What are warts?
Common warts, also known as verruca vulgaris, are among the most common problems managed by dermatologists and family practice physicians. Although not life-threatening, warts are often a source of a low self-esteem and embarrassment.

Common warts are caused by the human papilloma virus (HPV). The virus replicates inside the cells of the top layer of the skin. HPV “hijacks” the skin cells and tells them to divide. Rapidly dividing cells form protruding growths on the skin. These growths are not cancerous.

The HPV virus is transmitted from person to person, usually by skin to skin contact. The risk of catching common warts from another person is small. Warts are more common where skin has been broken, for example where fingernails are bitten.

How many kinds of warts are there?
The most common types of warts are common warts (verruca vulgaris), foot warts (verruca plantaris), and flat warts (verruca plana). The type of wart you get depends on a kind (or serotype) of HPV that caused it. There are more than 100 subtypes of HPV virus, and they all cause different types of warts. New types of HPV are discovered every year. All of the subtypes of HPV virus are similar to each other and share about 90% similarity in structure. The differences in structure of different HPV types produce differences in types of warts that can occur.

In addition to common warts, HPV is implicated in multiple diseases of the skin and mucous membranes, such as epidermodysplasia verruciformis, condyloma accuminata (genital warts), cervical dysplasia and carcinoma, and laryngeal papillomatosis.. Various serotypes cause specific types of warts, and favor certain anatomic locations. HPV type 1 is known to cause deep warts on hands and feet, types 2,4,27,29 are the culprits in common warts, types 3,10,28,49 cause flat warts, types 5,8,9,12,14 cause epidermodysplasia verruciformis. Most of the warts are harmless and never turn into cancer.

Currently there is no antiviral therapy available to eradicate the wart virus. HPV is resistant to freezing, drying, and solvents. The warts will go away when patient’s own immune system suppresses the HPV virus. While you wait for this suppression to occur, your doctor may use multiple types of treatment to speed up the process of recovery.

Destructive modalities include surgical removal, cryotherapy, surgery, electrocautery, cantharidin, and topical application of salicylic acid. None of these methods is 100% effective. The majority of therapies require multiple treatment sessions. The purpose of these treatments is not to kill the HPV virus. As pointed out above, this is not possible. Destructive treatments simply destroy or remove cells in which HPV virus accumulates. These modalities reduce viral load on the body, and allow the patient’s immune system to finish the job of destroying warts.

Immunotherapy attempts to use the body’s own immune system to get rid of warts. In this method, the patient is made allergic to a certain chemical which is then applied to the wart. Redness and irritation occur around the treated warts, and may result in their disappearance. Imiquimod is a cream used to boost the immune reaction of the body and clear the warts.

Since warts differ depending on their type and location on your body, only your doctor can choose the best method to treat your warts.

Silverberg NB. Human papillomavirus infections in children. Current Opinion in Pediatrics. 16(4):402-9, 2004 Aug.

Alexander Doctoroff, D.O., F.A.O.C.D.
Assistant Chief of Dermatology,
Veterans Administration Medical Center
East Orange, New Jersey

Assistant Clinical Professor of Medicine,
University of Medicine and Dentistry of New Jersey