Abstract
BACKGROUND: Skin pigmentary changes of pityriasis versicolor may occur as either hyperpigmented or hypopigmented lesions, depending on the outcome of interactions between Malassezia yeasts and the skin, such as lipoperoxidation process, stimulus of inflammatory cell to melanocytes, and increased thickness of keratin layer. OBJECTIVE: To investigate skin characteristic factors that enhance the susceptibility to Malassezia yeasts and provoke different color changes of pityriasis versicolor patients. METHODS: To clarify these factors, we investigated the skin characteristics of pityriasis versicolor patients, using a non-invasive method known as MPA 5® (Courage and Khazaka, Germany). A total of 90 normal healthy subjects and 30 pityriasis versicolor patients were included in this study. RESULTS: Both hyperpigmented and hypopigmented pityriasis versicolor skin lesions showed higher humidity, increased sebum excretion rate and increased transepidermal water loss (TEWL) values than normal healthy subjects. But no significant difference of specific Malassezia yeasts species between hyperpigmented and hypopigmented skin lesions was evident. CONCLUSION: These results indicate that higher humidity and increased sebum level provide a better growing environment of Malassezia yeasts in the skin, leading to the assumption that interaction between Malassezia yeasts and skin barrier materials makes disruption of skin barrier causing increased TEWL.