eMedicine Specialties > General Surgery > Colorectal

Pilonidal Disease

Author: James de Caestecker, DO, Instructor, Department of Surgery, MCP Hahnemann University
Coauthor(s): Barry D Mann, MD, Program Director, Associate Professor, Department of Surgery, Division of General Surgery, MCP Hahnemann University; Andres E Castellanos, MD, Assistant Professor, Associate Surgical Residency Program Director, Department of Surgery, Drexel University College of Medicine; Jason Straus, MD, Staff Physician, Department of Surgery, Wright State University School of Medicine
Contributor Information and Disclosures

Updated: Aug 24, 2009

Introduction

Pilonidal disease was first reported in 1833. Sacrococcygeal pilonidal sinus is a common disorder among young adults. Observed most commonly in people aged 15-30 years, it occurs after puberty, when sex hormones are known to affect the pilosebaceous gland and change healthy body hair growth. The onset of pilonidal disease is rare in people older than 40 years.¹

History of the Procedure

In the 1950s, pilonidal sinus disease was thought to be of congenital origin rather than an acquired disorder. The pilonidal sinus and abscess were thought to be secondary to a congenital remnant of an epithelial-lined tract from postcoccygeal epidermal cell rests or vestigial scent cells. Sinuses to the neural canal can occasionally extend to the dura, but these are rare and are located in the lumbar region rather than in the sacral region. Pilonidal disease is now widely considered to be an acquired disorder, based on the observations that congenital tracts do not contain hair and are lined with cuboidal epithelium. The recurrence of the disorder after complete excision of the disease tissue down to the sacrococcygeal fascia and the high incidence of chronic pilonidal sinus disease in patients who are hirsute further support an acquired theory of pathogenesis.

Problem

In a census and survey of patients admitted to British hospitals in 1985 for treatment of pilonidal sinus disease, it was found that 7000 patients required hospitalization for an average of 5 days. The hospitalization of these patients for the treatment of pilonidal disease resulted in a loss of productivity and earnings, as well as a disruption of education, because patients recovered in the hospital.

Treatment options are now available that provide a rapid rate of cure and a lower recurrence rate, and that minimize the number of hospital admissions. Although numerous randomized clinical studies have evaluated different treatments, no clear consensus has been reached as to the optimal medical or surgical treatment of pilonidal disease.

Frequency

The incidence rate of pilonidal disease is approximately 0.7%. Males are affected 2.2-4 times more frequently than females. During a population study involving college students, the incidence rate was found to be 1.1% (365 of 31,497 people) in males and 0.11% (24 of 21,367 people) in females. The onset of the disease is earlier in females, which may be due to the fact that puberty occurs earlier in females.

Etiology

The incidence of pilonidal disease is also affected by hair characteristics, such as kinking, medullation, coarseness, and growth rate. White persons are affected more frequently than are African or Asian persons. Other factors affecting the disease's incidence are increased sweating activity associated with sitting² and buttock friction, poor personal hygiene, obesity, and local trauma, which help to explain why pilonidal sinus disease is common in army recruits. In an article examining the condition in Turkish soldiers, the incidence was found to be 8.8%, with the correlation factors known to be family history, obesity, being the driver of a vehicle, and the presence of folliculitis or a furuncle at another site on the body.³

Pathophysiology

After the onset of puberty, sex hormones affect the pilosebaceous glands, and subsequently, the hair follicle becomes distended with keratin. As a result, a folliculitis develops, which produces edema and follicle occlusion. The infected follicle extends and ruptures into the subcutaneous tissue, forming a pilonidal abscess. This results in a sinus tract that leads to a deep, subcutaneous cavity. In 90% of cases, the direction of the sinus tract is cephalad, which coincides with the directional growth of the hair follicle. This usually places the tracking follicle approximately 5-8 cm from the anus. In the rarer instance that the sinus is located caudally, it is usually found 4-5 cm from the anus. The laterally communicating sinus overlying the sacrum is created as the pilonidal abscess spontaneously drains to the skin surface. The original sinus tract from the natal (intergluteal) cleft becomes an epithelialized tube. The laterally draining tract becomes a granulating sinus tract opening.

Loose hairs are drilled, propelled, and sucked into the pilonidal sinus by friction and the movement of the buttocks whenever a patient stands or sits. Hair enters tip first, and the barbs on the hair prevent it from being expelled, causing the hair to become entrapped. Physical examination occasionally may reveal a tuft of hair emerging from the midline opening in the natal cleft. This trapped hair stimulates a foreign body reaction and infection. Rarely, foreign bodies other than human hair can cause this disease process. Rare case reports exist in which the hair did not come from the patient but instead came from a bird's feather, the type used to stuff feather bedding.

