Warts

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Basics

  • Warts (verrucae) are benign growths that are confined to the epidermis. All warts are caused by the human papillomavirus (HPV). Warts can appear on any area of the skin or mucous membranes. Common warts are predominantly seen in children and young adults.
  • Clinically, warts are described as follows:
    • Common warts (verrucae vulgaris)
    • Plantar warts (verrucae plantaris)
    • Flat warts (verrucae plana)
    • Genital warts (condyloma acuminatum)
    • Epidermodysplasia verruciformis is a rare, lifelong hereditary disorder characterized by chronic infection with HPV.
  • System(s) affected: skin/exocrine

Description

  • Common warts are most often found at sites subject to frequent trauma, such as the hands and feet. Because warts often vary widely in shape, size, and appearance, the various descriptive names for them generally reflect their clinical appearance, location, or both.
  • For example: Filiform (fingerlike) warts are threadlike, planar warts are flat, and plantar warts are located on the plantar surfaces (soles) of the feet.
  • Genital warts, or condyloma acuminata, may be large and cauliflower-like, or they may consist of small papules.
  • Warts on mucous membranes (mucosal papillomas), such as those in the mouth or vagina, tend to be white in color due to moisture retention.

Epidemiology

Incidence
  • Predominant age: young adults and children
  • No sex predominance: female = male

Prevalence
  • ~7–10% of the U.S. population
  • Common warts appear 2 times as frequently in whites compared with blacks or Asians.

Etiology and Pathophysiology

  • HPV is a double-stranded, circular, supercoiled DNA virus.
  • The virus infects epidermal keratinocytes, stimulating cell proliferation.
  • Various strains of DNA HPV: To date, >150 different subtypes have been identified.
  • Common warts: HPV types 2 and 4 (most common), followed by types 1, 3, 27, 29, and 57
  • Palmoplantar warts: HPV type 1 (most common), followed by types 2, 3, 4, 27, 29, and 57
  • Flat warts: HPV types 3, 10, and 28
  • Butcher warts: HPV type 7
  • The virus is passed primarily through skin-to-skin contact or from the recently shed virus kept intact in a moist, warm environment.

Risk Factors

  • HIV/AIDS and other immunosuppressive diseases (e.g., lymphomas)
  • Immunosuppressive drugs that decrease cell-mediated immunity (e.g., prednisone, cyclosporine, and chemotherapeutic agents)
  • Pregnancy
  • Handling raw meat, fish, or other types of animal matter in one’s occupation (e.g., butchers)
  • Previous wart infection

General Prevention

There is no known way to prevent warts.

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