Description of a plantar wart
Plantar warts occur on the sole (plantar surface) of the foot. They can be very painful because the entire weight of the body presses against them continuously when standing or walking. Plantar warts are usually rough, bumpy, and spongy, although some may be thick and scaly. Most are gray or brown and have a center with one or more dark pinpoints. These are tiny capillaries that supply blood to the wart. Scraping the wart may cause it to bleed. Untreated, plantar warts may grow up to an inch in circumference and may spread into clusters.
Cause of a plantar wart
Warts are benign tumors that can occur anywhere on the skin. The human pappiloma virus (HPV), a common organism, causes warts, therefore it is contagious. The virus is often encountered on contaminated surfaces, typically the tile floors of public locker rooms, showers, swimming pools and doctor cabinets and invades the body through tiny cuts or breaks in the skin. Normally, antibodies in the blood kill the virus. Some people are more susceptible to the human pappiloma virus than others, however, and HPV takes refuge in the skin (not the blood).
A plantar wart is similar in structure to an iceberg. The part on the surface is a small fraction of the entire anomaly. Often, the portion of the wart under the skin is at least twice as big as the part you can see.
Many of these viruses die within a year or two and the warts they produce simply disappear. Many podiatrists recommend having them removed because they are contagious, irritating and are often painful.
Treatment of a plantar wart
The over-the-counter medications have a difficult time penetrating the thick skin on the bottom of the foot, so they do not work well in this area. Professional treatment of warts may include burning with topical acids, freezing with liquid nitrogen, surgically removing them with or without the use of a laser, and more recently, the use of intra-lesional injection of Bleomycin.
All methods have the possibility of the wart coming back, especially if it is latent or in infra-clinical state (presence of viral proteins and particles not visible to the naked eye).
The most utilised method at our clinic is the intralesional injection of bleomycin with a variable concentration of 0.25 UI/ml to 1 UI/ml . The intralesional injections, are the easiest to manipulate and are more precise. The solution is injected with a syringue under pressure (no needles). When injected, there is a normal 30 to 50% loss of the product. Therefore we inject from 1 to 2 ml /wart/visit. The follow-up visit is usually 9 to 10 weeks later, where the podiatrist evaluates the lesion, and looks for signs of complete healing. Some pain may be associated with the injection, described by the patients as pinching of the skin, and a blister formation with black to red discoloration is sometimes seen for the next few weeks. Some patients complain of pain for 3 to 4 days, some complain of pain for 3 to 4 weeks. Over the counter oral anti-inflammatories (Mortin, Advil), or application of ice may be used to alleviate the pain. The general complications related to the use of the diluted bleomycin for plantar warts are the followig: urticaria, no severe complications; Local complications: Raynaud’s syndrome, local necrosis and ungual dystrophy.
Bleomycin is an excellent therapeutic alternative for resistant warts, and it has to be used by a trained practitionner. This therapy is proposed in recent journals of the American Academy of Dermatology (Guidelines of care for warts JAAD 1995), and in the guidelies of care published by the American Academy of Dermatology (Guidelines of care for nail disorders 1995).
Surgical excision of the wart has a good success rate with a relatively low rate of recurrence. It is performed under local anesthesia. There is some discomfort (since we excise the wart to the dermis level) and it takes several weeks for the area to completely heal. Normal activity can generally be resumed in a few days depending on the size and number of warts that have been removed. The risks associated with surgical removal of warts are the possibility of infection and the formation of a scar, which can be painful when weight is applied while walking.
Laser removal of the wart works by burning the wart with a laser beam. The area must be numbed with an anesthetic prior to the procedure.
The results of conventional treatments are slow. For plantar warts, cryotherapy (liquid nitrogen, Histofreeze…) associated with salicylic acid give 50% sucess rate after 12 weeks of treatment; 50% of the remaining patients need to continue the treatment for another 12 weeks to get good results. When the warts are on the bottom of the foot, this treatment can be very painful and take several days or weeks to heal.
Topical acids can be used as a single treatment by the podiatrist and can also be a useful mean of treating warts. The advantages of this treatment are that they are nearly painless (at one point we get to the dermis and it is painful) and there are almost no restrictions of activity (no application of water for 24 hours to the treated area). The disadvantages are that it requires weekly applications, may take longer.
Prescription topical and/or oral medication may be used in some cases.
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