Successful treatment of Pityriasis Versicolor by photodynamic therapy mediated by methylene blue

Although systemic therapies are recommended for severe or recalcitrant cases of pityriasis versicolor (PV), they are not free of important side effects and drug interactions. Photodynamic therapy (PDT) utilizes the action of singlet oxygen and free radicals produced by a light-activated photosensitizer to kill viruses, bacteria, or fungi. In this study, the effect of a PDT mediated by methylene blue (MB) in PV was evaluated.

Five women with PV disseminated on the back and diagnosed by fresh microscopic analysis were treated with a solution of MB (2%) applied to the PV lesions for 3 minutes. Next, a red LED lamp (λ = 630±5 nm, 37 J/cm² ), placed 100 mm from the skin for 10 minutes, was applied on the dyed PV lesions. Six sessions of MB/PDT were implemented with a 2-week interval in between. Wood's lamp examination was used to monitor fungal infection at each time point.

Complete cure was observed in the five women at the 4 weeks post-treatment follow-up. Fluoresce images from PV lesions by Wood's lamp allowed to evaluate whether the lesions were healed or not at each time point. No patient showed relapse at the 6-month follow-up. The patients did not have any adverse effect, and good cosmetic outcome was observed.

Six sessions of MB/PDT spaced at 14-day intervals are sufficient for the treatment for PV in healthy patients.