Pilonidal disease is a common infection that occurs around hair-containing sinuses in the natal cleft. It usually presents in young men, and if it is not managed correctly, it tends to persist or recur. The disease and its treatments are a significant burden on patients, caregivers, and society, often resulting in significant loss of time from work with persistent symptoms, a continuing need for wound care, and frequent trips to health care providers for follow-up.
In 1833, Herbert Mayo first described a hair-containing sinus in the natal cleft. Initially thought to be congenital in origin, pilonidal sinus disease is now widely accepted to be an acquired condition that originates when healthy hair penetrates the skin through either a preformed sinus/hair follicle or by creating new sinuses. Subsequently, foreign body reaction, epithelialization of tracts, and chronic infection become the hallmarks of disease, leading either to chronic sinuses or recurring abscesses.
Loose hair, frictional force, and vulnerable skin are the main factors that lead to hair insertion and sinus formation. Contributing risk factors are hirsutism, obesity (a deep natal cleft), a sedentary lifestyle or occupation, and macerated natal cleft skin. Often there is a family history of pilonidal disease.
A pilonidal sinus, which is found within the cephalad aspect of the gluteal cleft, consists of a midline pit (sinus opening) and an epithelium-lined tract. The sinus usually contains hair, and the sinuses lead to a pilonidal cyst cavity within the subcutaneous fat. These cyst cavities are lined by chronic granulation tissue and contain debris and, frequently, hair shafts. Multiple midline pits may be present, as well as secondary openings or fistulae laterally.
The differential diagnosis of natal cleft infection includes hidradenitis suppurativa, Crohn disease, fistula-in-ano, and infected skin furuncles.
Asymptomatic Pilonidal Sinus
Surgery is not recommended for asymptomatic pits. Maintenance of regional hygiene, appropriate weight loss, and consideration of depilation have been promoted, but simple observation is usually all that is required.
A pilonidal abscess requires drainage. Management options ( Fig. 7-1 ) include a midline incision with excision of the central pits (deroofing) or an off-midline incision. Avoiding a wound in the depths of the natal cleft (with its moist, anaerobic environment and ongoing frictional forces) is the preferred option because the alternative leaves a wound in the midline that is more likely to accumulate further loose hairs.
Overall, a midline incision for deroofing and drainage of a pilonidal abscess takes longer to heal and requires more time off work, more dressing changes, and more extensive follow-up, with no proven impact on reducing recurrence compared with an off-midline incision and drainage procedure. An off-midline incision should be placed on the side of any secondary openings within the boundaries of any potential subsequent excisions.
Successful healing can be expected in 60% to 80% of cases after incision and drainage of a first-episode acute pilonidal abscess. If a wound has failed to heal by 10 weeks, it is unlikely to do so. Adding curettage to off-midline drainage removes debris, hair, and the granulation tissue lining the pilonidal cavity. Curettage is associated with an even higher rate of complete healing, as well as lower rates of disease recurrence.
Recurrent disease after complete healing occurs in approximately 10% to 15% of patients. Overall, about 30% to 50% of patients will ultimately require a definitive excisional procedure.
A recent series reviewed the outcomes of patients with simple acute pilonidal abscesses (no skin necrosis, sepsis, diabetes, or immunocompromise) who had their abscess drained via needle aspiration and were discharged the same day with a prescription for oral antibiotics (cephalexin and metronidazole). A total of 95% returned to normal activities, including work, within 24 hours, with no aftercare requirements. The aim was for patients to return for elective surgery, but whereas half underwent formal excision about 7 weeks later, many others had no sign of recurrence at follow-up.
Chronic Pilonidal Sinus
A chronic pilonidal sinus generally occurs after an acute abscess; the source of the infection is the hair-containing subcutaneous cavity. The hair acts as a foreign body and allows the infection to persist and recur. Management ( Fig. 7-2 ) is aimed at removing the hair and the granulations so the source of the infection is gone.
Meticulous regional hair control by shaving, waxing, or laser treatment has been promoted as a conservative nonoperative approach for chronic sinuses, as well as an adjunct to surgical management in an attempt to reduce recurrence. However, more recently a large study revealed a higher rate of disease recurrence over 10 years in patients who obeyed postoperative instructions to regularly shave the region compared with those who didn’t (30.1% vs. 19.7%). Consideration of alternatives such as laser depilation rather than shaving, which may damage the skin and encourage recurrent disease, may be worthwhile.
Lateral Drainage, Curettage, and Midline Pit Excision
Bascom described the simple technique of lateral drainage, curettage, and midline pit excision, similar to Lord and Millar’s midline pit excision and cavity cleansing as described in 1965. A small, vertical off-midline incision centered over the abscess/cyst cavity allows curettage and is left open for drainage. The midline pits are excised, and the 2- to 4-mm excision sites are sutured. The procedure can be performed as day surgery with use of a local anesthetic. In Bascom’s study of 161 patients, only one day of work was missed, no wound dressings were required, and the mean time to complete wound healing was 3 weeks. A 14% recurrence rate was seen, with the majority of recurrences occurring within the mean follow-up of 3.5 years.
A larger study published a variation on Bascom’s “pit-picking” procedure and showed good results. All openings and tracts were cored out with skin trephines (from 2 mm up to 9 mm in diameter). Curved forceps or curettes, as well as cotton swabs dipped in hydrogen peroxide, were introduced via the trephines to clear the cavities of hair, debris, and granulation tissue. All wounds were left open and no packing was needed. The recurrence rate at 5 years was about 13%.
Local Excision and Healing by Secondary Intention
Local excision and healing by secondary intention, a simple and reproducible technique, is widely practiced. It involves regular outpatient visits, initially painful dressing changes, and for patients with larger wounds, a significant time off work. The average healing time is well over 2 months. Marsupialization, by suturing the skin edges to the wound base, was added to wide excision with the goal of creating a smaller wound that will heal more quickly. Negative pressure dressings have been used to facilitate faster healing.
Wounds that are present after excision and primary midline closure heal significantly faster than do wounds that are present after excision without closure. However, after open healing, a recurrence is less likely to occur. When directly compared with midline closure after excision, open healing is associated with an estimated 60% reduction in the risk of recurrent disease.
Local excision and open healing will always be an option in the setting of recurrent disease and sepsis. However, there is no guarantee of success because the patient is still left with a deep natal cleft and vulnerable skin for the duration of the healing process, with the associated risk of recurrence.
Excision and Wound Closure: Midline or Off-Midline Closure?
If excisional surgery is required for chronic pilonidal disease, the one principle that provides a clear benefit is to close the wound off the midline rather than directly in the midline of the gluteal cleft. Wounds off the midline have consistently been associated with faster healing times and lower rates of wound morbidity and recurrence. For studies with follow-up longer than 12 months, the recurrence rate for off-midline closure was 1.4%, compared with 10.3% with midline closure. Nine patients would need to be treated with excision and off-midline closure to prevent one wound infection, and 11 would need to be treated in this manner to prevent one recurrence.