Presentation

Although pilonidal disease may manifest as an abscess, a pilonidal sinus, a recurrent or chronic pilonidal sinus, or a perianal pilonidal sinus, the most common manifestation of pilonidal disease is a painful, fluctuant mass in the sacrococcygeal region. Initially, 50% of patients first present with a pilonidal abscess that is cephalad to the hair follicle and sinus infection. Pain and purulent discharge from the sinus tract are present 70-80% of the time and are the 2 most frequently described symptoms. In the early stages prior to the development of an abscess, only a cellulitis or folliculitis is present. The abscess is formed when a folliculitis expands into the subcutaneous tissue or when a preexisting foreign body granuloma becomes infected. The subcutaneous cavity and laterally oriented secondary sinus tract openings are lined with granulation tissue, whereas only the midline natal cleft pit sinus is lined with epithelium.

The diagnosis of a pilonidal sinus can be made by identifying the epithelialized follicle opening, which can be palpated as an area of deep induration beneath the skin in the sacral region. These tracts most commonly run in the cephalad direction. When the tract runs in the caudal direction, perianal sepsis may be present. The distinctions among pilonidal disease, fistula-in-ano, and hidradenitis can be difficult to discern. In the differential diagnosis, also include skin furuncle, syphilitic granuloma, tubercular granuloma, and osteomyelitis of the underlying sacrum with a draining sinus.

Recurrent pilonidal disease is observed most commonly after the incision and drainage of a pilonidal abscess. In this setting, the pilonidal sinus has not been excised and is still present after the abscess cavity heals, only to precipitate a recurrence. After surgical excision, the hair follicle has been removed and is no longer the pathogenic precipitating cause of the chronic pilonidal sinus. Instead, the base of the unhealed surgical wound is believed to become filled with granulation tissue, hair, and skin debris, which is a nidus for the ongoing foreign body reaction that causes the chronic disease. This theory, coupled with the known predisposing intergluteal anatomy that draws hair into the pilonidal sinus cavity or surgical wound, is thought to precipitate the extensive recurrent and chronic disease.

Endoanal pilonidal sinus is a rare variety of pilonidal disease that affects the perianal skin directly or may occur circumferentially around the anus, involving the skin of the anal verge.⁴ Three causes of perianal pilonidal disease have been described. First, the pilonidal sinus may tract down caudally, creating a perianal fissure or fistula communicating with the anal canal. Second, hair may enter the healing wound of a surgically managed fistula-in-ano. Third, hair may be propelled, penetrating the normal anoderm and producing a similar foreign body reaction, which is usually observed in the sacrococcygeal region.

Indications

The ideal treatment for a pilonidal sinus varies according to the clinical presentation of the disease. First, dividing pilonidal disease into 3 categories that represent different stages of the clinical course is important. These 3 categories are (1) acute pilonidal abscess, (2) chronic pilonidal disease, and (3) complex or recurrent pilonidal disease.

The surgical management is then tailored to the classification category. The goals of the ideal procedure for the treatment of this disease should be reliable wound healing with a low risk of recurrence, a short period of hospitalization, minimal inconvenience to the patient, and low morbidity, with few wound-management problems. Also, treatment should allow the patient to resume normal daily activities as quickly as possible.

Relevant Anatomy

A pilonidal sinus can occur in many different areas of the body, but most are found in the sacrococcygeal area, in the natal cleft, approximately 5 cm from the anus. The characteristic pilonidal sinus is a midline opening in the sacrococcygeal area in the natal cleft. Not uncommonly, the patient may have a series of openings in the midline or may have secondary lateral openings superior to the midline pit. The sinus tract itself is smooth and lined with squamous epithelium. Eventually, the sinus tract leads to a subcutaneous cavity lined with granulation tissue and filled with nests of hair. The sinus tract openings are actually an extension of the deep cavity. This is why an abscess formation may present either in the midline or lateral to the midline.

Contraindications

Although no specific contraindications exist for the treatment of pilonidal disease, consider the patient's overall situation and well-being. Certainly, acute infections must be drained, and few, if any, situations exist in which one would choose not to do so. When more extensive procedures are required (eg, in the case of chronic or recurrent pilonidal disease), consider the issue from the perspective of the individual patient. Although definitive surgical solutions to a chronic, smoldering problem may definitely be indicated, they must be undertaken when the patient can afford the requisite downtime necessary for recovery. Also, weigh the complexity of the proposed surgical procedure against the patient's individual comorbidities and long-term prognosis.

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