Photodynamic therapy for warts

Photodynamic therapy (PDT) is a non-invasive, targeted treatment that harnesses the interaction between a photosensitizing agent, a specific wavelength of light, and oxygen to selectively destroy abnormal or neoplastic skin cells. (1)

The procedure involves the application of a topical photosensitizer - most often 5-aminolevulinic acid (5-ALA) or methyl aminolevulinate (MAL) - which is allowed to incubate for a defined period to ensure selective uptake by dysplastic cells. Following this, the area is exposed to a specific light source, triggering a photochemical reaction that produces reactive oxygen species and induces cell death.

PDT is particularly advantageous in treating large areas of field cancerization, including extensive actinic damage, with minimal scarring and excellent cosmetic outcomes.

Treatment-resistant viral warts have also shown notable improvement when treated with red-light PDT with 20% 5-ALA. (2) Similarly, red-light PDT with 20% 5-ALA has shown efficacy in treating condylomata acuminata, with the majority of patients achieving complete lesion clearance. (3)

Compared to other wart therapies, PDT represents a significant advancement in wart treatment, as it not only targets visible lesions but also can treat latent HPV-infected cells and helps reduce the overall viral load. (4)

A systematic review and meta-analysis of 19 randomised controlled trials found PDT resulted in low recurrence rates, minor adverse reactions, and positive clinical outcomes. (5)

References

1. Braathen LR et al. International Society for Photodynamic Therapy in Dermatology. Guidelines on the use of photodynamic therapy for nonmelanoma skin cancer: an international consensus. International Society for Photodynamic Therapy in Dermatology, 2005. J Am Acad Dermatol. 2007 Jan;56(1):125-43
2. Radakovic S, Silic K, Tanew A. Complete resolution of disseminated cutaneous warts after repetitive partial treatment with ALA PDT - indication of a PDT-induced systemic immune response. J Dtsch Dermatol Ges. 2020 May;18(5):490-492.
3. Buzzá HH et al. HPV-induced condylomata acuminata treated by Photodynamic Therapy in comparison with trichloroacetic acid: A randomized clinical trial. Photodiagnosis Photodyn Ther. 2021 Sep;35:102465.
4. Hu Z, Liu L, Zhang W, Liu H, Li J, Jiang L, Zeng K. Dynamics of HPV viral loads reflect the treatment effect of photodynamic therapy in genital warts. Photodiagnosis Photodyn Ther. 2018 Mar;21:86-90.
5. Shen S, Feng J, Song X, et al. Efficacy of photodynamic therapy for warts induced by human papilloma virus infection: A systematic review and meta-analysis. Photodiagnosis Photodyn Ther. 2022 Sep;39:102913.