Main Issue November 2011

Laser Update: Light-Based Treatments For Recalcitrant Warts

Although not a first-line treatment, lasers can be particularly beneficial in more difficult cases of warts.

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A Q&A With E. Victor Ross, MD

What kind of difficulties do warts pose for treatment?

Warts are typically very challenging to treat, according to Dr. Ross. They are caused by the human papilloma virus, of which there are many subtypes. “Warts are easily transmissible from one person to another. People are constantly exposed to the wart virus,” says Dr. Ross. Some people never develop a wart despite multiple exposures, notes Dr. Ross. A main challenge for treatment is the persistence of the virus and even persistence of the wart despite multiple treatment attempts.

When should a clinician begin to think about lasers as a treatment possibility for warts?

According to Dr. Ross, a clinician should consider lasers when other reasonable treatment options have failed. “Typically, particularly for childhood warts, early attempts at treatment include topical home remedies such as salicylic acid and tretinoin (Retin-A Micro, Ortho Dermatologics). Topical treatments applied in the office include Cantharone as well as pyruvic acid,” he observes. Liquid nitrogen is the mainstay for office based treatment of warts, according to Dr. Ross. “It is easily accessible and typically a little painful, however, the pain is less than with other invasive remedies,” he notes. “If liquid nitrogen fails and the warts persist and are either very conspicuous or are interfering with function, lasers become a reasonable option,” according to Dr. Ross.

Dr. Ross, indicated that the main type of laser typically used for treatment of warts in children is the pulsed dye laser. “The pulsed dye laser emits yellow light and selectively heats small capillaries in the wart. Additionally there is direct heating of some of the melanin in the wart at the basal cell layer. We have done biopsies to support a role for both of these heat modalities in wart improvement,” says Dr. Ross.

The pulsed dye laser is typically deployed without any type of cooling although a small amount can be used to decrease discomfort, observes Dr. Ross. “We also occasionally use the cold air machine intermittently when the patient is having difficulty with pain,” says Dr. Ross. “Topical numbing remedies can be applied one to two hours prior to treatment of the wart with a pulsed dye laser. Typically we apply treatment with stacked pulses with the 5mm spot at relatively high fluences as much as 10-12 J/cm2 and a 1.5ms pulse duration. Generally we apply a sufficient number of pulses so that the wart becomes slightly purpuric. The warts are pared down prior to therapy with a 15 blade,” he explains.

How do you treat warts in difficult areas?

“If the wart is on the back of the hand or any area that is cosmetically conspicuous where any type of long-term sequelae would be important as far as cosmesis, sometimes only one pulse is delivered to minimize damage to the epidermis surrounding the wart and decrease the likelihood of any scarring,” notes Dr. Ross. “The concession one makes with this approach is a possible increase in the number of treatment sessions.”

Dr. Ross continues, “We apply the pulsed dye laser every three or four weeks for as many sessions as it requires to successfully destroy the wart,” says Dr. Ross. “When the patient returns, typically there is a small black eschar that we pare down just prior to the subsequent treatment.” Most warts in the pediatric population are treated on the hands and feet, simply because these are areas where there is typically access or exposure, according to Dr. Ross.

Can any other lasers be used for warts?

“The other type of laser therapy that can be applied for warts is the carbon dioxide laser,” says Dr. Ross. “We typically reserve this for very exophytic warts or when the warts are interfering with function in a significant way, for example a child that cannot hold a pencil correctly at school.” However, although the carbon dioxide laser is effective, it requires injectable anesthesia. “Most children can be talked into the injectable anesthetic, particularly since once the anesthesia takes hold, there is no continued pain; This is not the case, for example, with either the pulsed dye laser or even liquid nitrogen,” Dr. Ross observes. “Also, often we will at the same time as laser treatment, inject small aliquots of Candida antigen just adjacent to the wart. An additional step is the possible oral administration of cimetidine.”

Pulsed Dye Laser for Treatment of Pediatric Warts

  • Proposed Action
    • Selectively heats small capillaries in the wart
    • Direct heating of melanin in the wart at the basal cell layer
  • Anesthesia?
    • Typically deployed without cooling
    • Cooling or cold air permissible
    • Topical numbing permissible
  • Specifications
    • Stacked pulses; 5mm spot; 10-12J/cm2; 1.5ms pulse duration until the wart becomes slightly purpuric. Pare warts prior to therapy with a 15 blade
  • Repeat Treatments
    • Every three or four weeks for as many sessions as required to destroy the wart. If any eschar, pare down prior to treatment

E. Victor Ross, MD is Director, Scripps Clinic Laser and Cosmetic Dermatology Center, Carmel Valley, CA and Past President of the American Society for Laser Medicine and Surgery (ASLMS) San Diego, CA

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