Pilonidal cyst

A pilonidal cyst (from Latin meaning 'hair nest') is a blanket term for any type of skin infection near the tailbone.

Terminology
It is a combination of two Latin words, pilus, meaning hair and nidal, meaning nest. The condition is now referred to as pilonidal sinus disease.

The term "pilonidal cyst" can be misleading, as a majority of the time, this is actually an abscess.

Etymology
It was discussed by Herbert Mayo in 1830. R.M. Hodges was the first to use the phrase "pilonidal cyst" to describe the condition in 1880.

Presentation
These are normally painful, occur somewhat more often in men than in women (though this is debatable), and normally happen in early adulthood (to the 30's). Although usually found near the tailbone, this painful condition can be found rarely in several other places, including the navel and armpit.

Differential diagnosis
A pilonidal cyst can resemble a dermoid cyst, a kind of teratoma (germ cell tumor). In particular, a pilonidal cyst in the gluteal cleft can resemble a sacrococcygeal teratoma. Correct diagnosis is important because all teratomas require surgical complete excision, if possible without any spillage, and consultation with an oncologist.

Causes
A traumatic event is not believed to cause a pilonidal cyst, such an event that has been known to inflame an existing cyst.

It is usually considered to be an acquired condition, but some consider it to be congenital.

Doctors are not sure what causes a pilonidal cyst. An old theory is that a small and harmless cyst has always been present at birth, and that for some reason, it has become irritated and formed a painful abscess. Another explanation is that it is an ingrown hair that has formed an abscess. It is very rare to find hair follicles inside the cyst&mdash;however,it is very common for drained cysts to contain hair, though this is not thought to be the sole cause of the condition.

The condition was widespread in United States Army during World War II. More than eighty thousand soldiers having the condition required hospitalization. It was termed "Jeep riders' disease," because a large portion of people who were being hospitalized for it rode in jeeps, and it was theorized that prolonged rides in the bumpy vehicles caused the condition.

Treatment
Treatment for a pilonidal cyst usually begins when the patient goes to the doctor because of pain. It is treated as an infection, and a doctor might prescribe antibiotics as well as hot compresses and the application of depilatory creams to the lower back and gluteal cleft. Often the cyst is lanced, and surgery is a method that has met with some success for curing pilonidal cysts. Surgery on a cyst in the natal cleft may involve cutting out the skin and sinus in this area (excision), or marsupialization. If the wound is packed, the patient or someone close to the patient is trained to replace the gauze packings. They must be replaced daily for 4 to 8 weeks (but healing, and therefore bandage changes, can last up to 1 year). The condition can recur, even after surgery. The chance of recurrence is much greater if the wound is sutured in the midline, compared to excellent results if the resultant scar is away from the midline, thus obliterating the natal cleft and therefore removing the focus of shearing stresses. Some people develop a chronic non-healing pilonidal sinus which must be treated with surgical excision. Rarely do the complications of a pilonidal cyst result in death, however, due to the possibilities of infection from the abscess, the results of an overly untreated case may prove fatal.

In recurring or non-healing cases, a Z-plasty may be used to reduce shearing stress on the resulting scar. The end result of the procedure is that the buttocks are effectively merged after the cyst is excised, preventing a relapse.