|Classification and external resources|
A plantar wart. Striae (fingerprints) go around the lesion.
A plantar wart (also known as "Verruca plantaris":405 and myrmecia) is a wart caused by the human papillomavirus (HPV) occurring on the sole (Latin planta) or toes of the foot. (HPV infections in other locations are not plantar; see human papillomavirus.) Plantar warts are usually self-limiting, but treatment is generally recommended to lessen symptoms (which may include pain), decrease duration, and reduce transmission.
Plantar warts are almost unknown in habitually barefoot cultures and people. This is because walking barefoot for extended periods of time strengthens the skin and keeps it dry and uncompromised as well as wearing off the virus through friction on the soles of the feet, preventing infection. While infection occurs in an estimated 7–10% of the US population; plantar warts tend to affect only 0.29% of people who have never worn shoes.
Plantar warts are benign epithelial tumors generally caused by infection by human papilloma virus types 1, 2, 4, 60, or 63, but have also been caused by types 57, 65, 66, and 156. These types are classified as clinical (visible symptoms). The virus attacks compromised skin through direct contact, entering through possibly tiny cuts and abrasions in the stratum corneum (outermost layer of skin). After infection, warts may not become visible for several weeks or months. Because of pressure on the sole of the foot or finger, the wart is pushed inward and a layer of hard skin may form over the wart. A plantar wart can be painful if left untreated.
A plantar wart is a small lesion that appears on the sole of the foot and typically resembles a cauliflower, with tiny black petechiae (tiny hemorrhages under the skin) in the center. Pinpoint bleeding may occur when these are scratched, and they may be painful when standing or walking.
Plantar warts are often similar to calluses or corns, but can be differentiated by close observation of skin striations. Feet are covered in skin striae, which are akin to fingerprints on the feet. Skin striae go around plantar warts; if the lesion is not a plantar wart, the cells' DNA is not altered and the striations continue across the top layer of the skin. Plantar warts tend to be painful on application of pressure from either side of the lesion rather than direct pressure, unlike calluses (which tend to be painful on direct pressure instead).
The best but least-used preventative appears to be to go barefoot as much as possible, thus developing thick protective skin on the soles of the feet as well as exposing them to friction (through walking) which wears off or kills the virus. Because plantar warts are incubated by shoes and spread by contact with moist walking surfaces, they can be prevented by remaining barefoot after walking in public areas such as showers or communal changing rooms until the feet have had time to dry and wear off the virus, or by wearing flip flops or sandals, not sharing shoes and socks, and avoiding direct contact with warts on other parts of the body or on other people. Humans build immunity with age, so infection is less common among adults than children.
As all warts are contagious, precautions should be taken to avoid spreading them. The British National Health Service recommends that children with warts:
- cover them with an adhesive bandage while swimming
- wear flip-flops when using communal showers
- should not share towels.
Plantar warts are not prevented by inoculation with currently available HPV vaccines, because the warts are caused by different strains of the human papillomavirus. Gardasil protects against strains 6, 11, 16, and 18; and Cervarix protects against 16 and 18; whereas plantar warts are caused by strains 1, 2, 4, and 63.
Conventional treatments that have been found to be effective include:
|First-line therapy||Over the counter salicylic acid|
|Second-line therapy||Cryosurgery, intralesional immunotherapy, or pulsed dye laser therapy|
|Third-line therapy||Bleomycin, surgical excision|
Salicylic acid - The treatment of warts by keratolysis involves the peeling away of dead surface skin cells with Keratolytic chemicals such as salicylic acid or trichloroacetic acid. These are available in over-the-counter products or, in higher concentrations, may need to be prescribed by a physician. A 12 week daily treatment with salicylic acid has been shown to lead to a complete clearance of warts in 10-15% of the cases.
Cantharadin (blister beetle extract) applied to a wart by a doctor causes a blister after 4–6 hours. One formulation is known as Cantharone (0.7% Cantharidin); a more powerful one is Cantharone PLUS which contains the same active ingredient as Cantharone, but it also contains Podophyllin (5%) and Salacylic Acid (30%).
Immunotherapy - Intralesional injection of antigens (mumps, candida or trichophytin antigens USP) is a new wart treatment which may trigger a host immune response to the wart virus, resulting in wart resolution. It is now recommended as a second-line therapy.
Liquid nitrogen - This, and similar cryosurgery methods, are a common surgical treatment which act by freezing the internal cell structure of the warts, destroying the live tissue. Up to three sessions may be required.
Electrodesiccation and surgical excision may produce scarring.
Cauterization - This may be effective as a prolonged treatment. As a short-term treatment, cauterization of the base with anaesthetic can be effective, but this method risks scars or keloids. Subsequent surgical removal is unnecessary, and risks keloids and recurrence in the operative scar.
