Warts are benign proliferations of the skin and mucosa caused by human papilloma virus (HPV) infection. They can grow on all body parts including the face, fingers, feet, legs, hands, knees, inside your mouth, and on the genital and rectal areas.
Warts are particularly common in childhood (affecting approximately 15% of school aged children), but may arise at any age. They are spread by direct contact or autoinoculation with a latency of weeks to years. Warts may also spread by using towels or other personal items which have been used by a person with warts. Warts can bleed if picked or cut and can cause pain, especially plantar warts.
Subtypes favor particular sites, but can appear at any site. Subtypes include:
- Common warts: hard papule with dry surface most often on hands and knees
- Filiform warts: long this lesions most often on the face
- Palmoplantar warts: round horny deep painful nodules, most often on weight-bearing sites
- Mosaic warts: closely grouped, generally presenting as plantar warts
- Periungual warts: warts arising around nails and nail folds
- Flat warts: smooth or dry small papules, often numerous, and found on the face, hands, and shins; can spread with scratching and shaving
- Genital warts: often transmitted sexually
Warts are often diagnosed by simple observation of the lesions. It may be helpful to pare the surface to reveal small black dots, which are clotted blood vessels at the surface of the wart. Occasionally a biopsy may be necessary to confirm the diagnosis.
Warts can resolve without treatment, but may take months or even years to disappear. If warts are symptomatic (painful, itchy) or spreading, they should be treated. Clearance often requires multiple in-office treatments, in conjunction with at-home patient treatment as well.
Treatment options include:
- Daily at-home application of topical agents containing salicylic acid.
- Occlusion with adhesive plaster or duct tape.
- Regular paring using a scalpel blade.
- Cryotherapy with liquid nitrogen to wart and 1-2 mm rim of surrounding normal tissue. The depth of freeze should be sufficient to cause a little blistering and should be repeated every 2-4 weeks on 4-6 occasions.
- Electrosurgery (curettage & cautery), used for particularly large and annoying warts. Under local anaesthetic, the growth is pared away and the base burned by cautery. The wound heals in about two weeks; however 20% of warts can be expected to recur within a few months. The procedure is painful and often leaves a scar.
- Cantharone, a medicine derived from the Japanese blister beetle, can be applied to warts; causes a blister/local destruction at each site.
- A topical immunomodulator cream can be prescribed; when applied to warts, it causes your immune system to release cytokines to attack the HPV virus.