Actinic keratosis is the precancerous lesion of squamous cell carcinoma. Their multiple appearance on one area reflects field cancerization. Therefore active treatment of the field is necessary to avoid the development of incidental squamous cell carcinoma. Conventional photodynamic therapy (PDT) is a widely used therapeutic method for actinic keratosis. Er:YAG (erbium:yttrium-aluminium-garnet) ablative fractional laser (AFL) - assisted PDT is used to increase the therapeutic efficacy of conventional PDT.
The aim of this study was to assess the differences between conventional PDT and Er:YAG - assisted PDT both in efficacy and rejuvenation effect.
To investigate the therapeutic efficiency, sixteen patients with actinic keratosis and chronic sun-damaged skin were irradiated with wIRA lamp on the half side of the skin involved in actinic keratosis – after 20% 5-aminolevulinic acid was applied as photosensitizer. The other side of the skin was pre-treated with Er:YAG-AFL before 5-ALA. 24/48 hours and 3 months after the treatment biopsy samples were taken to measure the degree of the keratinocyte dysplasia compared to the control (untreated) samples. P53 mutant keratinocytes were detected with immunohistochemical staining. The number and grade of actinic keratosis and the objective signs of photoaging was also assessed.
In our hands, both conventional PDT and Er:YAG-AFL - assisted PDT led to great reduction in the number of actinic keratosis, and this decrease was significantly higher in the case of Er:YAG-AFL PDT. Both improved global photoaging, but we found no significant differences between the two methods. According to the immunohistochemical staining, both decreased the number of p53 mutant keratinocytes in the epidermis. We found no significant differences in the therapeutic efficiency between Er:YAG-AFL PDT and conventional PDT regarding clinical and immunohistochemical evaluation.

Efficacy and photorejuvenation effect of conventional photodynamic therapy (PDT) and Er:YAG (erbium:yttrium-aluminium-garnet) ablative fractional laser – assisted PDT in multiple actinic keratosis