Warts are non-cancerous viral growths usually occurring on the hands and feet but which can also affect other locations, such as the genitals or face. One or many warts may appear. They are distinguished from cancerous tumors as they are caused by the human papillomavirus, rather than a cancer growth. Factors that increase the risk include the use of public showers and pools, working with meat, eczema, and a weak immune system. The virus is believed to infect the host through the entrance of a skin wound. A number of types exist, including plantar warts, "filiform warts", and genital warts. Genital warts are often sexually transmitted. Without treatment, most types of warts resolve in months to years. Several treatments may speed resolution, including salicylic acid applied to the skin and cryotherapy. In those who are otherwise healthy, they do not typically result in significant problems. Treatment of genital warts differs from that of other types. Infection with a virus, such as HIV, can cause warts. This is prevented through careful handling of needles or sharp objects that could infect the individual through physical trauma of the skin, plus the practice of safe sex using barrier methods such as condoms. Viruses that are not sexually transmitted, or are not transmitted in the case of a wart, can be prevented through several behaviors, such as wearing shoes outdoors and avoiding unsanitized areas without proper shoes or clothing, such as public restrooms or locker rooms. Warts are very common, with most people being infected at some point in their lives. The estimated current rate of non-genital warts among the general population is 1–13%. They are more common among young people. Before widespread adoption of the HPV vaccine, the estimated rate of genital warts in sexually active women was 12%. Warts have been described as far back as 400 BC by Hippocrates.
Types
A range of types of warts have been identified, varying in shape and site affected, as well as the type of human papillomavirus involved. These include:
Common wart (verruca vulgaris), a raised wart with a roughened surface, most common on hands, but can grow anywhere on the body. Sometimes known as a Palmer wart or junior wart. Flat wart (verruca plana), a small, smooth, flattened wart, flesh-coloured, which can occur in large numbers; most common on the face, neck, hands, wrists, and knees. Filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips. Genital wart (venereal wart, condyloma acuminatum, verruca acuminata), a wart that occurs on the genitalia. Periungual wart, a cauliflower-like cluster of warts that occurs around the nails. Plantar wart (verruca, verruca plantaris), a hard, sometimes painful lump, often with multiple black specks in the center; usually only found on pressure points on the soles of the feet and between toes. Mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet.
Causes
Warts are caused by the human papillomavirus (HPV). There are about 130 known types of human papillomaviruses. HPV infects the squamous epithelium, usually of the skin or genitals. Each HPV type is typically only able to infect a few specific areas of the body. Many HPV types can produce a benign growth, often called a "wart" or "papilloma", in the area they infect. Many of the more common HPV and wart types are listed below.
Common warts – HPV types 2 and 4 (most common); also types 1, 3, 26, 29, and 57, and others. Cancers and genital dysplasia – "high-risk" HPV types are associated with cancers, notably cervical cancer, and can also cause some vulvar, vaginal, penile, anal and some oropharyngeal cancers. "Low-risk" types are associated with warts or other conditions. High-risk: 16, 18 (cause the most cervical cancer); also 31, 33, 35, 39, 45, 52, 58, 59, and others. Plantar warts (verruca) – HPV type 1 (most common); also types 2, 4, 27, 28, and others. Anogenital warts (condylomata acuminata or venereal warts) – HPV types 6 and 11 (most common); also types 42, 44, and others. Low-risk: 6, 11 (most common); also 13, 44, 40, 43, 42, 54, 61, 72, 81, 89, and others. Verruca plana (flat warts) – HPV types 3, 10, and 28. Butcher's warts – HPV type 7. Heck's disease (focal epithelial hyperplasia) – HPV types 13 and 32.
Pathophysiology Common warts have a characteristic appearance under the microscope. They have thickening of the stratum corneum (hyperkeratosis), thickening of the stratum spinosum (acanthosis), thickening of the stratum granulosum, rete ridge elongation, and large blood vessels at the dermoepidermal junction.
Diagnosis
On dermatoscopic examination, warts will commonly have fingerlike or knoblike extensions.
Prevention Gardasil is an HPV vaccine aimed at preventing cervical cancers and genital warts. Gardasil is designed to prevent infection with HPV types 16, 18, 6, and 11. HPV types 16 and 18 currently cause about 70% of cervical cancer cases, and also cause some vulvar, vaginal, penile and anal cancers. HPV types 6 and 11 are responsible for 90% of documented cases of genital warts. Gardasil 9 protects against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58. HPV vaccines are sometimes used off-label to treat existing warts, including common and plantar warts. The efficiency of HPV vaccines as a treatment for existing warts seems to decline with age, with one study finding a cure rate of 59.6% for patients under 40 and of 25% for those 40 or older.
Disinfection The virus is relatively hardy and immune to many common disinfectants. Exposure to 90% ethanol for at least 1 minute, 2% glutaraldehyde, 30% Chlorhexidine, and/or 1% sodium hypochlorite can disinfect the pathogen. The virus is resistant to drying and heat, but killed by 100 °C (212 °F) temperature and ultraviolet radiation.
Treatment
There are many treatments and procedures associated with wart removal. A review of various skin wart treatments concluded that topical treatments containing salicylic acid were more effective than placebo. Cryotherapy appears to be as effective as salicylic acid, but there have been fewer trials.
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