While many warts resolve without treatment, therapy may be required when plantar warts are painful or affect a patient’s ability to walk. Accordingly, this author discusses his clinical experience with a variety of modalities ranging from pulsed dye laser therapy and topical treatments to surgical excision.
Warts are the most common viral infection of the skin and they are most often caused by human papillomavirus (HPV) type 1. There are more than 120 different varieties of HPV and only certain varieties are the cause of warts. Certain virus types tend to infect specific anatomical areas such as the plantar surface of the foot. At least 50 percent of adults will be infected with verruca during their lifetime.1 Although the current prevalence of plantar warts in adults is unknown, plantar warts have been estimated to occur in 7 to 10 percent of adults.2
Plantar warts can occur anywhere on the bottom of the foot but tend to produce symptoms in parts of the body that experience pressure and friction.
The HPV virus infects only the superficial layer of skin and produces a thickened, callus-like growth. If this growth is located in an area subjected to pressure, it can become tender. Certainly, warts can present with much variety in size and depth, but they do not go below the basement membrane of the skin.
Characteristically, warts resolve spontaneously although one may need to treat warts that affect the patient’s ability to walk or warts that cause pain. The incubation period of verruca is unknown but may last from months to years. However, I have found that when people think they stepped on a foreign body, this can be a route of entry for the infection.
Inoculation of the skin usually occurs when one comes into contact with others infected with plantar warts. This contact may occur in areas like showers or pool areas. The mechanism of action for spontaneous resolution of the warts seems to be dependent on developing immune lymphocytes that kill the virus infected cells. It is likely that the levels of neutralizing antibodies in the blood induced by inoculation with HPV proteins can protect against related infections.
Determining Initial Treatment Options
Generally, when a patient comes into my office for treatment of verruca, I look at a few variables that bring me to my treatment protocol. These variables are as follows:
• age of the patient;
• duration of the wart;
• number of warts;
• pain tolerance of the patient; and
• presence or lack of pain with the warts.
Once I consider these factors, I explain all of the treatment options for the individual patient. I explain to the patient or parent that warts are caused by the HPV virus. (As I am sure you are aware, not too many patients understand this unless they search it on the Internet.) I then explain that it takes weeks or even months to eradicate warts. Of course, if the patient opts for surgical excision by cold steel or the use of a CO2 laser, then this would be a quicker “cure.”
Of course, as we all know, there really is no true cure. We must stress to the patients that if they get a wart, they are more likely to get more warts or have recurrence.
If the patient is a child or the lesions are not painful, I usually recommend oral and topical treatment in concert. I offer cimetidine (Tagamet, GlaxoSmithKline) or vitamin A plus zinc in a combined tablet along with any of the topical drying agents available on the market. The dosage of cimetidine is 30 to 40 mg/kg a day. It is very important to stress to the patient the importance of being adherent with treatment and keeping the treated area as dry as possible.
The next non-surgical option I offer is chemotherapy utilizing acid under occlusion. I like to use 80 to 90% monochloroacetic acid. This is what Harvey Lemont, DPM, uses to this day and I certainly think his opinion is of value.3 I see the patient in the office once every 10 to 14 days, apply the acid to the wart(s) and cover the warts with moleskin. Patients leave this in place for three to four days and stay in a dry environment. This includes putting a bag over the foot in the shower.
I then advise patients to apply a topical salicylic acid patch until the next visit. When they return, I debride the tissue, apply the acid cover and repeat the aforementioned steps. This protocol continues until there is resolution of the warts or until the patient chooses to try another treatment.
Another method of treatment is the use of Candida injected just below one lesion. This is much like using bleomycin (Blenoxane, Bristol-Myers Squibb) in order to create an antigen response, which essentially tricks the body into fighting the HPV after recognizing Candida as the enemy. Since you are creating an immune response, it is not necessary to inject more than one lesion.
There are other viable treatments you may wish to employ. These include the use of bleomycin, imiquimod (Aldara, 3M), cantharidin (Canthacur, Paladin Laboratories) and others. I personally have not had success with any of these treatments but they certainly are options to consider.
I think it is always best to use combination therapy whenever possible. This is why I will have the patient utilize cimetidine as well as some type of formaldehyde drying agent in conjunction with other treatments between visits. Adherence is always an issue especially if you are in a warmer climate where people like to swim. I encourage the patient to keep the foot completely dry if possible. This even includes putting a bag over the foot when showering or bathing as I mentioned previously. Any moisture is going to affect treatment negatively.
A Closer Look At Pulsed Dye Laser Treatment
My mainstay of treatment is pulsed dye laser treatment. I would recommend buying a used laser unless you will also use the laser for onychomycosis and/or spider veins. I find pulsed laser treatment to be at least as effective as any other non-surgical treatment.
I treat the patient every two weeks until I can see a return of normal skin lines. In my experience, pulsed dye laser treatment typically requires five to six treatments, depending on how thick the skin is in the area being treated as well as how long the wart(s) have been present. The plantar heel area can take up to 10 treatments or more. In between treatments, I have the patients use a topical drying agent and also use oral medication if they are amenable.
