor hygiene: Is not currently a risk factor, but in our own experience favors the development and recurrence of the disease after surgery.
• Smoking: Also not a proven risk factor, but we know that nicotine decreases microcirculation and leads to poorer wound healing, so better to leave it out.

The sinus usually contains cell debris (detritus), hair and scarred tissue (fistula cavity). These are signs of a chronic reaction of the body to the hair in the subcutaneous fatty tissue, which it regards as a foreign body and tries to remove or seal off by an inflammatory reaction (foreign body granuloma). Since there is no spontaneous healing, this endeavor of the body succeeds only to a limited extent.

The therapy is always a surgical. Antibiotics should therefore not be prescribed, or are only useful for short-term relief. However, pus formation need not always be present. The resulting duct (fistula, porus) usually remains open and "sucks" new hairs into it, so that the disease progresses further and further. 

Proven prevention (prophylaxis) consists only in regular anal hygiene and refraining from smoking. There is no scientific evidence for the effectiveness of hair removal in the affected buttocks section by means of laser (epilation), therefore the costs for laser treatment are not covered by the statutory health insurances even in case of recurrences.

Hair removal by shaving should be avoided except in the early wound healing phase, as the disease is more likely to recur (recurrences).

It does not always have to be a sinus pilonidalis, even though this is the most common condition in the gluteal fold. 

Differentially, acne inversa (hidradenitis suppurativa) should also be considered. This is a skin disease of the sebaceous glands and hair root glands, which leads to small but painful inflammations and in a chronic course has a tendency to form extensive small ducts (fistulas).

In case of findings near the sphincter, anal fistula must always be excluded. These have their origin in the anal canal (rectum) and a completely different surgical strategy is required.

Frequently, however, only the uppermost layer of skin (epidermis) is affected. These are often small tears (rhagades) or the development of psoriasis, neither of which can be treated surgically.