308 nm monochromatic excimer light in dermatology: personal experience and review of the literature.

RESULTS: For over five years, we have been using a new ultraviolet B ray source, a Xenon-Chloride lamp emitting non-coherent, monochromatic 308-nm light that represents the natural evolution of the excimer laser. A source of monochromatic excimer light (MEL) produces 50 mW/cm(2) power density at a distance of 15 cm from the source and has a maximum irradiating area of 504 cm(2), this feature representing the greatest therapeutic advantage offered by 308 nm sources. On the other hand, the benefits offered by the MEL compared to traditional phototherapies are essentially correlated to the fact that there is no need to administer oral psoralens (PUVA therapy) and that sessions need to be repeated only every 7-15 days, an important condition for the improvement of the patient's quality of life (since at least 2-3 weekly sessions are required with the traditional UVB therapy). Using MEL, UV B light can be applied on the entire body, with partial subintrant skin irradiations, or on one or just a few individual patches, taking care to accurately protect the healthy surrounding skin and allowing for a phototherapy exclusively targeted onto the lesion to be treated. Clinical indications and the reasons for choosing MEL for the treatment of photosensitive skin disorders are virtually identical to those stated for PUVA therapy or narrowband UV B light. Due to the absence of photosensitizing substances and drug-induced toxicity, patients who work in the open air, pregnant women and patients suffering from liver or kidney failure can also be treated. Furthermore, the short time required for sessions, the duration of cycles and the selective exposure of the skin areas to be treated undoubtedly represent significant benefits for patients in terms of safety and efficacy. In addition to psoriasis, the use of MEL can also be extended to other pathologies such as vitiligo, alopecia areata, atopic dermatitis and patch-stage IA mycosis fungoides with encouraging