Evaluation of the clinical and immunohistological efficacy of the 585‐nm pulsed dye laser in the treatment of psoriasis

Abstract

The 585-nm pulsed dye laser (PDL) therapy is useful for the patients with psoriasis. PDL treatment is based on selective photothermolysis of the dermal vasculature. The objectives of this study were to evaluate the clinical and immunohistological effects of PDL on psoriasis and to examine the association between psoriatic dermal vasculature and the clinical effects. Eleven patients with recalcitrant psoriasis were treated with 585-nm PDL. Biopsy specimens obtained before and after treatment were stained with CD31. All microvessels to the depth of 400 microm from the rete ridge were counted and the internal diameters were measured. The mean percent reduction of plaque severity score was 42. The mean microvessel count decreased significantly from 63 to 35.6 ( P < 0.001). There was a strong positive correlation between the plaque severity score and microvessel number ( P < 0.001) and a strong negative correlation between the microvessel count of an untreated area and degree of the change in the microvessel count after treatment (P = 0.005). The findings of this study suggest that PDL treatment improves psoriasis. Moreover, PDL treatment decreased the number of dermal papillary microvessels. Dermal papillary microvessels are important pathogenetic targets of psoriasis, and PDL therapy, which selectively targets superficial vessels, is therefore a valid therapeutic approach.