10 Pilonidal Disease

10.1055/b-0038-166144

10 Pilonidal Disease

David E. Beck

Abstract

The proximity of pilonidal disease to the anus has prompted the referral of many patients with this problem to colon and rectal surgeons. Pilonidal sinus is a chronic subcutaneous abscess in the natal cleft, which spontaneously drains through the openings. It is not a “cyst,” as frequently referred to. This chapter discusses the pathophysiology, clinical presentation, diagnosis, and treatment of pilonidal disease.

10.1 Introduction

Although not technically a gastrointestinal tract problem, the proximity of pilonidal disease to the anus has prompted the referral of many patients with this problem to colon and rectal surgeons. The first report of pilonidal disease is attributed to Anderson in 1847 ¹ and the first series of patients to Warren. ² In 1880, Hodges ³ coined the term “pilonidal sinus” from the Latin pilus, meaning hair, and nidus, meaning nest, to describe the chronic sinus containing hair and found between the buttocks. The intent of this term was to note the association of trapped hair in this unusual form of natal cleft skin infection. Pilonidal sinus is a chronic subcutaneous abscess in the natal cleft, which spontaneously drains through the openings. It is not a “cyst,” as frequently referred to in many textbooks and articles. ⁴

10.2 Pathophysiology

The origin of the pilonidal sinus is controversial with two main theories. The congenital theory was initially popular and suggested that a remnant of the medullary canal with infolding of the surface epithelium or a faulty coalescence of the cutaneous covering in early embryonic life led to pilonidal sinus development. ⁵ ^, ⁶ The acquired theory is now widely accepted, but its mechanisms are speculative and varied. Bascom ⁷ believes the affected hair follicles become distended with keratin and subsequently infected, leading to folliculitis and the formation of an abscess that extends down into the subcutaneous fat (▶ Fig. 10.1). Examination of a section of a pit reveals a distended hair follicle with inflammation (▶ Fig. 10.2). Once the abscess cavity is formed, hairs can enter through the tiny pit and lodge in the abscess cavity from the suction created by movement of the gluteal area (▶ Fig. 10.3). Karydakis, ⁸ on the other hand, believes the shaft of loose hair, because of its scales with chisel-like root ends, inserts into the depth of the natal cleft in the midline of sacrococcygeal area (▶ Fig. 10.4). Once one hair inserts successfully, other hairs can insert more easily. Foreign body tissue reaction and infection follow, and the primary sinus of pilonidal disease forms. Secondary openings often occur because of the self-propelling ability of hair to burrow through the skin or spontaneous rupture of the abscess. The author leans toward Karydakis’s explanation.

**Fig. 10.1** Pathogenesis of pilonidal abscess and sinus. ⁷ (With permission © 1980 Elsevier.)

**Fig. 10.2** Photomicrograph of the pit from midline showing chronic inflammation from infected hair follicle. (Courtesy of Andrew R. McLeish, MD.)

**Fig. 10.3** Ingestion of hair by a chronic pilonidal abscess cavity. Scales of hair direct the inward movement of hair. Motion causes movement in the cavity. **(a)** Standing, **(b)** sitting. ⁷ (With permission © 1980 Elsevier.)

**Fig. 10.4** Pathogenesis. Insertion of a shaft of loose hair.

Isolated reports of pilonidal sinus occurring in unusual locations, such as the umbilicus, a healed amputation stump, and interdigital clefts, and the recurrence of the disease in an adequately excised area support the acquired theory of this disease and Karydakis’s concept of hair insertion.

Pilonidal disease and its treatment were significant issues during World War II. ⁹ Seventy-nine thousand U.S. servicemen were hospitalized, each for an average of 55 days. The frequent reactivation of the quiescent sacrococcygeal sinuses among military personnel who entered training for combat duty, with rugged lifestyle and stresses of driving trucks, tanks, and jeeps, led Buie ¹⁰ to call it “jeep disease.”

The main feature of a pilonidal sinus is the subcutaneous fibrous tract that may be lined with squamous epithelium. This subcutaneous tract extends for a variable distance, usually 2 to 5 cm. A small abscess cavity and branching tracts may come off the primary tract (▶ Fig. 10.5). Often, hairs that are usually disconnected from the surrounding skin are seen entering the midline pit (▶ Fig. 10.6). As a rule, hair follicles are not identified. The secondary openings have a different appearance from the primary midline ones in that they are marked by elevations of granulation tissue and discharge of seropurulent material. Hairs, if seen, sticking out of the secondary opening are in the abscess cavity that the body tries to spit out (▶ Fig. 10.6). Most sinus tracts (93%) run cephalad; the rest (7%) run caudad and may be confused with a fistula-in-ano or with hidradenitis suppurativa. ¹¹

**Fig. 10.5** Section of an en bloc specimen shows hairs in a chronic abscess cavity and a sinus tract leading to a secondary opening. (Courtesy of Clyde Culp, MD.)

