Actinic keratosis (AK) is a precancerous lesion that occurs in areas that are chronically exposed to sunlight and has the potential to develop into invasive cutaneous squamous cell carcinoma (cSCC). We investigated the efficacy of 20% 5-aminolevulinic acid-photodynamic therapy (ALA-PDT) with LED red light for the treatment of AK in Chinese patients by examining changes in dermoscopic features, histopathology and fluorescence after treatment.

Twenty-eight patients with fourty-six AK lesions from March 2022 to September 2023 were treated with 20% ALA, and 3 hours later, they were irradiated with LED red light (80-100 mW/cm2) for 20 minutes. A session of 20% ALA-PDT was performed once a week for three consecutive weeks, and the dermoscopic, histopathological, fluorescent and photoaging outcomes were measured one week after the treatment.

One week after ALA-PDT, complete remission (CR) was reached in 53.6% of patients. The CR of Grade I AK lesions was 100%, that of Grade II lesions was 71.4%, and that of Grade III lesions was 38.1%. There was a significant improvement in the dermoscopic features, epidermal thickness and fluorescence of the AK lesions. The presence of red fluorescence decreased, and there was an association between CR and post-PDT fluorescence intensity. ALA-PDT also exhibited efficacy in treating photoaging, including fine lines, sallowness, mottled pigmentation, erythema, and telangiectasias, and improved the global score for photoaging. There were no serious adverse effects during or after ALA-PDT, and 82.1% of the patients were satisfied with the treatment.

AK lesions can be safely and effectively treated with 20% ALA-PDT with LED red light, which also alleviates photoaging in Chinese patients, including those with multiple AKs. This study highlights the possibility that fluorescence could be used to diagnose AK with peripheral field cancerization and evaluate the efficacy of ALA-PDT.