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Overview

Pilonidal disease is an acquired benign condition of the skin and subcutaneous tissue of the sacrococcygeal region [1–3]. The term pilonidal is derived from the Latin word pilus meaning hair and nidus meaning nest, describing the disease of the hair follicle in the ‘nest’ formed in the natal cleft [4–6]. The disease was first described in 1833 by British pathologist, anatomist, and surgeon Harold Mayo, who described the finding of a hair follicle containing sinus in the sacrococygeal region in a female patient [4]. Hair in the natal cleft is thought to be the culprit as per the causative theory [7]. Bascom stated in his original paper that pilonidal disease was caused by enlargement of the midline pits in the natal cleft that contained distorted hair follicles. He further described that the enlarged pits had keratin accumulation and the distorted hair pushes inferiorly causing coalescence of adjacent follicles. This results in inflammation in the subcutaneous tissue and progresses to abscess formation [8, 9].

Pilonidal disease is more common in obese individuals, people with thick hair in the natal cleft, patients with sedentary lifestyles and following trauma to the sacrococygeal region [7, 10–12]. Buie referred to it as ‘Jeep disease’ in 1944 and Hardaway called it ‘Jeep rider disease’ in 1958. This was because young male soldiers, who were predominately affected, had the highest risk of disease. It was suggested that the soldiers’ frequent sitting on the uncomfortable jeep seats, in combination with uneven driving condition caused coccygeal trauma resulting in the disease [5]. The etiology of disease is not completely understood, but it is thought that the anatomy of the natal cleft is the culprit. The natal cleft has minimal subcutaneous tissue with the skin being closely adherent to the sacrum and coccyx. The gluteal region adds downward strain to this tightly adherent skin, due to the weight of the musculature. In addition to the anatomy, the natal cleft, like the axilla, is more likely to be an area of moisture and bacterial accumulation. The mechanics of walking allows the skin of the gluteal folds and natal cleft to rub against each other, causing the migration of debris as well as skin trauma. These factors contribute to pilonidal disease formation [5, 12].

The disease often has a chronic course, initially presenting with pilonidal abscess formation, with most patients experiencing disease recurrence [5, 7]. The disease affects males more often than females (3:1 prevalence), affecting males between the ages of 15–30 [2, 3, 5, 11, 12]. The most common presentation is pain, swelling, and/or drainage from the natal cleft [2]. The disease can also be asymptomatic in 3.7% of affected individuals, with one or more blind sinus openings in the natal cleft [3].

Management

The aim of treatment is to cure disease in the simplest way possible, while causing little pain and minimal effect on patients’ lifestyles, while achieving low recurrence rates [1, 4, 6, 13]. Treatment can be divided into conservative and surgical approaches to management of both disease and recurrence (Figs. 6.1, 6.2 and 6.3).

Fig. 6.1
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Midline pits (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Fig. 6.2
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Pilonidal sinus (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Fig. 6.3
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Chronic pilonidal wound (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Conservative Approaches

Controlling hair growth in the sinuses is important in preventing disease progression in early pilonidal disease and preventing recurrences as hair growth in the natal cleft has been linked to pilonidal disease [7]. Hair growth can be controlled by shaving, waxing, electrolysis, and use of depilatory creams [7]. Another technique for hair removal is laser depilation. Khan et al. had good results in preventing disease recurrence using this technique. Photoelectrolysis has the advantage of being able to reach deep areas not easily accessed by other techniques of hair removal [7]. The complications of laser depilation include skin erythema and irritation, hyperpigmentation or hypopigmentation, and skin crusting [7]. The paper emphasized the adherence to hair removal techniques and suggested that lapse in adherence as the cause in disease recurrence.

Phenol injection into pits has been suggested. The mechanism of action is thought to be due to destruction of the epithelium in the pit, leading to inflammation and scar formation [14]. The procedure is performed under local anesthesia on an outpatient basis. Weekly phenol instillation in addition to local hair removal has a success rate of approximately 60% [6] with recurrence rate of approximately 11% [15]. High recurrence rate is a disadvantage of phenol injection, and is thought to be due to inadequate phenol penetration of extensive sinus tracts [3]. The complications of this therapy are local toxicity, resulting in skin irritation, burns, cellulitis, and abscess formation [6]. This is avoided by protecting the surrounding skin and with the application of ointment containing nitrofurantoin prior to phenol application which can reduce the risk of skin burns [6, 16]. Analgesia, topical anesthetics use, and wound care can aid in skin healing if phenol toxicity occurs (Figs. 6.4, 6.5, 6.6, and 6.7).

Fig. 6.4
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Pilonidal sinuses

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Fig. 6.5
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Connection between pilonidal sinus tracts delineated following peroxide injection

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Fig. 6.6
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Unroofing of pilonidal disease (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Fig. 6.7
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Marsulpialzation following unroofing (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Antibiotic use has a limited role in conservative management of pilonidal disease. The use of preoperative antibiotics has not shown benefit in wound healing, preventing complications, or disease recurrence [16]. Equivocal data exists for the use of antibiotics postoperatively [2, 16]. In chronic pilonidal disease, antibiotic use is only recommended in cases of associated cellulitis, immunosuppression, and systemic illness [14].

