Warts are contagious viral skin tumours. They are usually benign. In persons with impaired immunity, warts may become malignant. Warts are a very common dermatological complaint, affecting 75% of people during their lives.
Warts are contagious and may be transmitted via contact. You can reinfect yourself by shaving around infected areas. They may appear at any age, but are more common in children and young adults, whose immune systems may not be fully developed.
The human papilloma virus (HPV) family, of which more than 80 types are known, causes this skin infection. Some types may cause the common wart, which can appear on the skin of the hands, feet and nail beds.
Other types are found around the genitals (genital warts). They can also cause papillomas on the vocal cords. Some HPV subtypes are involved in the development of malignancy.
Different types of warts are recognised.
Common warts (verrucae vulgaris) – sharply demarcated, rough-surfaced, round or irregular, firm, light grey, yellow, brown or greyish-black tumours that measure 2 mm to 10 mm in diameter. They appear most often on sites subject to trauma (e.g. fingers, elbows, knees, face and scalp), but may spread elsewhere.
Digitate warts – horny and fingerlike, with pea-shaped bases; they appear on the scalp or near the hairline.
Periungual warts – around the finger nails. They can also occur in clusters. They are rough, irregular and elevated, and may extend under the nails, causing pain.
Filiform warts – long, narrow, small growths usually seen on the eyelids, face, neck or lips.
Flat warts – slightly raised, smooth, flat, yellow-brown lesions that occur more commonly in children and young adults, most often on the face (also on neck, chest, knees, hands, wrists or forearms) and along scratch marks through self-infection. They appear in groups of up to several hundred.
Warts with unusual shapes – most frequent on the head and neck, especially on the scalp and bearded region.
Genital warts – these can affect both men and women.
Plantar warts – warts, sometimes painful, on the soles of the feet.
Most people get warts, but they are more common in children and young adults.
Warts, if left untreated, will develop in various ways. Most common warts will grow slowly. Eventually growth reverses spontaneously and the warts disappear within two years. If they are treated, they will disappear sooner. Some warts can be quite persistent and usually continue to grow, and even undergo malignant change, depending on the type of HPV involved.
It is said that, in children, 80% lose their warts spontaneously in nine months.
Young people are most at risk; as one gets older, the immune system becomes better prepared for the viruses. Skin trauma can worsen infection and cause spreading through self-infection (auto-inoculation). The viruses are spread by direct contact, so avoiding physical contact with other people’s warts may be a good idea.
When to see a doctor
When warts increase in number and size and cause embarrassment, it is advisable to have them treated. Although most warts do not cause serious harm, early treatment may prevent therapy-related disfigurement. When non-prescription remedies don’t work, it is also wise to seek further help.
Skin cancer is a possibility that must always be kept in mind. When a lesion changes in colour or size, especially in older people, a medical practitioner should assess it. Malignancy arising in a common wart is extremely uncommon. When your child has warts, you should visit the doctor with him or her to provide an accurate history. Know which treatments have been tried already. Ideally the person should be seen by the same doctor for follow-up, or at least by someone from the same practice. Continuity of care can help speed up recovery by avoiding repetition.
The doctor will obtain a history and do an examination. In most cases there won’t be any need for further tests. In older people, the doctor might excise the lesion for examination by a pathologist to confirm the diagnosis and exclude more serious conditions.
Treatment depends on the duration, type and extent of the lesions, your age, your immune status and your desire for treatment. 66% of common warts disappear within two years due to the immune response, and 20% of warts disappear within six months.
Warts can initially be treated at home without your seeing a doctor. Non-prescription drugs come in liquid, gel and ointment form. Most preparations contain salicylic acid, which can soften the warts and dissolve them. This treatment doesn’t cause scarring.
The affected area should first be soaked in warm water to soften the skin so that medication can penetrate it. Dead skin can be gently rubbed off with a washcloth or pumice stone. However, don’t traumatise the wart, as this may spread the virus and cause new warts. It is a good idea to apply Vaseline gel around the affected part to prevent the agent getting onto healthy skin.
Alternatively, use zinc oxide plaster to cover the unaffected skin. Then apply the preparation onto the affected part and leave it there for as long as possible.
Podophyllin is the treatment of choice for anogenital warts. It works similar to the salicylate-based medications, but has a fairly corrosive effect on normal skin. Zinc oxide plaster can be used to protect the normal skin.
Flat warts can often be treated successfully with daily applications of tretinoin (as used in acne). If sufficient peeling does not occur for wart removal, another irritant such as benzoyl peroxide or salicylic acid cream can be applied sequentially with tretinoin.
Injection of bleomycin into the lesions has been tried, but complications may occur. Your doctor would therefore use this medication with caution. Only specialists with experience should use this method.
Cryotherapy is highly efficient, but painful. Liquid nitrogen (which is at a very low temperature) is applied with a cotton wool stick or a fine nozzle to freeze the wart and kill it. It subsequently is replaced by healthy skin and peels away. Sometimes frequent applications may be required for stubborn warts. In fact, often up to five visits, at monthly intervals, are needed. This treatment rarely leaves scars, but this also depends on the size of the wart. Hypopigmentation, following treatment is a major problem, especially in dark skin.
Warts can also be treated with laser. This can be very efficient. This treatment is very expensive.
Some lesions can be excised under local anaesthetic. This has the advantage of microscopic examination for diagnostic reasons. The major disadvantage is scarring. It should only be used as a last resort.
Sometimes warts can recur at the wound edge where a wart has been treated, requiring further treatment.
Good general hygiene and caution touching infected areas are important to prevent warts.
Reviewed by Prof H.F. Jordaan, MBChB, MMed (Derm).