A wart is a benign neoplasm of epidermal cells caused by infection with certain strains of human papillomaviruses (HPV). The have a verrucous or “warty’ appearance that results from epidermal thickening, scale, and prominence of the dermal papillae. Warts are common in children and young adults. Sexually active adults may have genital warts, which are caused by a different strain of the human papillomavirus. There are a number of varieties of warts that can be distinguished based on physical exam.
Common wart (verruca vulgaris). The common wart is a flesh-colored, scaling papule. It interrupts skin lines and has black puncta. They commonly occur on the hands and digits. Groups of warts may be found, sometimes in linear arrangements; this is the result of autoinnoculation (infecting oneself).
Flat wart. A flat wart is a minimally raised, flesh-colored, reddish or brown papule. They are typically found on the hands and face, and multiple lesions are often present.
Plantar wart. Plantar warts are densely callused lesions that occur on the plantar (bottom) aspect of the foot; the “warty” nature can be best visualized by paring down the callus. They are often painful.
Condyloma acuminatum. These are genital, or venereal, warts. They affect the external genitalia, perineal region, inguinal folds, and sometimes the vagina or urethra. Lesions appear as fleshy moist papules with a classic verrucous appearance.
With what can a wart be confused?
The differential diagnosis depends on the type of wart. A common wart is usually easily diagnosed based on clinical appearance. It can resemble a corn. Non-healing, crusted or ulcerated lesions should prompt suspicion of squamous cell carcinoma. A flat wart, when reddish, can occasionally be confused with the purple lesions of lichen planus. Plantar warts can easily be confused with a corn. Condyloma acuminatum, genital warts, must be distinguished from condyloma lata (a lesion of secondary syphilis), and from squamous cell carcinoma and bowenoid papulosis (a form of in situ squamous cell carcinoma).
How is a wart diagnosed?
Most warts are diagnosed clinically; biopsy is usually not warranted.
For genital warts, soaking the area in 5% acetic acid (vinegar) for several minutes causes the warts to turn white; however, this is not a recommended practice, since this test is not very specific for warts.
How is a wart treated?
The treatment for a wart is physical, chemical or biological destruction of the infected epidermal cells of the lesion. The most commonly employed physical modalities are liquid nitrogen cryotherapy, electrodessication and curretage, surgical excision, and laser ablation. Chemodestructive agents can be applied by a physician in the office or by the patient at home. Common warts can be treated with trichloroacetic acid, salicylic acid, and cantharidin. Plantar warts are best treated with salicylic acid. Condyloma acuminatum can be treated with topical podophyllin, but this agent is very toxic and its use is not preferred. A less-toxic derivative, podofilox, is available for home use as Condylox. Flat warts often respond to retinoids (Retin-A). Resistant warts may respond to the chemotheraputic agent bleomycin, interferon, or 5-flurouracil, either topically or intralesionally (or very rarely systemically). Biological approaches stimulate a host immune response to the viral infection and eradication of the infected cells. Imiquimod (Aldara) is the agent most commonly used in this fashion. Elicitation of contact dermatitis by other means, such as poison ivy resin or squaric acid, is also used. Laser destruction, often with a laser that targets the wart’s blood supply such as a pulsed dye laser, is a commonly used treatment, as is ablation with a CO2 laser.
What is the prognosis for a wart?
Probably the majority of warts regress spontaneously within two years, and approximately 80% can be cured with treatment. Scarring may occur as a result of physical destruction or surgical excision.
Certain strains of HPV are linked to the development of cervical cancer, but these are not the strains that cause skin warts; there is now a vaccine available for the prevention of infection with certain strains of HPV.
Wart treatment at SOMA Skin & Laser