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Warts

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Updated June 02, 2014

Warts are actually benign tumors of the epidermis caused by a virus. The virus responsible is the human papillomavirus (HPV), a double-stranded DNA virus. The virus resides in the bottom layer of the epidermis and replicates into almost normal-looking skin. Different sub-types of HPV cause different types of warts. Some human papillomavirus subtypes also cause cervical cancer and other more obscure types of wart-related cancers.

The Wart Root Myth
Contrary to popular belief, warts do not have "roots". They only grow in the top layer of skin, the epidermis. When they grow down, they displace the second layer of skin, the dermis. They do not grow into the dermis. The underside of a wart is actually smooth.

The Appearance of Warts
Warts normally grow out of the skin in cylindrical columns. These columns do not fuse when the wart grows on thin skin such as the face. On thicker skin, the columns fuse and are packed tightly together giving the surface the typical mosaic pattern. Black dots can sometimes be seen in a wart. These are actually blood vessels that have grown rapidly and irregularly into the wart and have thombosed or clotted off.

Pictures of Warts
The following pictures show various types of warts:

Who Gets Warts?
Warts can occur in people of all ages, but occur most commonly in children and young adults. They spread by direct contact, simply by touching the wart. Warts normally resolve spontaneously but the time it takes for this resolution is variable. Most warts resolve within weeks or months, but some may take years. It appears that a person's susceptibility to warts and the time it takes for them to go away is related to the individual's immune system. People who have immune-related diseases such as AIDS and lymphoma, or who are taking chemotherapy tend to have more warts that last longer.

Wart Treatments
Most warts can be treated with simple over-the-counter remedies. For those that are resistant to these measures, other types of treatments are effective.

Salicylic acid is a very common and effective over-the-counter treatment, but requires consistent application every day. They best way to use salicylic acid is to first pare the wart with a blade, pumice stone, emory board, or small scrub brush. Soaking the wart in warm water will aid in the absorption of the medicine. Salicylic acid is applied to the wart and allowed to dry. Normal surrounding skin may be protected with petroleum jelly. Occluding the treated wart with a band-aid or piece of tape also improves the absorption of the medicine. This procedure should be repeated daily ideally around shower or bath time. Salicylic acid can be found in several forms including a thick oil, or incorporated into an adhesive plaster form.

Cryotherapy is another effective treatment of warts. A provider applies liquid nitrogen as a spray or on a cotton swab to the wart. This freezes and kills the effected cells. The connective tissue is not destroyed; therefore, the lesion usually heals without significant scarring. The human papillomavirus is not killed by cryotherapy and is released into the surrounding tissue allowing the immune system to kill it. A blister typically forms on the site treated, crusts over, and falls off. Since blisters are painful to walk on, cryotherapy is not a first choice for warts on the bottom of the foot.

Other medicines may be applied to warts or injected into them include lactic acid, trichloroacetic acid (TCA), formalin, glutaraldehyde, cantharidin, podophyllin, Retin-A, and bleomycin. These treatments should be supervised by a health care provider.

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