The pulsed dye laser treatments are somewhat painful but brief. They also do not require any post-treatment care. The more power you can use, the quicker the resolution but you have to weigh this with patient tolerance to the treatment. You must debride the lased wart tissue before each laser treatment. Typical settings are 12 to 14 J/cm2. You may also have patients use an OTC acid topical between visits if they are willing to be adherent. If the aforementioned non-surgical treatment fails, I will then utilize cold steel or a CO2 laser. This is mostly dependent on what kind of wart I am trying to treat.
What You Should Know About Using The CO2 Laser
There are several pearls on using the CO2 laser for treatment of warts. Make sure you ablate 3 mm beyond the visual border of the lesion, just like you would do with cold steel debridement. Use a skin marker to demarcate the lesion plus the 3 mm beyond the border. The typical setting that I use is 3W of continuous power. I also like to utilize loupes when I do the procedure as you can really discern the skin lines.
I first circumscribe the entire lesion. If there is a small lesion just outside the main lesion, I include that in the demarcation instead of creating a little skin island. I then use a scribble technique back and forth in a pattern from top to bottom or side to side depending on the area. Between passes of the laser, I use a 4 mm curette to remove the lased tissue. I also use a sterile wet sponge for atraumatic debridement of the area before using the curette to debride the tissue. This makes it easier to remove the ablated tissue. I also send some of this tissue to the pathologist.
I continue this scribble and curette technique until I see only white basement membrane. Then I defocus the laser by pulling it back and cauterizing the area. Be careful here as you can easily penetrate the basement membrane and create holes that could cause unwanted scarring. Once you are finished, cover the surgical site with silver sulfadiazine, a non-adherent dressing and a sterile bandage. Have the patient change the dressing once a day. Healing takes about a month.
When Patients Do Not Respond To Conservative Methods
If lesion(s) appear to be well encapsulated and are not likely to respond to lasers due to thickness, I am more inclined to go straight to surgical treatment. I might even use the pulsed dye laser in the early healing period after surgical removal if I can see any signs of recurrence.
If the patient has failed all of the aforementioned approaches or there are too many warts to treat, I will employ the Panacos graft technique. This procedure involves taking a small piece of wart and implanting it into the foot (usually the opposite foot) in the subcutaneous layer. This will hopefully initiate the body’s own immune system to recognize this “foreign” body and mount an immune response to the viral infection. I have found this has a very high success rate. The typical time between the procedure and resolution of all warts is approximately four months. Accordingly, it is important to explain to the patient that it will take some time to see any results.
Step-By-Step Insights On The Excisional Biopsy
Surgical excisional biopsy is a very effective (about 85 percent in my experience) procedure and also confirms that it is in fact a wart. It is important to obtain patient consent for this procedure, preferably a signed consent form. At the very least, one should document a verbal consent. This is just good practice and can save you any problems should any complication arise from this simple procedure.
If necessary, you can prescribe an anti-anxiety medication such as lorazepam (Ativan) preoperatively. If appropriate, a local anesthetic block with epinephrine is ideal as long as it is not for a toe. I utilize a V block with a 27-gauge needle. Ensure standard sterile prep to the surgical area.
Circumscribe the lesion using a skin scribe and create a 3 mm border. Then excise the lesion down to the basement membrane. I use a combination of a 15 blade and a dermal curette. Be careful not to enter the subcutaneous layer as this can cause scarring.
I like to cauterize the area with 80% monochloroacetic acid with just two to three seconds of application. Send the specimen off to the lab. Depending on the size of the lesion, you can dress this with a topical antibiotic of choice and small sterile bandage. Have the patient provide local wound care and follow up as you see fit. If I see any sign of recurrence during the recovery period, I will often use the pulsed dye laser, which can stave off any recurrence.
I am sure many people reading this likely manage their verruca in a different manner. However, just as I prefer to perform a Scarf procedure for my bunionectomies, there is more than one way to skin a fish. I hope I was able to provide you with some pearls about how to treat warts effectively while keeping practice management in mind.
Dr. Bregman is the President of the Association of Extremity Nerve Surgeons. He is a Fellow of the American College of Foot and Ankle Surgeons, and a Fellow of the American Society of Podiatric Surgeons. He is in private practice at Barrett Foot and Ankle Center in Las Vegas.
1. Androphy AJ, Lowly DR. Warts. In Wolff K, et al. (eds.): Fitzpatrick’s Dermatology in General Medicine. McGraw-Hill Medical, New York, 7th ed., vol. 2, pp. 1914-1923, 2008.
2. Silverberg NB. Human papillomavirus infections in children. Curr Opin Pediatr. 2004;16(4):402-9.
3. Personal communication with Harvey Lemont, DPM.
For further reading, see “Current Concepts In Managing Plantar Warts” in the December 2010 issue of Podiatry Today.