Warts result from infection of the skin and mucous membranes by human papilloma virus (HPV). Warts can appear anywhere on the body. Infection by the HPV virus causes a reaction in the skin that results in thickening of the skin, or hyperkeratosis. Infected skin becomes thickened and firm, resulting in a raised and hardened bump that can be smooth or rough in texture.
In most cases, a biopsy is not needed to make a diagnosis, and a tissue sample is only obtained if there is concern for a serious condition like skin cancer. Warts are not cancerous growths, but they may be uncomfortable or unsightly. Warts that develop on the soles of the feet are known as plantar warts, and they can be painful.
There is no effective treatment specifically targeted at the human papilloma virus itself, so treatments focus on the destruction of infected tissue or enhancement of the immune system’s ability to fight of the viral infection. When tissue destruction is used to treat a wart, the virus can remain present in surrounding tissue. If any infected tissue remains, the wart may recur. It is difficult to predict how many treatments will be required to successfully treat a wart.
Salicylic acid and trichloracetic acid treatment are effective therapies
Warts can be destroyed by application of liquid nitrogen or an acid preparation to the skin. Salicylic acid is a commonly used weak acid preparation that is sometimes effective for treatment of warts. It is available in a liquid, a film, or a patch. Trichloracetic acid is a stronger acid that is generally applied by a dermatologist after shaving the surface of the wart. It is applied in pricks, using a wooden toothpick, and treatments usually occur at intervals of seven to ten days. Use of salicylic acid between treatments with trichloracetic acid may result in more rapid resolution of the wart.
Liquid nitrogen therapy destroys warts by freezing affected tissue
Liquid nitrogen destroys warts by freezing the tissue. It must be applied cautiously to avoid damage to adjacent tissue. Treatment can result in a range of reactions, from minimal redness to blistering, pain, and tenderness. All of these reactions are considered normal. If you develop a blister, your doctor will prescribe a petrolatum preparation like Vasoline® in order to protect the area after your blister pops. The treated area usually heals in four to seven days. Use of salicylic acid after treatment with liquid nitrogen can reduce the risk of recurrence.
Liquid nitrogen treatment may result in an area of lighter skin tone. This can be very noticeable in patients with darker skin tones, so your dermatologist may recommend another treatment if you have a dark complexion. We recommend that patients return for evaluation two or three weeks after their treatment. Repeat treatment in necessary in some patients, and we may recommend additional treatment even when the skin appears normal, in order to eradicate all potentially infected areas.
Topical medications include cantherone and Aladara®
There are a variety of topical medications available for treatment of warts. These medications must be consistently applied to the skin several times a day in order to be effective. Treatment may last several weeks. Cantherone is an effective treatment that is applied to the skin for one to four hours before washing it off. It results in blistering and destruction of the abnormal tissue.
Aldara® is a topical medication that enhances your body’s immune response to abnormal cells. It is used to treat a variety of skin conditions, including some skin cancers.
Bleomycin injections are used to treat resistant warts
Bleomycin is a chemotherapy medication that is injected directly into the wart. It works by killing the affected skin cells, stopping growth. Bleomycin can be painful to inject, so it is usually recommended for patients who have tried other therapies without success.
Pulsed dye lasers or carbon dioxide lasers destroy abnormal tissue with concentrated light beams
Pulsed dye lasers or carbon dioxide lasers can be used to destroy warts that are resistant to other treatments. Lasers are sometimes used for treatment of large warts or treatment of multiple warts spread over a large area.
Laser treatment works by producing heat in tissues that are targeted by the concentrated laser beam. A pulsed dye laser targets hemoglobin, a molecule in the red blood cells, and seals the blood vessels in the wart. This prevents nutrients from reaching the wart, causing the wart tissue to die and drop off.
Carbon dioxide lasers are more destructive than pulsed light therapy. They deliver a highly concentrated light beam, and have been shown to be very effective for treatment of resistant warts and for prevention of recurrence.
Treatment of warts can limit spread of infection and development of new warts
Two-thirds of warts may spontaneously resolve within two years, but most patients prefer to treat warts early. There is a risk of development of new warts in patients who are not treated. People with warts can infect others with the highly contagious HPV, so if you develop warts, it’s important to take precautions to avoid spreading the virus to your contacts.