Duct tape 
Relative effectiveness 
A 2006 review of the effects of different local treatments for cutaneous, non-genital warts in healthy people concluded: 
- overall there is a lack of evidence (many trials were excluded because of poor methodology and reporting).
- the average cure rate using a placebo was 27% after an average period of 15 weeks.
- the best treatments are those containing salicylic acid. They are clearly better than placebo.
- there is little clinical trial data for the absolute efficacy of cryotherapy
- two trials comparing salicylic acid and cryotherapy showed no significant difference in efficacy.
- one trial comparing cryotherapy and duct tape occlusion therapy showed no significant difference in efficacy.
- evidence for the efficacy of the remaining treatments was limited.
See also 
- James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.
- Warts, Plantar at eMedicine
- Howell, Phd, Dr Daniel (2010). The Barefoot Book. Hunter House.
- Amuel B. Shulman, Pod.D (1949). "Survey in China and India of Feet That Have Never Worn Shoes". The Journal of the National Association of Chiropodists. Retrieved 27 September 2012.
- Human Papillomavirus at eMedicine
- Egawa, Kitasato, Honda, Kawai, Mizushima, Ono (March 1998). "Human papillomavirus 57 identified in a plantar epidermoid cyst". British J Dermatology 138 (3): 510–14. doi:10.1046/j.1365-2133.1998.02135.x.
- "Human Papillomaviruses Compendium". Los Alamos National Laboratory. Retrieved 2013-02-05.
- Mark Davis, Bobbie Gostout, Renee McGovern, David Persing, Ronald Schut, Mark Pittelkow (August 2000). "Large plantar wart caused by human papillomavirus-66 and resolution by topical cidofovir therapy". J Am Acad Dermatol 43 (2): 340–3. doi:10.1067/mjd.2000.100534.
- Diego Chouhy, Elisa M. Bolatti, Gustavo Piccirilli, Adriana Sánchez, Ramón Fernandez Bussy, Adriana A. Giri1 (2013). "Identification of HPV-156, the prototype of a new human gammapapillomavirus species, by a generic and highly sensitive PCR strategy for long DNA fragments". Journal of General Virology. doi:10.1099/vir.0.048157-0. PMID 23136368.
- "Understanding Plantar Warts". Health Plan of New York. Retrieved 2007-12-07.
- "Clinical Knowledge Summaries: Previous version – Warts (including verrucas)" (PDF). National Health Service. January 2007. p. 2. Retrieved 2010-12-05.
- Bacelieri R, Johnson SM (August 2005). "Cutaneous warts: an evidence-based approach to therapy". Am Fam Physician 72 (4): 647–52. PMID 16127954.
- Cockayne, S.; Curran, M.; Denby, G.; Hashmi, F.; Hewitt, C.; Hicks, K.; Jayakody, S.; Kang'Ombe, A. et al. (2011). "EVerT: Cryotherapy versus salicylic acid for the treatment of verrucae--a randomised controlled trial". Health technology assessment (Winchester, England) 15 (32): 1–170. doi:10.3310/hta15320. PMID 21899812.
- Bacelieri, R.; Johnson, S. M. (2005). "Cutaneous warts: An evidence-based approach to therapy". American family physician 72 (4): 647–652. PMID 16127954.
- "Laser Surgery for Warts", webmd.com
- Kunnamo, Ilkka (2005). Evidence-based Medicine Guidelines. John Wiley and Sons. p. 422. ISBN 978-0-470-01184-3.
- Wenner, R; Askari, SK, Cham, PM, Kedrowski, DA, Liu, A, Warshaw, EM (2007 Mar). "Duct tape for the treatment of common warts in adults: a double-blind randomized controlled trial". Archives of dermatology 143 (3): 309–13. doi:10.1001/archderm.143.3.309. PMID 17372095.
- Ringold, S; Mendoza, JA, Tarini, BA, Sox, C (2002 Oct). "Is duct tape occlusion therapy as effective as cryotherapy for the treatment of the common wart?". Archives of pediatrics & adolescent medicine 156 (10): 975–7. PMID 12361441.
- Stubbings, A; Wacogne, I (2011 Sep). "Question 3. What is the efficacy of duct tape as a treatment for verruca vulgaris?". Archives of Disease in Childhood 96 (9): 897–9. doi:10.1136/archdischild-2011-300533. PMID 21836182.
- Gibbs S, Harvey I, Sterling JC, Stark R (2006). "Local treatments for cutaneous warts". In Gibbs, Sam. Cochrane Database Syst Rev 3 (2): CD001781. doi:10.1002/14651858.CD001781.pub2. PMID 16855978.