**Fig. 10.6** Numerous noninflamed midline pits, the primary source of the disease (*small arrow*). Hairs extrude from the secondary sinus (*large arrow*).

Pilonidal sinus is a chronic disease with a natural regression. ¹² The disease usually manifests in puberty and seldom occurs after the third or fourth decade of life. However, pilonidal sinus may occur at any age. ⁸ ^, ¹³ ^, ¹⁴

10.2.1 Predisposing Factors

Tiny skin dimples in the sacrococcygeal area are common in the normal population (9%), but most never become a problem. ¹⁵ Because of the common problems of infected pilonidal sinuses among Army and Navy officers, it was speculated that trauma to the sacrococcygeal area was the primary predisposing factor. However, the acquired theory of folliculitis ⁷ and the spontaneous insertion of hair in the natal cleft ⁸ refute this theory as the primary cause.

Akinci et al ¹⁶ examined 1,000 Turkish soldiers including information on their characters and habits. Eighty-eight (8.8%) of the soldiers had pilonidal sinuses; 48 were symptomatic and 40 were asymptomatic. The factors associated with the presence of a pilonidal sinus were: obesity (weight over 90 kg) (p < 0.0001); being the driver of a vehicle (p < 0.0001); incidence of folliculitis or furuncle at another site on the body (p < 0.0001); and family history of pilonidal sinus (p < 0.0001). The history of pilonidal sinus in the family does not mean a congenital tendency but rather indicates the similar body habitat and hair characteristics.

10.3 Clinical Presentations and Diagnosis

The average patients with pilonidal disease are hirsute and moderately obese in their second decade. ¹⁷ While hirsute people or people with dark hairs may have an increased tendency to develop pilonidal disease, the disease is also seen in people without these features. ¹⁸ People of both sexes and any age can be affected. Pilonidal disease initially may be seen as an acute abscess in the sacrococcygeal area. It frequently ruptures spontaneously, leaving unhealed sinuses with chronic drainage. Once the sinus develops, pain is usually minimal. About 71 to 85% of patients with pilonidal infection are men. ⁵ ^, ¹⁴

The diagnosis is usually suggested by the patient’s history with three common presentations. Nearly all patients have an episode of acute abscess formation, characterized as a painful and indurated swelling or cellulitis in the gluteal cleft. When this abscess resolves, either spontaneously or with medical assistance, many patients develop a pilonidal sinus. This chronic state is confirmed by the sinus opening or dermal pit in the intergluteal fold approximately 5 cm above the anus (▶ Fig. 10.7). Although many sinus tracts resolve, some patients go on to have chronic or recurrent disease after treatment. Treatment methods vary for each stage in pilonidal disease, and will be discussed in detail.

**Fig. 10.7** A midline pit. Note hairs entering the pit.

The differential diagnoses include any furuncle in the skin, an anal fistula, specific granulomas (e.g., syphilitic or tuberculous), and osteomyelitis with multiple draining sinuses in the skin. Actinomycosis in the sacral region has been described as virtually indistinguishable from pilonidal disease.

10.4 Treatment

10.4.1 Pilonidal Abscess

Although the infected epithelial sinus is in the midline, the abscess is usually lateral on either side and cephalad. As a midline wound in the intergluteal cleft heals poorly and slowly, every attempt is made to keep the wound small and off the midline. Drainage of a pilonidal abscess can almost always be performed under local anesthesia in the clinic or emergency room. A longitudinal incision is made lateral to the midline in the coccygeal area (▶ Fig. 10.8). The incision is deepened into the subcutaneous tissue, entering the abscess cavity. Hair, if present in the abscess cavity, must be removed. All the infected granulation tissues and necrotic debris are thoroughly curetted. The skin edges are trimmed to make the abscess cavity an open wound. The wound is lightly packed with fine mesh gauge. Antibiotics are unnecessary. The patient is instructed to irrigate the wound with diluted hydrogen peroxide (dilution 1:4) twice a day for a few days, if possible. This will effectively remove the residual debris. At the very least, the wound should be washed with soap and water in the shower twice a day. The most important aspect is to prevent hairs from getting into the wound and to remove them from the wound. The hairs around the wound should be shaved or plucked for at least a couple of months. A Cytette brush (Birchwood Laboratories, Inc., Eden Prairie, MN), which is commonly used for obtaining Papanicolaou (Pap) smears, is an excellent tool for swabbing the hairs and debris from the wound (▶ Fig. 10.9). During office visits, excess granulation tissue is removed. With diligent wound care, complete healing is common.

