RESUMEN
BACKGROUND: Phototherapy is a traditional treatment for psoriasis and patients using it for a long time may be exposed to cumulative toxicity, so dermatologists need continuously diagnostic tools that help in monitoring the disease progression. OBJECTIVES: To detect dermoscopic changes with the improvement of skin in patients with chronic plaque psoriasis on narrow-band ultraviolet B phototherapy and evaluate the role of dermoscopy in monitoring the patients. METHODS: Narrowband ultraviolet B phototherapy was prescribed to thirty (30) patients with chronic plaque psoriasis for three months according to their disease condition. Psoriasis area and severity index (PASI score) were calculated, and dermoscopic evaluation was done at the first visit (W0), after 6 weeks, and after 12 weeks of beginning the phototherapy. RESULTS: According to PASI score calculations, a significant correlation was found between changes in the vessel patterns and the improvement that occurred during the treatment sessions in psoriatic lesions, whereas the patients with globular blood vessels were significantly associated with weak clinical results. CONCLUSION: Dermoscopy is a rapid, simple tool to predict the response of psoriatic patients to phototherapy using vascular pattern assessment.