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Pilonidal Sinus
Etiology
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.
Presentation
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.
Treatment
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.
Pilonidal Abscess
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.
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