Pilonidal cyst

Pilonidal cyst
Two pilonidal cysts that have formed in the gluteal cleft of an adult man.
Classification and external resources
ICD-10	L05
ICD-9	685
DiseasesDB	31128
eMedicine	emerg/771
MeSH	D010864

A pilonidal cyst, also referred to as a pilonidal abscess, pilonidal sinus or sacrococcygeal fistula, is a cyst or abscess near or on the natal cleft of the buttocks that often contains hair and skin debris.^[1]

Signs and symptoms

Pilonidal cysts are often very painful, and typically occur between the ages of 15 and 35.^[2] Although usually found near the coccyx, the condition can also affect the navel, armpit or genital region,^[3] though these locations are much rarer.

Symptoms include:^[4]

• Pain/discomfort or swelling above the anus or near the tailbone that comes and goes
• Opaque yellow (purulent) or bloody discharge from the tailbone area
• Unexpected moisture in the tailbone region
• Discomfort with sitting on the tailbone, doing sit-ups or riding a bike (any activities that roll over the tailbone area)

Some people with a pilonidal cyst will be asymptomatic.^[5]

Pilonidal sinus

A sinus tract, or small channel, may originate from the source of infection and open to the surface of the skin. Material from the cyst may drain through the pilonidal sinus. A pilonidal cyst is usually painful, but with draining, the patient might not feel pain.

Causes

One proposed cause of pilonidal cysts is ingrown hair.^[6] Excessive sitting is thought to predispose people to the condition because they increase pressure on the coccyx region. Trauma is not believed to cause a pilonidal cyst; however, such an event may result in inflammation of an existing cyst. However there are cases where this can occur months after a localized injury to the area. Some researchers have proposed that pilonidal cysts may be the result of a congenital pilonidal dimple.^[7] Excessive sweating can also contribute to the cause of a pilonidal cyst. Moisture can fill a stretched hair follicle, which helps create a low-oxygen environment that promotes the growth of anaerobic bacteria, often found in pilonidal cysts. The presence of bacteria and low oxygen levels hamper wound healing and exacerbate a forming pilonidal cyst.^[8]

The condition was widespread in the United States Army during World War II. The condition was termed "jeep seat" or "Jeep riders' disease", because a large portion of people who were being hospitalized for it rode in Jeeps, and prolonged rides in the bumpy vehicles were believed to have caused the condition due to irritation and pressure on the coccyx.

Treatment

Pilonidal cyst two days after surgery.

Treatment may include antibiotic therapy, hot compresses and application of depilatory creams.

In more severe cases, the cyst may need to be lanced or surgically excised (along with pilonidal sinus tracts). Post-surgical wound packing may be necessary, and packing typically must be replaced once daily for 4 to 8 weeks. In some cases, two years may be required for complete granulation to occur. Sometimes the cyst is resolved via surgical marsupialization.^[9]

Surgeons can also excise the sinus and repair with a reconstructive flap technique, such as a "cleft lift" procedure or Z-plasty, usually done under general anesthetic. This approach is especially useful for complicated or recurring pilonidal disease, leaves little scar tissue and flattens the region between the buttocks, reducing the risk of recurrence.^[8]

Pilonidal cysts recur and do so more frequently if the surgical wound is sutured in the midline, as opposed to away from the midline, which obliterates the natal cleft and removes the focus of shearing stress. An incision lateral to the intergluteal cleft is therefore preferred, especially given the poor healing of midline incisions in this region. A minimally invasive surgical technique, based on J. Bascom's research, was developed in Israel by Moshe Gips et al., back in 2008 [Gips M, et al. "Minimal surgery for pilonidal disease using trephines: description of a new technique and long-term outcomes in 1,358 patients". Dis Colon Rectum 2008; 51: 1656-62]. This procedure consists in the employment of trephines or of biopsy punches which only "core out" and remove the diseased tissue and cyst ("fistulectomy"), without any lateral incision. Therefore, only small surgical "holes" (2 to 4) will residue, measuring, usually, 6 to 8 mm (1/4 of an inch), thus healing very quickly. Work or school activities will be resumed in one or two days, without or with minimal postoperative pain. The excellent outcome of the Gips'procedure (slightly modified) has been confirmed by a research recently conducted by Luigi Basso et al. in Italy on 110 patients [Basso L, et al. "Outcome of 110 cases of Pilonidal Disease treated by modified Gips' procedure. A plea for minimally invasive surgery". 2015: in progress]. One other minimally invasive technique involving the use of a fistuloscope was introduced in 2014 (Endoscopic Pilonidal Sinus Treatment or EPSiT), but this seems pointlessly elaborated and expensive compared to the Gips' technique [Meinero P, et al. "Endoscopic pilonidal sinus treatment (E.P.Si.T.)". Tech Coloproctol 2014; 18: 389-92]. An additional, minimally invasive technique is to treat pilonidal sinus with fibrin glue. This technique is less painful than traditional excisional techniques and flaps, can be performed under local or general anaesthesia, does not require dressings or packing and allows return to normal activities within 1 to 2 days. Long term outcome and recurrence rates are, however, uncertain. ^{[10][11][12][13]}

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 complete surgical excision, if possible without any spillage, and consultation with an oncologist.

Etymology

Pilonidal means nest of hair and is derived from the Latin words for hair (pilus) and nest (nidus).^[2] The condition was first described by Herbert Mayo in 1833.^[14][15] R.M. Hodges was the first to use the phrase pilonidal cyst to describe the condition in 1880.^[16][17]

Notes

References

NHS Choices for pilonidal sinus treatment

• Kanerva, Lasse (2000). Handbook of Occupational Dermatology. Springer. ISBN 9783540640462. 

Pictures of pilonidal sinus and glue treatment http://www.learncolorectalsurgery.com/#/pilonidal-sinus/4549818668

Pictures of Rhomboid Flap http://www.learncolorectalsurgery.com/#/pilonidal-sinus-rhomboid/4549818699