**Fig. 10.8** A pilonidal abscess. The incision is made off the midline. ¹⁸

**Fig. 10.9** Cytette brush, an excellent tool to clean the wound.

10.4.2 Pilonidal Sinus

Treatment of pilonidal sinus can be done in one of several ways: nonoperative treatment, incision and curettage, lateral incision (▶ Fig. 10.10) and excision of midline pits, wide local excision with or without primary closure, excision and Z-plasty, or advancing flap operations (Karydakis procedure).

**Fig. 10.10** Lateral incision to the sinus tract. Granulated tissues are scraped with a curette. ⁷ (With permission © 1980 Elsevier.)

Nonoperative Treatment

Klass ¹⁵ believed that the immediate cause of the infection in a pilonidal sinus is a collection of loose hairs and fecal residue in the internatal cleft and that, when an abscess has developed, incision and drainage are all that is required. He thus treated his patients with strict hygiene by washing with soap and water in the perineal and sacrococcygeal area (▶ Fig. 10.11). An abscess is drained, the sinus is kept open, and the area is cleaned. In a series of 15 patients with chronic discharge from the sinuses, 11 were cured, with follow-up of 3 years or longer. In another group of 12 patients who required incision and drainage of the abscess, 10 patients healed, and 2 patients required a second incision and drainage. The follow-up was at least 3 years.

**Fig. 10.11** **(a)** Several openings in midline sacrococcygeal area. **(b)** An incision is made about 1 cm lateral to the midline, and then dissected to connect with the chronic abscess cavity. A lacrimal probe is used to identify the sinus tracts from the midline pits. **(c)** Note the shaggy edges of the wound resulting from laying open of the sinus tracts. **(d)** Complete wound healing at 3 weeks.

The most important conservative treatment comes from Tripler Army Medical Center, Hawaii. Armstrong and Barcia ¹⁹ treated pilonidal disease mainly by shaving all hairs within the natal cleft, 5 cm from the anus to the presacrum. Visible hairs within the sinus are removed, but no attempt is made to probe for hairs within the sinus. If there is an abscess, a lateral incision for drainage is made. This conservative method was applied to 101 consecutive patients during a 1-year period. The wounds healed in all patients. Unfortunately, the length of follow-up and the recurrence rate were not stated in the study.

Injecting phenol into the sinus tract has been advocated by some authors. Schneider et al ²⁰ studied 45 patients with pilonidal sinuses treated with 1 to 2 mL of 80% phenol injected into the sinus. The injection was performed under local anesthesia. Only 60% of the patients completely healed, and it took 6 weeks on average. Besides, 11% develop abscess requiring excision and drainage, and other patients frequently develop local inflammation caused by the phenol. This method of treatment should not be used.

Conversely, Dogru et al ²¹ used crystallized phenol with success. First, they cleaned out and removed hairs from the abscess cavity and sinus tracts. The surrounding skin was protected before applying the crystals into the wound. The crystallized phenol turned into liquid form quickly at body temperature and filled the sinus. It was left in situ for 2 minutes and then expressed out. The procedure may be repeated thereafter as indicated. Of 41 patients so treated, 2 patients had recurrences at 5 and 8 months. The median follow-up was 24 months. The mean recovery time was 43 days. This noninvasive technique may sound good but crystallized phenol is not readily available in most hospitals.

Incision and Curettage

Laying open (unroofing, not excision) and curettage is a minimally invasive procedure to treat pilonidal disease. A meta-analysis in 2015 of 13 studies and 1,445 patients demonstrated that laying open (unroofing) and curettage had high success rates (4.47% recurrence), 1.44% rate of complications, a healing time of 21 to 72 days, and return to work of 8.4 days. ²²

A variation of this was advocated by Buie ¹⁰ and later by Culp. ²⁵ The technique consists of opening the sinus tract in the midline. The debris and granulation tissues are scraped with a curette. The fibrous tissue in the tract is saved and is sutured to the edges of the wound. This technique not only minimizes the size and depth of the wound but also prevents the wound from premature closure. In addition, it is easy to pack and clean the wound (▶ Fig. 10.12). In doing so, the size of the wound is reduced 50 to 60%. ²³ The average healing time is 4 to 6 weeks, with prolonged healing (12–20 weeks) in 2 to 4% and recurrence in 8%. ⁸ ^, ²⁴ Although this technique is simple, it is still more extensive than the lateral incision and lay open of the sinus tracts.