Pilonidal sinus

Definition/diagnostic criteria Pilonidal sinus is a chronic skin condition characterised by the development of a sinus tract or cavity in the natal cleft, near the top of the buttocks. The condition is believed to arise due to the penetration of loose hairs into the skin, leading to a foreign body reaction and subsequent inflammation, abscess formation and sinus tract development.

Epidemiology Pilonidal sinus predominantly affects young adults between the ages of 15 and 40, with a peak incidence in the late teens and early twenties. The condition is more common in males, with a male-to-female ratio of 3:1. Other risk factors include a sedentary lifestyle, obesity, hirsutism and a family history of pilonidal disease.

Clinical features: Patients with pilonidal sinus commonly present with pain, swelling and redness in the natal cleft area. There may be discharge of pus or blood from the sinus tract and, in some cases, multiple sinus openings may be visible. The condition can be complicated by the development of an abscess, cellulitis or fistula. Acute abscesses are associated with severe pain, fever and malaise, while chronic sinus tracts may have minimal symptoms.

Investigations: Diagnosis is primarily clinical, based on the characteristic location and appearance of the lesion, as well as the patient’s symptoms. In cases where the diagnosis is uncertain, or if there are atypical features suggesting an alternative diagnosis (such as Crohn’s disease or malignancy), further investigations may be warranted. These can include ultrasound, MRI, or biopsy of the lesion.

Treatment The treatment of pilonidal sinus depends on the severity and chronicity of the condition.

  • For acute abscesses, incision and drainage are usually required, along with analgesia and advice on wound care.
  • Antibiotics are not routinely recommended unless there are signs of systemic infection or cellulitis.
  • For chronic sinus tracts, the aim of treatment is to prevent recurrence and manage symptoms. Options include conservative management with regular hair removal and good hygiene, or surgical intervention to excise the sinus tract.
  • Various surgical techniques can be used, including wide excision with primary closure, or more minimally invasive procedures such as sinus tract excision or endoscopic pilonidal sinus treatment (EPSiT).

Prognosis The prognosis of pilonidal sinus is generally good, particularly with appropriate management. However, the condition is associated with a high recurrence rate, particularly after surgical treatment. Chronic pilonidal sinus can significantly impact a patient’s quality of life, leading to pain, abscess formation and time off work. Prompt diagnosis and appropriate management are crucial to improve outcomes and reduce the risk of complications.


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