Plantar wart

A plantar wart (also verruca plantaris or verruca) is a wart caused by the human papilloma virus (HPV). It is a small lesion that appears on the sole of the foot (hence the name, from Latin planta pedis, the sole of the foot) and typically resembles a cauliflower. A plantar wart may have small black specks within it that ooze blood when the surface is cut or shaved; these are abnormal capillaries. Though the name plantar wart describes specifically HPV infection on the sole of the foot, infection by the virus is possible anywhere on the body and common especially on the palm of the hand, where the appearance of the wart is often exactly as described above for plantar warts.

Additional recommended knowledge

Essential Laboratory Skills Guide

Daily Sensitivity Test

Weighing the right way

Infection and development

Human papilloma virus can be found on walking surfaces such as showers, swimming pools, or shoes. It is spread through contact, with the virus invading the skin through possibly tiny cuts and abrasions. After infection, warts may not become visible for several weeks or months. Because of pressure on the sole of the foot, the wart is pushed inward and a layer of hard skin may form over the wart. A plantar wart might be painful.^[1]

Warts may spread, develop into clusters or fuse to become a mosaic wart.

Diagnosis

  Common symptoms of plantar warts include tiny black dots on the surface, pinpoint bleeding when they are scratched, and pain in the soles of the feet when standing or walking.^[1]

Plantar warts are often similar to helomata or corns, but can be differentiated by close observation of skin striations. Feet are covered in skin striae, which are more commonly called fingerprints. 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 helomata (which tend to be painful on direct pressure instead).

Prevention

• Avoid walking barefoot in public areas such as showers, communal changing rooms. (Covering with an adhesive bandage is not a safe method as it will not last for long at all, especially while showering or swimming)
• Change shoes and socks daily.
• Avoid sharing shoes and socks.
• Avoid direct contact with warts on other parts of body or on other people.

Treatment

Humans build immunity with age, so that infection is less common amongst adults than children.^[1]

No treatment in common use is 100% effective. The most comprehensive medical review^[2] found that no treatment method was more than 73% effective and using a placebo had a 27% average success rate. The American Family Physician recommends:^[3]

Podiatrists and dermatologists are considered specialists in the treatment of plantar warts, though most warts are treated by primary care physicians.

Vaccination

Although immunization is available for the HPV and strains causing cervical cancer and venereal warts, there is currently no vaccination treatment for plantar warts.

Pharmacologic Rx

Keratolytic Chemicals

The treatment of warts by keratolysis involves the peeling away of dead surface skin cells with trichloroacetic acid or salicylic acid.

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. Distant, non-injected warts may also disappear.

Chemotherapy

Topical application of dilute glutaraldehyde (a virucidal chemical, used for cold sterilization of surgical instruments) is an older effective wart treatment. More modern chemotherapy agents, like 5-fluoro-uracil, are also effective topically or injected intralesionally. Retinoids, systemically (eg. isotretinoin) or topically (tretinoin cream) may be effective.

As warts are contagious, precautions should be taken to avoid spreading.

Surgical

• Liquid nitrogen : Cryosurgery with liquid nitrogen. A common treatment that works by producing a blister under the wart. It is painful but usually nonscarring.
• Electrodesiccation and surgical excision produce scarring. If the wart recurs, the patient has a permanent scar along with the wart.
• Lasers may be effective, especially the 585nm pulsed dye laser which the most effective treatment of all, and does not leave scars, but is generally a last resort treatment as it is expensive and painful, and multiple laser treatments are required (generally 4-6 treatments repeated once a month until the wart disappears).

Other

• X-ray is an old method that is seldom recommended due to the long term adverse side effects of irradiation.

• Duct tape occlusion therapy: The wart is kept covered with duct tape for six days, then soaked and debrided with a pumice stone. The process is repeated for 6 to 8 weeks.^[4]
• Watchful waiting may be appropriate since many warts will eventually resolve due to the patient's own immune system. In many cases, the body will become naturally immune to the wart and verrucæ will turn black and effectively fall off, although it can be two years or longer before this takes place.

Relative effectiveness of treatments

A 2006 study assessed the effects of different local treatments for cutaneous, non-genital warts in healthy people.^[2] The study reviewed 60 randomized clinical trials dating up to March 2005. The main findings were:

• 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 surprisingly little evidence for the absolute efficacy of cryotherapy.
• two trials comparing salicylic acid and cryotherapy showed no significant difference in efficacy.
• one trial comparing salicylic acid and duct tape occlusion therapy showed no significant difference in efficacy.
• evidence for the efficacy of the remaining treatments was limited.

References