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

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.