Surgical Approach

Surgical approaches are offered when there is failure of conservative management and in cases of chronic pilonidal disease [1, 15]. There are several approaches ranging from minimally invasive procedures, such as pit picking and more extensive procedures such as wide local excision.

In the acute stage incision and drainage vs needle aspiration followed by antibiotic course is recommended for acute pilonidal abscesses [14]. Incision and drainage results in complete wound healing in 60% of cases [15]. Definitive surgical excision is recommended after inflammation subsides, to address the resultant wound. Disease recurrence occurs in 10–15% of cases despite complete wound healing, as drainage of a pilonidal abscess does not address the underlying cause of its pathology [15].

Pit picking is one of the minimally invasive procedures. There are various methods of performing this type of surgery. A common feature in all these methods is the excision and removal of midline pits followed by drainage or curetting of the subcutaneous tissues. The aim of these techniques is to remove minimal amount of tissues. It is important to note that the sinus tract is not excised with these techniques. The advantage of this method is that it is performed on an outpatient basis, has short wound healing time and short recovery time. The disadvantage is a recurrence rate of approximately 20–25% in 5 year follow-up [14].

Sinusectomy first described by Soll et al. is another minimally invasive technique. The sinus tracts are probed and injected with methylene blue. The sinus tracts are then excised following the methylene blue delineation. The wounds are left open to close by secondary intent [17]. A recurrence rate of 5% was reported in the study [17]. This technique is recommended for patients with less than three pilonidal pits [14].

Unroofing and marsupialization (UM) of the sinus tracts is another surgical option [1]. In this procedure no healthy, normal tissue is removed and only affected tissue is incised [1]. This technique still results in a 1–2 cm open wound, but the wound is much smaller than the wound caused by wide local excision (WLE) [14]. Rouch et al. described a low recurrence rate with UM when compared to WLE in their retrospective review [1].

The most common procedure offered is wide local excision with or without closure [1, 2, 12, 14, 17]. In this procedure all of the involved tissue is excised and the resultant wound is either closed or left to close by secondary intent [1]. The technical approach of WLE is similar to sinusectomy and UM, in that the sinus tracts are probed and sometimes injected with methylene blue prior to being excised; however, the extent of excision is larger [14]. The disadvantage of allowing the wound to close by secondary intention is prolonged wound healing time, increased recurrence rate, patient effort in wound care and time off work [2, 14].

Midline and off midline closure is used in primary closure following WLE. Shorter time of wound healing is noted with primary closure. Off midline closure is shown to have faster healing rates, lower infection as well as lower recurrence rates compared to midline closure [2]. Three off midline procedures commonly used are the Karydakis flap, the Limberg flap and the cleft lift procedure (Bascom II). The advantage of off midline closure is that it first removes the chronically diseased tissue and second it flattens the natal cleft, thereby minimizing recurrence due to anatomic and mechanical stress [5]. Disadvantage of the off midline closure is tension on the suture line, resulting in wound dehiscence, and esthetic of ultimate scar [18]. The most common complications following off midline flap closure is hematoma, seroma and wound separation [5, 11]. The use of drains intra-operatively may prevent the formation of seromas and hematomas. If wound hematoma or seroma develop, fluid aspiration with large bore needle is suggested. Wound separation is treated with wet to dry dressing applied to the region (Table 6.1).

Table 6.1 Flap closure techniques following WLE and their complications
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Pilonidal disease can recur up to 20 years after surgery, but 60% will recur within 5 years [12]. Early recurrence in midline closures is thought to be secondary to the surgical site infection and occur in up to 24% of case that undergo WLE with primary closure [2, 3]. The administration of systemic antibiotics has been reviewed in several randomized controlled trials, showing no significant benefit [2, 14, 15]. Postoperative antibiotics can be used as an adjunct following surgical excision; however studies have shown mixed results in term of wound healing and recurrence rate [15]. Nyugen et al. suggested the use of gentamycin collagen sponge to reduce the local infection rates; however, the study did not reach statistical significance [2]. Other studies failed to show that the use of gentamycin improved wound healing and prevented disease recurrence [2, 15].

Complications

Regardless of whether conservative or surgical treatment strategies are utilized, pilonidal disease often leads to post-therapeutic complications, including poor wound healing and disease recurrence. Male gender, obesity, hirsutism, smoking, family history, poor hygiene, sinus size, and the surgical procedures are risk factors for complications and recurrence [7, 10–12, 15, 19]. One study, done by Lesalnieks, showed that smokers had increased postoperative wound complications following both minor surgical procedures as well as larger procedures with off midline closures [19]. Pilonidal disease recurrence was also reported to be increased in smokers when compared to nonsmokers [19]. Surgeon experience was also considered in disease recurrence. Pilonidal disease recurred in 44% of patients when the Karydakis flap was performed by an inexperienced surgeon, while the recurrence rate was 9% when performed by an experienced surgeon [19]. A correlation also exists between sinus pit size and number of pits and disease recurrence [20]. Incomplete sinus tract excision results in disease recurrence [20]. Method of anesthesia also affected disease recurrence. Smaller and inadequate surgical excision with local anesthesia use had higher recurrence rates compared to either spinal or general anesthesia [20].

