AlegsaOnline.com

Wart (skin growth caused by human papillomavirus)

A wart is a benign skin growth caused by human papillomavirus (HPV). This article explains appearance, types, causes, transmission, diagnosis, treatments, prevention and notable distinctions.

Author: Leandro Alegsa Creation date: November 13, 2022 Last updated: April 27, 2026

simple.wikipedia.org · CC BY-SA 3.0

Overview

A wart is a small, usually benign growth of the skin that arises when certain types of human papillomavirus (HPV) infect epidermal cells. Warts vary in size, shape and location: some are rough and raised while others are flat or threadlike. Most warts are not dangerous, but they can be painful, cosmetically bothersome, or difficult to treat when they recur. For general information, see further reading on warts.

Appearance and common types

Warts often have a textured surface and may contain small, dark punctate dots that are capillaries. They are classified by appearance and location rather than by a single virus type. Common categories include:

Common warts (often on hands and fingers) — rough, raised lesions.
Plantar warts (on the soles of the feet) — may be flat from pressure and painful with walking.
Flat warts — small, smooth, slightly raised and often numerous, especially on the face or legs.
Filiform warts — elongated, threadlike projections that appear on the face or neck.
Genital warts — occur on the genital or anal area and are caused by certain HPV types distinct from typical skin warts.

Additional visual guidance is available at appearance and types.

Causes and transmission

Warts are caused by infection of epidermal keratinocytes by HPV. Different HPV types preferentially infect different skin or mucosal sites. The virus stimulates local thickening of the skin and excess production of keratin. Transmission typically occurs through direct skin-to-skin contact or indirectly via contaminated surfaces (fomites). Minor breaks in the skin, moist environments (for example, communal showers) and frequent contact with an infected area increase the chance of spread. Autoinoculation, the transfer of virus from one part of the body to another, is common. For details on viral behavior and spread see virus and transmission.

Diagnosis and natural history

Diagnosis is usually clinical, based on appearance and location. A clinician may scrape or examine the lesion; atypical or suspicious growths can be biopsied to exclude other conditions. Many warts resolve spontaneously as the immune system mounts a response, often over months to a few years, but some persist or recur. Factors such as immune suppression can make warts more numerous and more resistant to treatment.

Treatment and prevention

Treatment is chosen according to wart type, size, number and patient preference. Options include:

Topical keratolytics (salicylic acid preparations) applied regularly to soften and remove layers of infected skin.
Cryotherapy (freezing with liquid nitrogen) to destroy wart tissue.
Procedures performed by a clinician: curettage, surgical removal, laser ablation or application of caustic agents.
Topical or intralesional immunotherapies that stimulate the immune response against the virus.
Specific treatments are used for genital warts and are managed by sexual health services.

Over-the-counter, prescription, and clinic-based approaches each have advantages and drawbacks; recurrence is possible. More on therapeutic approaches is available at treatment options. Preventive measures include avoiding direct contact with warts, using footwear in communal wet areas, and in the case of genital HPV, vaccination which lowers the risk of infection with certain HPV types; see prevention and vaccines.

Notable distinctions

It is important to distinguish common cutaneous warts from genital warts and from skin lesions that may require other care. Although most cutaneous warts are harmless and self-limited, some HPV types associated with the genital tract are linked to higher health risks and require specific medical attention. When in doubt about a lesion's nature or if a wart is painful, rapidly changing, bleeding frequently, or occurs in someone with a weakened immune system, medical evaluation is recommended.

Occurrence

Warts occur at any age and appear singly or in groups, usually as sharply defined, flat hemispherical or pointed outgrowths of the skin; rarely also completely flat, predominantly on the hands and feet. They are growths of the epidermis. The warts usually have a thick, horny, sometimes somewhat fissured coating of squamous epithelial cells, under which is soft, easily bleeding tissue of keratinocytes. Scratching warts can cause them to spread on the skin, as the bleeding that occurs and the infected skin cells it contains spread the viruses further along the body.

