A wart is a small, rough growth resembling a cauliflower or a solid blister. It typically occurs on humans’ hands or feet but often in other locations. Warts are caused by a viral infection, specifically by one of the many types of human papillomavirus (HPV). There are as many as 10 varieties of warts; the most common considered to be mostly harmless. It is possible to get warts from others; they are contagious and usually enter the body in an area of broken skin. They typically disappear after a few months but can last for years and can recur.
A range of types of wart 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 roughened surface, most common on hands, but can grow anywhere on the body;
- Flat wart(Verruca plana), a small, smooth flattened wart, flesh-colored, 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.
- Mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet;
- 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
Warts are caused by the human papilloma virus (HPV). There are about 130 known types of human papilloma viruses. HPV infects the squamous epithelium, usually of the skin or genitals, but each HPV type is typically only able to infect a few specific areas on 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 genitaldysplasia – “high-risk” HPV types are associated with cancers, notably cervical cancer, and can also cause some vulvar, vaginal, penile, and 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(myrmecia) – HPV type 1 (most common); also types 2, 3, 4, 27, 28, and 58 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.
- 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.