Wide local excision with primary closure minimizes wound healing time and has shorter recovery time prior to patients returning to work [2]. Off midline flap closures are preferred as these procedures have lower recurrence rate compared to midline closures [20]. Onder et al. suggested that primary midline closures had higher recurrence rates while flap closure had higher postoperative complications [20].

Minor postoperative complications, such as seroma, hematoma, local wound infections, and wound dehiscence is reported to between 16 and 17% following WLE and primary closure [21]. Should a seroma or hematoma develop, fluid aspiration is recommended. Intra-operative wound drain placement is used to prevent fluid accumulation. Antibiotics, be it systemic vs local, is used to address the complication of local wound infection. Wound separation is treated with local dressing (Figs. 6.8, 6.9, 6.10 and 6.11).

Fig. 6.8
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Unroofing of extensive pilonidal disease

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Fig. 6.9
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Marsupialization

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Fig. 6.10
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Recurrent pilonidal cyst initially treated with Limberg flap (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Fig. 6.11
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Lichen Sclerosis minimking pilonidal disease (Photograph courtesy of Charles O. Finne MD, Minneapolis)

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Irrespective of surgical technique chosen, hair removal and maintaining strict hygiene have been shown to prevent disease recurrence [16].

Malignant transformation is a rare complication of chronic recurrent pilonidal disease. Carcinoma developing in the pilonidal sinus tract is rare and occurs in less than 0.1% of cases of chronic, untreated, recurrent pilonidal disease [16, 22]. Chronic pilonidal disease is present for approximately 20 years prior to malignant degeneration [22, 23]. Squamous cell carcinoma is the most common carcinoma, occurring in 90% of cases. The remaining 10% is made up of basal cell, mixed squamous and basal cell, and adenocarcinoma [22]. The disease presents as an aggressive, rapidly progressing fungating ulcer [16]. The carcinoma is locally invasive but rarely has distant metastasis. Treatment of choice is en-bloc surgical excision with closure of the resultant defect with skin grafting or flaps [22]. The disease has a poor prognosis and high recurrence rate of 50% despite intervention [16]. Adjuvant chemotherapy and radiotherapy is used to reduce disease recurrence [23].

Misdiagnosis

Differential diagnosis for pilonidal disease includes hidradenitis suppurativa, congenital dermal tract, myelomeningocele, meningocele, dermoid cyst, tailgut cyst, teratoma, or lipoma to mention a few misdiagnoses.

Hidradenitis suppurativa (HS) is a disease that affects skin with high concentration of apocrine glands especially the axilla, inframammary, inguinal, perineal, and perianal regions. The etiology of HS is thought to be secondary to occlusion of hair follicles, with resultant dilation, follicle rupture, and coalescing tract formation [24]. This is similar to the pathogenesis of pilonidal disease. If disease is confined to the perianal and perineal tissue, patients present with pain and malodorous drainage similar to that of pilonidal disease. On physical examination subcutaneous abscesses with multiple draining tracts are seen. Treatment ranges from conservative management to surgical management with wide local excision and wound closure by secondary intent [24].

Congenital sinus tracts may be seen anywhere from the nose to the coccyx, occurring at the midline or adjacent to the midline [25]. The sinus tracts are lined with stratified squamous epithelium, like skin, and contain dermal appendages [25]. The tracts can extend as far as the spinal cord and may be complicated by meningitis or be linked to tracts ending in the subcutaneous tissue.

Tailgut cysts are congenital lesion in the retrorectal space, considered to be embryological remnants of postnatal intestinal tract [26]. As tailgut cysts are found in the retrorectal space they present with signs of mechanical obstruction to the rectal/anal canal or urinary system as the cysts increase in size. Tail gut cysts may be misdiagnosed as pilonidal disease and they can also incidentally found as a sacrococcygeal dimpling in the natal cleft [26]. Tailgut cysts may be surgically excised; however, this is associated with a high morbidity and complication rate [26].

Myelomeningocele, meningocele, and ependymoma are defects of the central nervous system that can occur along the central nervous tract in the sacrococcygeal region [27]. As these lesions present as a fluctuant mass in the sacrococcygeal region they may be misdiagnosed as pilonidal disease. The initial management would be to aspirate or incise and drain the lesion, which will not result purulent fluid. Surgical excision and pathological evaluation confirms diagnosis [27].

Understanding the epidemiology and disease presentation is important in effective diagnosis of pilonidal disease. Sending tissue sample for pathological evaluation will also aid in confirming diagnosis.