Makindo Medical Notes

🌀 Pilonidal sinus disease is an acquired, chronic inflammatory condition of the skin and subcutaneous tissue in the sacrococcygeal (natal cleft) region.

📖 About

• Caused by ingrowth of hairs into a sinus in the buttock cleft.
• The term pilonidal means “nest of hairs” (Latin: pilus = hair, nidus = nest).
• Incidence: ~26 per 100,000 population, peak in young adults.

⚠️ Aetiology & Risk Factors

• Trapped hairs → foreign body reaction → infection.
• Post-puberty hormonal changes increase risk.
• 👨 Most common in men, aged 18–30.
• 🦵 Dark-haired, hirsute individuals.
• 💺 Sedentary lifestyle, prolonged sitting (drivers, office workers).
• Interdigital variant seen in hairdressers (“barber’s sinus”).

🩺 Clinical Features

• Young adults (15–30) most affected.
• Typical site: natal cleft ~5 cm above anus.
• Pain, swelling, erythema; may form a tender abscess.
• Recurrent discharge of pus or blood from midline pits.
• Chronic disease → multiple sinus openings with granulation tissue.
• Occasionally causes systemic upset if abscess large/infected.

🔎 Investigations

• Bloods: FBC (infection), CRP, U&E, LFTs, Glucose.
• Rigid sigmoidoscopy or MRI if suspicion of deeper tracts or internal opening.

🧬 Pathology

• Keratin blocks follicle → folliculitis and oedema.
• Sinus forms with retained hair/debris, gradually forming abscess cavity.
• Chronic inflammation → epithelialised tracts.
• Rare complication: osteomyelitis of sacrum/coccyx.

💊 Management

• Prevention:
  • Meticulous perianal hygiene, daily showers.
  • Regular buttock hair removal: shaving, depilatory creams, waxing.
  • Laser hair removal has lower recurrence compared with shaving.
  • Weight loss and avoiding prolonged sitting.
• Acute abscess: Incision & drainage ± curettage to remove hairs and debris, pack cavity. Small, superficial lesions may be managed in primary care if expertise available; otherwise, refer to general/colorectal surgery.
• Recurrent disease:
  • Karydakis procedure (flap repair to flatten natal cleft).
  • Bascom cleft lift or Limberg flap for recurrent/complex cases.
• Definitive: En bloc excision in severe/refractory cases.
• Adjunct: antibiotics only if spreading cellulitis or systemic sepsis.

⚠️ Exam Pearls

• Think of pilonidal sinus in a young male with a tender lump/discharge in the natal cleft.
• Hairdressers can get interdigital pilonidal sinus (“barber’s sinus”).
• Recurrence is common if hair removal and hygiene not maintained.

📚 References

• Understanding Pilonidal Sinus Disease – WWIC
• NICE CKS: Pilonidal Sinus

Case examples

• 🧍‍♂️ Case 1 – Age 24: University student presented with severe pain and swelling at the top of the buttock cleft for three days. Examination revealed a tender, fluctuant mass with purulent discharge from a midline pit. Diagnosis: Acute pilonidal abscess. Management: Incision and drainage under local anaesthetic, with wound left open to heal by secondary intention. Teaching point: Acute pilonidal abscesses are caused by infection of hair-containing sinus tracts in the natal cleft, commonly in young hirsute men who sit for long periods.
• 💻 Case 2 – Age 33: IT worker with a history of recurrent swelling and intermittent discharge from the sacrococcygeal area for over a year. No fever but persistent discomfort when sitting. Diagnosis: Chronic pilonidal sinus with secondary tracts. Management: Elective excision and off-midline flap closure (Karydakis procedure) to prevent recurrence. Teaching point: Recurrent disease requires surgical excision and attention to hygiene, hair removal, and weight control to reduce recurrence risk.
• 🏃‍♀️ Case 3 – Age 19: Athletic female reported pain and redness near the coccyx after a long cycling trip. Examination showed local cellulitis but no obvious abscess. Ultrasound confirmed a small collection near a sinus opening. Diagnosis: Early pilonidal abscess. Management: Short course of antibiotics, warm compresses, and surgical review for possible drainage if symptoms worsened. Teaching point: Early recognition and conservative management can prevent abscess formation, particularly in physically active individuals with friction and sweating in the natal cleft.