Warts

• ANATOMY OR SYSTEM AFFECTED: Genitalia, skin

Definition

Warts are usually painless, harmless growths on the skin caused by a virus that can be disfiguring, embarrassing, and occasionally itchy and uncomfortable. Different types of warts include common warts, which usually appear on hands but can appear anywhere. Flat warts, which usually appear on the face and forehead and are common in children and teenagers but rarely seen in adults. Genital warts, which are usually found on the genitals, in the pubic area, and in the area between the thighs, but can also appear inside the vagina and anal canal. Plantar warts, found on the soles of the feet; and subungual and periungual warts, which appear under and around the fingernails or toenails.

Causes

The typical wart is a raised round or oval growth on the skin with a rough surface caused by a virus. This virus includes dozens of types of the human papillomavirus (HPV).

Risk Factors

Most warts are harmless and are more of a nuisance than a threat. They are caused by low-risk types of HPV, but high-risk types of HPV can lead to cervical cancer. Although not a danger, warts around and under nailscalled periungual wartsare much more difficult to cure than warts elsewhere.

Symptoms

Warts are named by their clinical appearance and location, and different forms are linked to different HPV types. Common warts (verrucae vulgaris) are caused by HPV 1, 2, 4, 27, and 29. They are usually asymptomatic but sometimes cause mild pain, especially when they are located on a weight-bearing surface. Flat warts caused by HPV 3, 10, 28 and 49, are smooth, flat-topped, yellow-brown papules, most often located on the face and along scratch marks. Genital warts manifest as discrete flat to broad-based smooth to velvety papules on the perineal, perirectal, labial, and penile areas. Infection with high-risk HPV typesmost notably 16 and 18is the main cause of cervical cancer.

Screening and Diagnosis

Diagnosis of warts is based on clinical appearance and biopsy is rarely needed. A primary sign of warts is the absence of skin lines crossing their surface and the presence of pinpoint black dots (thrombosed capillaries) or bleeding when warts are shaved. Differential diagnosis includes corns (clavi), lichen planus, seborrheic keratosis, skin tags, and squamous cell carcinomas. DNA (deoxyribonucleic acid) typing is available in some medical centers but is generally not needed.

Some warts will disappear without treatment, although they can sometimes remain for a couple of years. Treated or not, warts that go away often reappear. Genital warts are contagious, while common, flat, and plantar warts are much less likely to spread from person to person. All warts can spread from one part of the body to another. Treatment is often sought because people generally consider warts unsightly and because the appearance of warts is often stigmatized.

Treatment and Therapy

Standard treatment for warts includes freezing (cryotherapy or liquid nitrogen therapy), treatment with cantharidin (a substance extracted from the blister beetle), and minor surgery that may involve cutting away the wart tissue or destroying it by using an electric needle in a process called electrodesiccation and curettage. Some warts may be treated with laser therapy or injections of interferons, antigens, bleomycin, or 5-fluorouracil.

Other possible treatments include self-care approaches such as salicylic acid gels, creams, or patches available at drugstores. Another approach is using duct tape to cover warts for six days, then soaking them in warm water and rubbing them with an emery board or pumice stone. Other therapies include injection with bleomycin or the use of retinoids. However, because some warts are highly contagious, the chosen therapy must be appropriate for the type of wart with consideration of one's lifestyle.

Prevention and Outcomes

Avoiding the following behaviors will help to reduce the risk of getting or spreading warts:

• brushing, clipping, combing, or shaving areas that have warts
• using the same nail clipper on healthy nails that was previously used on warts
• biting fingernails near warts
• picking at warts.

One should also keep hands as dry as possible, wash hands carefully after touching warts, and use footwear in public showers or locker rooms. Avoid sharing towels and washcloths. Some HPV vaccines can prevent warts caused by certain viruses.

Bibliography

Androphy, E. J., et al. “Warts.” In Fitzpatrick’s Dermatology in General Medicine, edited by K. Wolff et al. 7th ed. McGraw-Hill Medical, 2008.

Banks, Rosie. What Are HPV and Genital Warts? Rosen Publishing, 2022.

Berger, T. G. “Dermatologic Disorders.” In Current Medical Diagnosis and Treatment 2011, edited by Stephen J. McPhee and Maxine A. Papadakis. McGraw-Hill, 2011.

Dehghani, F., et al. “Healing Effect of Garlic Extract on Warts and Corns.” International Journal of Dermatology, vol. 44, 2005, p. 612.

Egawa, K., et al. “Topical Vitamin D3 Derivatives for Recalcitrant Warts in Three Immunocompromised Patients.” British Journal of Dermatology, vol. 150, 2004, p. 367.

Kang, Sewon. Fitzpatrick’s Dermatology. 9th ed. McGraw-Hill Education, 2019.

“Warts" Cleveland Clinic, 20 Feb. 2024, my.clevelandclinic.org/health/diseases/15045-warts. Accessed 1 Oct. 2024.

“Warts: Overview.” American Academy of Dermatology, www.aad.org/public/diseases/a-z/warts-overview. Accessed 1 Oct. 2024.