Cutaneous warts

Cutaneous warts are common benign cutaneous lesions caused by the skin-to-skin transmission of human papillomavirus (HPV). Types include common warts, flat warts, plantar warts, and filiform warts. Cutaneous warts appear as solitary or multiple skin-colored hyperkeratotic exophytic papules or plaques. Lesions are typically asymptomatic but sometimes cause pain or discomfort. Diagnosis is clinical; pinpoint dots on the surface of the lesions that bleed on shaving are a characteristic feature. Biopsy may be considered if there is diagnostic uncertainty. Most cutaneous warts resolve spontaneously within two years, but recurrence is common. Initial management options include watchful waiting, topical salicylic acid, or cryotherapy. Options for refractory warts include electrocauterization, photodynamic therapy, topical immunotherapy, and intralesional injections.

See also “HPV infection” and “Anogenital warts.”

• Most common in children and young adults ^[1]
• Prevalence: ∼ 7–12% ^[2]
• Sex: ♀ = ♂

Epidemiological data refers to the US, unless otherwise specified.

• HPV types that infect the cutaneous epithelium, e.g.: ^[1]
  • Common warts and plantar warts: HPV types 1–4, 27, and 29
  • Flat warts: HPV types 3, 10, 28, and 29
• Transmission: direct skin contact (including autoinoculation) or fomites ^[1]

Warts manifest as discrete or grouped lesions, and the distribution is often more extensive in individuals with underlying immunodeficiency. ^[3]

Common warts (verrucae vulgaris) ^[1][3]

• Skin-colored or gray-brown exophytic papules or plaques (verrucous lesions)
• Hyperkeratotic, rough surface
• May contain red, brown, or black dots
• Located on the hands, knees, and/or face
• Usually painless ^[4]

Flat warts (verrucae planae) ^[1][3]

• More common in children than adults
• Yellow-brown papules with a smooth, flat surface
• Typically occur on face, back of the hands, and shins ^[5]
• Scratching can cause a linear distribution. ^[5]
• Usually painless. ^[4]

Plantar warts (verrucae plantares) ^[1][3]

• Hyperkeratotic papules or plaques on the soles of the feet ^[5]
• Small black dots may be visible on the surface.
• Multiple warts may become confluent (a mosaic wart). ^[3]
• Can be painful

Filiform warts ^[4]

• Single or multiple finger-like projections from a narrow base ^[3][5]
• Most commonly seen on the face and/or neck

• Diagnosis is typically clinical. ^[4]
• Dermoscopy can show red, brown, or black dots. ^[3]
• Shaving the surface of the wart causes bleeding. ^[1][6]
• Consider biopsy if there is diagnostic uncertainty. ^[3]

• Callus
• Corn
• Molluscum contagiosum
• Syringoma
• Seborrheic keratosis
• Actinic keratosis
• Keratoacanthoma
• Cutaneous squamous cell carcinoma

The differential diagnoses listed here are not exhaustive.

General principles

• Consider watchful waiting, as most warts resolve within two years. ^[1]
• Indications for treatment include: ^[1]
  • Discomfort
  • Patient preference and cosmesis
  • Immunosuppression
  • Refractory warts
• Educate patients on prevention of cutaneous warts to reduce autoinoculation.

First-line options ^[1][7]

• Topical salicylic acid (avoid on the face) ^[1][3]
• Cryotherapy
  • Can be painful
  • Requires multiple sessions (repeated every 2–4 weeks, max. 6 sessions) ^[1][6]
  • Consider topical salicylic acid between sessions. ^[6]

Avoid topical salicylic acid on the face because of the risk of pigmentation changes. ^[1]

Options for refractory warts ^[1][6]

Refer patients with refractory warts to dermatology. The following treatments may be considered, although there is limited evidence to support their efficacy.

• Photodynamic therapy
• Topical immunotherapy or antiproliferative agents
• Intralesional injection of bleomycin, bivalent or quadrivalent HPV vaccine, or Candida or mumps skin antigen ^[1][8]
• Laser therapy
• Electrocauterization or curettage

Recurrence is common. Combination therapy or multiple treatments are often required. ^[4]

To prevent aerosolized transmission of HPV to the upper respiratory tract, electrocauterization of warts should be performed in an adequately ventilated area with appropriate PPE (e.g., N95 or above grade respirator). ^[9]

• Use protective footwear in public areas (e.g., locker rooms, public showers). ^[10]
• Avoid direct contact with warts and sharing personal items.
• To minimize risk of spreading infection and autoinoculation: ^[3][10]
  • Cover cutaneous warts
  • Avoid scratching or shaving warts