Excimer Light Phototherapy for Refractory Lesions of Atopic Dermatitis in Japanese Patients

Abstract

　Multiple studies have reported that excimer light phototherapy is effective for psoriasis, leukoderma, and other skin disorders. However, a safe and practical irradiation method for atopic dermatitis has not been established. In this study, targeted irradiation therapy using excimer light was performed using TheraBeam UV 308 (Ushio, Tokyo, Japan) against refractory pruritic lesions of atopic dermatitis at a dermatology clinic. The minimal erythema dose (MED) was not determined individually but was assumed to be 307 mJ/cm², as the mean MED for Japanese patients. The initial dose was approximately 100 mJ/cm² (1/3 MED) , but was adjusted to 1/4 MED for the face and children, and to 1/2 MED for the palmoplantar region and lichenoid lesions.

　Results : Of the 322 patients, complete remission was observed in 46 (14%) , and partial remission was observed in 154 (48%) , after 1 or 2 irradiation sessions. No adverse effects were observed, except that a 28-year-old man exhibited mild erythema for a few days. In 40 children aged 6 years or younger, complete remission was observed in 15 (38%) , partial remission in 16 (40%) , and no remission in 2 (5%) . No aggravation was obserred. In some patients, pruritus disappeared within 1 hour after irradiation, presumably because excimer light directly induced epidermal nerve degeneration. Excimer light phototherapy was sufficiently effective for refractory lesions of atopic dermatitis. In Japanese patients, it is safe to begin irradiation at a low dose (1/3 MED) using an irradiator with a filter function to exclude cytotoxic wavelengths.