Clinical and dermoscopic response predictors in psoriatic patients undergoing narrowband ultraviolet B phototherapy: results from a prospective study.

BACKGROUND: Although disease severity, gender, body weight, and previous treatments have all been reported to affect clinical response of psoriasis vulgaris to narrowband ultraviolet B (NB-UVB) therapy, little information about possible local (lesional) influencing factors is available. OBJECTIVE: To assess correlations between clinical/dermoscopic findings of psoriatic plaques and therapeutic response to NB-UVB phototherapy in order to find positive and/or negative response predictor factors to such a treatment. METHODS: For each target lesion, we calculated local psoriasis severity index and assessed dermoscopic findings at the baseline. After 8 weeks of treatment, we evaluated clinical improvement of each lesion, correlating the therapeutic outcome with initial clinical and dermoscopic features. RESULTS: Ninety-eight target lesions from 27 patients were included in the study. After 8 weeks of therapy, 31 lesions experienced no/limited improvement, while partial response was observed in 40 plaques and optimal response in 27 lesions. Regarding clinical variables, we found an association between poor therapeutic outcomes and both legs localization and more marked lesion scaling/infiltration. Similarly, globular vessels on dermoscopy were more commonly associated with no/limited response as well as lesions localized on the legs, particularly those showing treatment resistance. Conversely, the presence of dotted vessels carried a higher probability for getting improvement. CONCLUSION: Therapeutic response of psoriasis vulgaris to NB-UVB treatment may be negatively affected by local clinical factors, that is, significant scaling/infiltration and legs localization, and dermoscopy may be useful in highlighting possible response predictors, with globular and dotted vessels associated with bad and good outcomes, respectively.