Benign cutaneous infections caused by human papillomavirus (HPV) are one of the most quotidian and troublesome conditions seen in dermatological practice. This virus can cause a myriad of infectious lesions, and among them, cutaneous warts are most frequently observed. They can be further divided into common warts, plantar warts, flat warts and genital warts.
In healthy individuals, approximately 20% of warts resolve spontaneously within 3 months and 60% of them within 2 years; therefore, treatment is not always necessary. Nevertheless, most patients still decide to visit a physician due to the physical appearance, discomfort or interference with everyday activities.
Genital warts pose a significant treatment challenge for physicians. First and foremost, there is a reluctance of patients to consult a physician, and secondly, they have a propensity to relapse. Considering the latter, it must be noted that no therapeutic modality has been proven effective at achieving complete remission in every patient.
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Topical treatments
Home remedies that are used in the treatment of common warts include the application of tea tree oil, garlic extract, hyperthermic therapy and duct tape method. Duct tape method involves covering the wart with duct tape, which is left in place for six days. The site should then be soaked, filed down with emery board and left uncovered overnight, which is a process that is repeated for a total of eight cycles.
Salicylic acid products are often favored by patients, as their use is convenient, cheap and without significant discomfort. Over-the-counter preparations contain less than 17% salicylic acid, whereas physician-prescribed preparations can contain as much as 70% salicylic acid. Warts should be soaked in water for 5-10 minutes before each application, and the dead skin should be debrided afterward.
Imiquimod is a Toll-like receptor 7 analog that induces the production of inflammatory cytokines and is indicated for the treatment of genital warts in adults. However, off-label use of this immunomodulator for non-genital warts has increased in the last decade. This preparation is available as a cream in 2.5%, 3.75% and 5% strengths.
Vitamin A is widely recognized as a safe and effective topical approach for flat, common and plantar warts (also known as verruca plana, verruca vulgaris and verruca plantaris, respectively). This vitamin and other retinoids regulate keratinization and may interfere with the replication of the human papillomavirus, which is tightly synchronized with the keratinization and differentiation of epithelial cells.
The keratotic material of the wart can be submitted to cryotherapy, usually using liquid nitrogen. It can be applied by a cotton-tipped applicator or cryogen, freezing the wart and a 1 to 2 mm margin for 10 to 30 seconds. The freeze should be repeated once after a thaw of 20 seconds. Certain topical chemotherapy agents such as podophyllin can be applied afterward.
Other destructive methods of wart removal are most often used for resistant, multiple lesions, or recalcitrant warts in immunosuppressed patients. Amongst them are laser therapy (usually with a pulsed dye laser or carbon dioxide laser), photodynamic therapy, and the application of acids (including bicholoracetic and trichloroacetic acid).
Systemic approaches
Oral zinc can be a useful therapeutic modality for warts, namely in children where painful physical treatment options have limited usefulness. A placebo-controlled clinical trial where oral zinc sulphate (10 mg/kg daily) was used to treat recalcitrant warts showed complete clearance was in 87% of the treatment group versus no clearance in the placebo group.
Oral immunomodulation with high-dose cimetidine (a type-2 histamine receptor antagonist) has been proposed, as it has the propensity to enhance cell-mediated immune response. Daily doses of 30 to 40 mg/kg can be divided twice a day to four times a day for as long as 12 weeks, but thus far evidence of its efficacy has been anecdotal.
In conclusion, it is of uttermost importance when choosing from the range of wart treatments to tailor the therapy according to the needs of the patient and healthcare provider. Prevention may soon become the best approach, as the development of new strain-specific HPV vaccines against venereal warts is progressing rapidly.
Further Reading