Warts

Basics

Description

  • Warts (verrucae) are common, benign, and frequently self-limited epithelial growths caused by human papillomavirus (HPV) infection of keratinocytes.
  • Types of warts
    • Cutaneous
      • Common warts (verruca vulgaris)
      • Flat warts (verruca plana)
      • Plantar warts (weight-bearing)
    • Anogenital
    • Laryngeal (laryngeal papillomatosis)

Epidemiology

Prevalence

  • Cutaneous warts
    • Mostly affect children and young adults
    • Affect girls more than boys
    • 5.3% prevalence from age 6 to 15 years of age
    • Up to 1/3 of school-aged children have had warts.
  • Anogenital warts
    • Exact prevalence in children and adolescents is unknown.
    • Approximately 1% of sexually active adults have external genital warts.
  • Laryngeal warts
    • Rare with no known cure; transmission occurs in utero or through birth canal.

Risk Factors

  • Direct or indirect contact
  • Autoinoculation can cause persistent infection and spread.
  • Use of communal pool surfaces, bathrooms, and shower rooms increases risk.
  • Areas of skin trauma and breakdown have increased susceptibility to HPV infection.
  • Regularly walking barefoot outside also increases risk.
  • Excessive foot perspiration
  • Immunosuppressed patients, particularly transplant patients, are highly vulnerable.
  • Individual susceptibility factors related to developing warts after exposure to HPV are less clear.

General Prevention

  • Cutaneous warts
    • Use protective footwear in warm, moist environments and communal areas.
    • Wear cotton socks and change twice a day, especially if significant perspiration.
    • Avoid sharing nail files.
    • Avoid scratching and nail-biting to prevent autoinoculation.
  • Anogenital warts
    • Avoid sexual contact with multiple partners.
    • Condoms may be protective.
    • Quadrivalent HPV vaccine protects against HPV subtypes 6, 11, 16, and 18.
      • Recommended universally for males and females, ages 9 to 26 years

Pathophysiology

  • Warts are caused by HPV infection of the epithelium.
  • HPV replication leads to cell proliferation and formation of characteristic lesions.

Etiology

  • >150 subtypes of HPV exist.
  • Certain subtypes have a predilection for particular body sites and produce characteristic lesions:
    • Plantar and common palmar warts often caused by HPV 1 and 2
    • Anogenital warts commonly caused by HPV 6, 11, 16, 18, 31, and 45
    • Laryngeal papillomatosis is associated with HPV 6 and 11.

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