Warts

Medical Dermatology

Skin Conditions

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Warts are non-cancerous skin growths caused by a viral infection in the top layer of the skin. Viruses that cause warts are called human papillomavirus (HPV). Warts are usually skin-colored and feel rough to the touch, but they can be also be dark, flat and smooth. The appearance of a wart depends on where it is growing.

Common warts usually grow on the fingers, around the nails and on the backs of the hands. They are more common where skin has been broken, for example where fingernails are bitten or hangnails picked. Many people call these "seed" warts. The blood vessels to the wart produce black dots that look like seeds.

Plantar warts are usually on the soles of the feet. When plantar warts grow in clusters they are known as mosaic warts. Most plantar warts do not stick up above the surface like common warts because the pressure of walking flattens them and pushes them back into the skin. Like common warts, these warts may have black dots. Plantar warts can be painful, feeling like a stone in the shoe. Flat warts are smaller and smoother than other warts. They tend to grow in large numbers - 20 to 100 at any one time. They can occur anywhere, but in children they are most common on the face. In adults they are often found in the beard area in men and on the legs in women. Irritation from shaving probably accounts for this.

Warts are passed from person to person, sometimes indirectly. The time from the first contact to the time the warts have grown large enough to be seen is often several months. The risk of catching hand, foot, or flat warts directly from another person is small.

Some people get warts depending on how often they are exposed to the virus. Wart viruses occur more easily if the skin has been damaged in some way, which explains the high frequency of warts in children who bite their nails or pick at hangnails. Some people are just more likely to catch the wart virus than are others and their immune system may simply not recognize the virus as an infection to be fought.

In children, warts can disappear without treatment over a period of several months to years. However, warts that are bothersome, painful, or rapidly multiplying should be treated. Warts in adults often do not disappear as easily or as quickly as they do in children.

Dermatologists are trained to use a variety of treatments, depending on the age of the patient and the type of wart. Warts in young children can be treated at home by their parents on a daily basis by applying salicylic acid gel, solution or plaster. There is usually little discomfort and it can take many weeks of treatment to obtain favorable results. Treatment should be stopped at least temporarily if the wart becomes sore. Warts may also be treated by "painting" with cantharidin in the dermatologist's office. Cantharidin causes a blister to form under the wart. The dermatologist can then clip away the dead part of the wart in the blister roof in a week or so.

For adults and older children cryotherapy (freezing) is generally preferred. This treatment is uncomfortable but generally tolerated well and it rarely results in scarring. However, repeat treatments at one to three week intervals are often necessary.

Flat warts are often too numerous to treat with methods mentioned above. As a result, "peeling" methods using daily applications of salicylic acid, tretinoin, glycolic acid or other surface peeling preparations. For some adults, periodic office treatments for surgical treatments are sometimes necessary. There are several different lasers used for the treatment of warts. Laser therapy is used to destroy some types of warts. Another treatment is to inject each wart with an anti-cancer drug called bleomycin. The injections may be painful and can have other side effects. Topical anti-cancer drugs may be used and immunotherapy, which attempts to use the body's own rejection system is another method.

Many people, patients and doctors alike, believe folk remedies are effective. Since warts, especially in children, may disappear without treatment, it's hard to know whether it was a folk remedy or just the passage of time that led to the cure. Since warts are generally harmless, there may be times when these treatments are appropriate. Medical treatments can always be used if necessary. Sometimes it seems as if new warts appear as fast as old ones go away. This may happen because virus has been shed into the surrounding skin. The best way to limit this is to treat new warts as quickly as they develop so they have little time to shed virus into nearby skin. A check by your dermatologist can help assure the treated wart has resolved completely.

Research is moving along very rapidly. There is great interest in new treatments, as well as the development of a vaccine against warts. We hope there will be a solution to the annoying problem of warts in the not too distant future.