Pityriasis Versicolor (PV) is a common superficial fungal infection of the skin caused by an unusual increased proliferation of Malassezia species of the stratum corneum layer of skin. Malassezia is a yeast that is part of the skin's habitual flora and it adquires a pathogenic potential when assuming the mycelial form under the influence of trigger factors including humidity, immunosuppression and hiperhidrosis. Systemic therapies are recommended for severe or recalcitrant cases, but they could come with 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. This study aimed to evaluate the effect of a PDT mediated by methylene blue(MB) in extensive PV. Five women with extensive PV disseminated on the back and diagnosed by fresh microscopic analysis, were treated with an aqueous solution of MB (2%) applied to the PV lesions for 3 minutes. Then, a red LED lamp, with narrow spectrum light of 630 nm and fluence of 37J/cm2, placed 100 mm from  the skin during 10 minutes, was applied on the dyed PV lesions. Control in situ of the healing process was carried out by Wood's lamp. Complete cure (clinical cure -by dermoscopic images- and mycological cure -by microscopic examination-) was observed in the five women at the 4-month follow-up. No patient showed relapse at the 6-month follow-up. The patients did not have any adverse effect or pain and good cosmetic outcome was observed. Six sessions of MB/PDT spaced at 14-day intervals are sufficient for the treatment of extensive PV in non-immunocompromised patients.

Successful treatment of extensive Pityriasis Versicolor by Photodynamic Therapy mediated by methylene blue