Pilonidal Cyst

Aka: Pilonidal Cyst, Pilonidal Sinus, Pilonidal Abscess, Pilonidal Disease

1. Epidemiology
   1. Incidence: 70,000 cases in U.S. per year
   2. Infection occurs most often in males, age 16 to 30 (uncommon after age 40 years)
2. Risk Factors
   1. Men (more common by 3 fold over women)
   2. Caucasian (more than asian or black patients)
   3. Hirsutism (especially in the gluteal cleft)
   4. Obesity
   5. Local Trauma
3. Pathophysiology
   1. Pit forms at skin disruption in gluteal fold (may be injured by embedded loose hairs)
   2. Pit plugs with hair and keratin
   3. Pilonidal Cysts form when drainage of pit is blocked, and abscess forms when infected
   4. Sinus tracts may also develop
4. Symptoms
   1. Pain in gluteal fold
   2. No systemic symptoms
5. Signs
   1. Midline tender, erythematous swelling in the gluteal fold over Coccyx or Sacrum
   2. Abscess forms at the upper gluteal cleft
      1. Contrast with perianal fistula which is adjacent to the anus
      2. Pilonidal Abscess and sinus tracts do NOT communicate with anorectal region
6. Differential Diagnosis
   1. Hidradenitis Suppurativa
   2. Skin Furuncle or Skin Abscess
   3. Crohn Disease
   4. Perianal fistula
   5. Perianal Abscess
   6. Perirectal Abscess
   7. Squamous Cell Skin Cancer
7. Management: Pilonidal Disease without Abscess
   1. Hair removal from the gluteal cleft
      1. Weekly shaving
      2. Consider laser Epilation
      3. Topical phenol helps prevent recurrence
      4. Fibrin glue (with or without surgical excision - see below)
8. Management: Pilonidal Abscess
   1. Incision and Drainage under Local Anesthesia
      1. Wear Personal Protective Equipment (including mask)
      2. Prepare the skin in typical fashion (Povidone Iodine or Chlorhexidine and draped)
      3. Lidocaine with Epinephrine local Anesthetic
      4. Make small incision lateral to midline (#11 or #15 Blade)
         1. Do not make incision in midline (risk of non-healing)
      5. Drain the abscess and break up adhesions with hemostat
      6. Wound packing is recommended for larger abscesses for the first 48 hours
      7. Apply a bulky, absorbent dressing
   2. Antibiotic Indications
      1. Surrounding Cellulitis
      2. Immunocompromised patients
   3. Wound care
      1. Patients should start with sitz baths at 24 hours after Incision and Drainage
   4. Consider surgical referral for cyst and sinus excision
      1. Routine surgical Consultation is typically recommended due to the high recurrence rate
      2. Many surgical approaches exist (e.g. marsupialization, Healing by Secondary Intention, flap closure)
      3. See recurrence rates below
9. Complications
   1. Pilonidal Abscess (surrounding Cellulitis may be present)
   2. Pilonidal Sinus Drainage
   3. Recurrent infections: 10 to 55%
      1. Abscess often recurrs in the same location
10. References
    1. Marx (2002) Rosen's Emergency Medicine, p. 1952
    2. Sherman, Bahga and Vietvuong (2022) Crit Dec Emerg Med 36(7): 23-9
    3. Johnson (2019) Dis Colon Rectum 62(2): 146-57 [PubMed]