An update on topical photodynamic therapy for clinical dermatologists

Introduction: Photodynamic therapy (PDT) involves the application of a topical photosensitizer, irradiation with light, and oxygen to produce cytotoxic reactive oxygen species that selectively destroy damaged cells while leaving normal skin intact. Topical PDT is a commonly used treatment for non-melanoma skin cancers (NMSCs) due to its excellent clearance rate and cosmetic outcomes. However, PDT is emerging as an off-label treatment modality for many dermatological conditions. Methods: A literature review using MEDLINE was performed to identify randomized controlled trials conducted for currently approved and off-label clinical indications and photosensitizers for PDT between 2012 and 2018. Results: The photosensitizer indole-3 acetic acid reduces the incubation time (<30 min), avoids the need for photoprotection after irradiation, and inflicts minimal pain. Cyclic PDT in individuals with evidence of field cancerization delays the mean time of actinic keratosis (AK) appearance and reduces the total number of new actinic keratoses. Substantial evidence exists outlining the utility of PDT in photorejuvenation due to its ability to improve skin texture, wrinkles, and firmness. The addition of microdermabrasion, microneedling, curettage, or various lasers improves clinical efficacy and cosmetic outcomes. Discussion: PDT applications are expanding rapidly. Clinicians must stay up to date regarding the efficacy and safety of PDT applications.