Warts are benign proliferations of skin and mucous membranes caused by the human papillomavirus (HPV). Warts are transmitted by direct or indirect contact, and the most important predisposing factor is disruption of the normal epidermal barrier (wound, eczema). Nonetheless, the risk of contracting warts from a person is very low. After initial exposure to a wart-causing virus, it may take as many as two to six months for the initial onset of warts to occur. It is important to note that warts can spread locally to other areas on your own body (auto-inoculation) through open wounds and nail biting.
Infection with HPV is confined to the epithelium and does not result in systemic or blood stream dissemination of the virus.
Treatment can be difficult, with frequent failures and recurrences. Warts may resolve spontaneously within a few years.
A small subset of HPV types is associated with the development of malignancies, including types 6, 11, 16, 18, 31, and 35. Malignant transformation most commonly is seen in patients with genital warts and in immunocompromised patients.
Types of Warts
Four most common types of warts include:
- Common warts – Common warts also are termed verruca vulgaris. They appear as hyperkeratotic, scaly papules with a rough, irregular surface. They range from smaller than 1 mm to larger than 1 cm. They can occur on any part of the body but are seen most commonly on the hands and knees.
- Palmar and plantar warts – Warts that affect the bottom of the feet and on hands. Plantar warts may be very painful.
- Flat warts – Smaller, smoother warts that typically appear in greater numbers on the face and legs.
- Genital warts – warts affecting genital mucosa.
The subtype of warts may dictate the type of wart removal that is most appropriate for treating your condition.
Treatment options for warts include:
- Cryotherapy (Cryosurgery): Very common treatment in which Liquid Nitrogen is used to “freeze” and destroy affected skin. Treatment often results in blisters which gradually crust and heal in 2-3 weeks. Warts may often require a few treatments before complete resolution. Lesions that are on the palms or bottom of the feet tend to be more resistant and may require multiple treatments.
- Cantharidin: Chemical derived from a type of beetle which is applied to the skin and results in blistering and destruction of the affected area. Similar to cryotherapy, blisters gradually crust and heal in 2-3 weeks.
- Electrosurgery: Electrical current is used to destroy the lesion.
- Surgical excision: The lesion is anesthetized and surgically excised. Often reserved for larger or hard-to-treat warts.
- Bleomycin injection: Chemotherapy injection which is injected into the lesion and causes direct destruction of the affected area.
- Cantharidin injection: Yeast extract which is injected into the skin. Works by drawing the body’s immune system to the wart, helping the body fight the wart. Results may vary.
- Imiquimod cream: A topical cream that helps the body’s immune system fight the wart. Often a good treatment option for genital warts. Side effect includes inflammation and irritation of the skin.
- Salicylic acid: Over-the-counter and prescription-strength salicylic acid preparations can be applied directly to warts which cause resolution and peeling of the lesion. Often requires multiple daily treatments.
- Photodynamic Therapy (PDT) with topical 5-aminolevulinic acid applied to the warts, followed by photoactivation with red 633-nm light-emitting diodes at 2- to 3-week intervals resulted in 68% improvement.
Watchful waiting with providing no treatment can be considered as a treatment option, since 65% of warts may regress spontaneously within 2 years. Without treatment, however, patients risk warts that may enlarge or spread to other areas. Treatment is recommended for patients with extensive, spreading, or symptomatic warts or warts that have been present for more than 2 years.