Clinical and histologic evaluation of psoriatic plaques treated with a flashlamp pulsed dye laser

Background: Psoriatic plaques can be cleared by destruction of the dermal papillae. Dilated vessels, the major component of psoriatic dermal papillae, can be selectively destroyed with yellow light lasers. Previous investigators have demonstrated partial clearing of psoriatic plaques after treatment with a pulsed dye laser (PDL) (585 nm). Objective: This study was designed to examine the clinical and histologic events of psoriasis treated with the PDL. Methods: Psoriatic plaques were treated with a short (450 mu sec) and long (1500 mu sec) pulse-width PDL. Photographs of the plaques were used for clinical assessment. Biopsy specimens were examined microscopically. Results: Significant clinical improvement was seen, and no significant difference between the long and short pulsewidth lasers was found. Patients responding to treatment with the PDL remained in remission for up to 13 months. Histologic normalization occurred after treatment. Two pretreatment vascular patterns were seen: vertically oriented vessels with few horizontal vessels and numerous tortuous vessels. Tortuous vessels were associated with poor clinical results. Conclusion: The PDL can induce prolonged remission in chronic plaque psoriasis. The vascular pattern may help to distinguish those patients likely to respond to this treatment.