Despite their basically benign character, warts can cause considerable cosmetic disturbance, especially if they spread further on the skin, sometimes cause severe pain in certain areas and, extremely rarely, also develop malignantly (malignant).

Blood vessels as dark spots after callus ablation

Pathogen

An infection with the wart-causing human papillomaviruses or, only in the case of dell warts, with the molluscum contagiosum virus (MCV) does not generally take a serious course. There are exceptions in the case of considerably pre-damaged people, in the case of double or secondary infections (see also Infection). This shows that in the course of evolution these viruses and their reservoir host, humans, have adapted very strongly to each other.

Damage to its reservoir host is not a beneficial effect for a virus, as it is dependent on this host for its own reproduction. The symptoms nevertheless triggered in the reservoir host are side effects of the infection. Decisive for their severity is above all the state of the immune system of the affected person.

The role of the immune system

Also and especially in the case of infections with pathogens that are already adapted to humans as their reservoir host, the state of the immune system of the affected organism plays an important role. The observation that in the case of viral infections by no means all persons in contact also become ill has various causes. For example, immunity may already exist due to previous contact with this viral variant, the viral dose or virulence may be too low for an outbreak of disease, or the immune system may be able to prevent symptoms of disease despite infection (inapparent infection or silent celebration, i.e. immunisation without vaccination or disease). If the immune system is intact and the pathogen dose is low, warts may either not develop at all, take a less severe course or regress on their own after a few months without any treatment.

Since children's immune defenses are not yet as mature, they are also more frequently affected by warts. In the first four years of life, children statistically contract up to five bacterial or viral respiratory diseases. In this phase, there is also a higher risk of infection with the human papilloma virus type 1. However, in the case of painful warts in children, they should be treated particularly quickly so that the children do not adopt an evasive posture and cause a permanent malposition of the body due to the crooked appearance.

People with a weakened immune system, such as after a serious illness or in the case of immunosuppression, are also particularly at risk, and smokers also have an increased susceptibility to warts.

In the case of a severe disease of the immune system such as a rare idiopathic CD4 lymphopenia, it is possible for warts to spread all over the body (epidermodysplasia verruciformis). The case of the Indonesian fisherman Dede Koswara (the "tree man") has been reported in the media. After a subsequently diagnosed HPV-2 infection, in addition to more or less large warts on the entire body, increasingly horny structures proliferated over a period of years, especially on the hands and feet, which looked like tree bark.

Questions and Answers

Q: What are warts?

A: Warts are growths on the skin that often resemble solid blisters and can cause pain when pressure is applied.

Q: What causes warts?

A: Warts are caused by viruses in the HPV family. As there are many types of viruses in the HPV family, there are also many types of wart.

Q: Are warts dangerous?

A: In most cases, warts are not dangerous, but they may be painful. Warts contain tissue that bleeds easily, and a bleeding of this tissue allows the wart to spread to other places.

Q: How does the virus that causes warts spread?

A: The virus that causes warts infects skin cells, and if these skin cells move to other areas, new warts can grow there. In general, coming in contact with infected tissue spreads the infection.

Q: What are some ways to get rid of a wart?

A: There are different ways of getting rid of a wart. Some options include freezing the wart with liquid nitrogen, applying salicylic acid to the wart, or having a doctor remove the wart surgically.

Q: Can warts appear in different places on the body?

A: Yes, warts can appear in different places on the body depending on the type of virus that caused them. Some common places for warts include the feet, hands, and genitals.

Q: What should you do if you have a wart?

A: If you have a wart, you may want to consult a doctor or dermatologist to discuss treatment options. You should also avoid touching the wart or letting it come into contact with other people or objects to prevent the spread of infection.

Author

AlegsaOnline.com - Wart - Leandro Alegsa

Creation date: November 13, 2022
Last updated: April 27, 2026

URL: https://en.alegsaonline.com/art/106637