Palmoplantar pustulosis (PPP) is a chronic inflammatory skin disease effectively treated by some phototherapy. UVA1 phototherapy has been widely applied to treat T cell-mediated skin disorders such as atopic dermatitis and cutaneous T-cell lymphoma, and connective tissue disorders. However, UVA1 availability is limited, perhaps due to the relatively high energy consumption and heat generation. Therefore, a light-emitting diode (LED) that emits UVA1 will be a more desirable and feasible light source, particularly if it has a high enough intensity level to treat skin diseases. Here, we successfully treated PPP using UVA1-LED phototherapy. A retrospective observational study was conducted from August 2019 to September 2020. In this study, a new treatment device (modified based on the TheraBeam® UV-N, USHIO INC, Tokyo, Japan) incorporating LEDs rather than methyl halide lamps were used. This device emits a peak wavelength of 365 nm UVA1 and utilizes a short wavelength cut-off filter to reduce excessive immediate tanning theoretically. As a result, 9 of 13 patients showed amelioration of PPP lesion, and PPSI was decreased significantly by UVA1-LED irradiations (N=13, one-way ANOVA p<0.0001, additional statistics by Wilcoxon matched-pairs signed-rank test; ** p=0.0044). The pustular 0-1achievement was 46.2% (week1) and 76.9% (week5). In conclusion, the newly developed UVA1-LED device provided therapeutic effects for PPP. No safety concern was found. There are good features of UVA1-LED phototherapy including no requirement of 8-methoxypsoralen and unnecessary to avoid sunlight after the treatment.

ESDR074 - Successful treatment of palmoplantar pustulosis by UVA1-LED phototherapy

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING