Targeted phototherapy using 308 nm Xecl monochromatic excimer laser for psoriasis at difficult to treat sites

Psoriasis is a chronic inflammatory multisystem disease involving skin and joints affecting 1–3 % of the world population. The 308-nm excimer laser has been recently used in the treatment of psoriasis, especially localized psoriasis of scalp and palm and soles. The objective of the study is to evaluate the therapeutic efficacy and safety of a 308-nm excimer laser for the treatment of scalp and palmoplantar psoriasis. A total of 41 adult patients (25 males and 16 females) were enrolled in this study, of which 26 patients had lesions localized to scalp, and 15 patients had involvement of palm and soles. The mean age was 44.5 years (range 18–73). And, the mean duration of psoriasis in our patients was 15 years. They were treated with a 308-nm excimer laser. The initial dose was based on multiples of a predetermined minimal erythema dose, twice weekly for a maximum 12 weeks. Twenty-two of the 23 patients with scalp psoriasis showed improvement, while one patient showed no change; none experienced worsening of symptoms. The mean minimal erythema dose (MED) was found to be 383 mJ/cm² (range 180–650 mJ/cm²). The cumulative dose of irradiation was 1,841 mJ/cm² (range 600–2,500). The percentage improvement from baseline in PSSI score was 78.57 %. Side effects were seen in 20 patients (86.96 %) mainly in the form of erythema. Four patients developed mild relapse at the end of 6 months after the therapy. In 15 patients with palmoplantar psoriasis, the mean MED was found to be 415 mJ/cm² (range 200–950 mJ/cm²). The cumulative dose of irradiation was 28.4–115.5 J cm² (mean 59.1 J cm²). The mean number of treatments to achieve clearance (equal to 90 % reduction of PSI score) was 16. Two patients relapsed at the end of 6 months after the therapy. The 308-nm excimer laser is an effective, safe, easy, and relatively quicker method for the treatment of psoriasis at difficult to treat sites, with good results in a somewhat short time.