Use of the 308-nm excimer laser for psoriasis and vitiligo.

The 308-nm excimer laser represents the latest advance in the concept of selective phototherapy. It emits a wavelength in the UV-B spectrum and thus shares the same indications as conventional phototherapy. Like other laser devices, the 308-nm excimer laser emits a monochromatic and coherent beam of light, can selectively treat a lesion while sparing surrounding healthy skin, and can deliver high fluencies. Clinicians have taken advantage of these properties to treat dermatologic disorders since 1997, with psoriasis and vitiligo attracting most attention. Initially, high fluencies (minimal erythemal dose, 8-16) were used, with excellent clinical results, to treat psoriasis vulgaris. The significance of side effects and the potential long-term carcinogenic risk associated with such fluencies have resulted in medium doses (about 3 minimal erythemal dose) being recommended, however. Interestingly, taking advantage of the selectivity of the laser, newer treatment protocols adapt the dose to the lesion and not to the minimal erythemal dose, as is the case for conventional phototherapies. Many prospective study series have also shown the efficacy and the good tolerance of the 308-nm excimer laser in the treatment of localized vitiligo. Induced rates of repigmentation seem to be higher than with narrowband UV-B. Moreover, the selectivity of the treatment prevents irradiation of healthy skin and limits unsightly tanning of surrounding skin. Aesthetically pleasing results are usually not achieved in extremities and bony prominences, which are not good indications for this technique. Combining the 308-nm excimer laser with 0.1% tacrolimus ointment has provided very interesting results, which need to be confirmed in larger series. The absence of actual data concerning the long-term risk for skin cancer after this treatment means that it should be considered with caution. Combination with topical steroids appears to be synergistic and potentially reduces long-term side effects; again, prospective data are lacking.