308-nm excimer laser for the treatment of psoriasis: induration-based dosimetry

OBJECTIVE: To determine the response of stubborn psoriatic plaques to the 308-nm excimer laser. DESIGN: Controlled study with a before-after design. SETTING: A university-based clinical research center. PATIENTS: Adult subjects with recalcitrant plaque psoriasis that have not responded to other therapies for at least 2 months. INTERVENTIONS: Selected psoriatic plaques were treated with the 308-nm excimer laser. One lesion was left as a control. Each plaque was treated 2 times a week, with an initial dose based solely on the induration component of the modified Psoriasis Area and Severity Index score for that lesion. Subsequent treatments were twice a week with dosage increments up to 50%, based on the change in induration. Four final consolidation doses were given once the induration score was reduced to zero. RESULTS: Eighteen subjects were treated. There were 4 dropouts because of various scheduling problems. In the remaining 14 subjects, 44 plaques received a mean of 10 treatments (range, 4-14). Treatments were quick and well tolerated. The mean cumulative dose was 8.8 J/cm2 (range, 2.2-22.8 J/cm2). Compared with controls, treated plaques showed significant improvement (P<.001). The only adverse event was a mild sunburn-like reaction in 2 subjects after 1 treatment. CONCLUSIONS: Selective targeting of laser-generated 308-nm excimer radiation with this convenient subblistering dosage schedule based on induration allows for individualized treatment plans for each plaque. Clearing of stubborn psoriatic lesions occurs rapidly and safely.