Oestrogen and progesterone receptor expression in melasma: an immunohistochemical analysis

Background Melasma is a commonly acquired symmetrical hypermelanosis on sun-exposed areas of the skin. The development of melasma appears to be associated with increased levels of oestrogen, exposure to sunlight and a genetic predisposition. Several in vitro studies have partially clarified the effects of oestrogen and progesterone on melasma. However, oestrogen receptor (ER) and progesterone receptor (PR) expression in melasma-affected skin has not been investigated to date, except for one case report on ER expression. Objective The purpose of this study was to compare ER and PR expression between hyperpigmented areas and unaffected areas of facial skin in patients with melasma. Methods Biopsies were performed on skin lesions and adjacent-unaffected facial skin in 33 Korean women with melasma. The sections were stained using haematoxylin and eosin, Fontana-Masson, and antibodies to NKI/beteb, ER alpha, beta and PR. Results The immunohistochemical expression of ER beta showed an increasing tendency in epidermal lesions without statistical significance. Expression of PR was significantly increased in the epidermal lesions compared with unaffected skin on the computer-assisted image analysis. Interestingly, there was increased ER beta expression in the dermal lesions especially around small blood vessels and fibroblast-like cells compared with unaffected dermis on the semi-quantitative analysis. However, there was no significant difference in the expression of PR between the dermal lesions and unaffected dermis. Conclusion The results of this study may provide useful information for further investigation into the pathogenesis and therapeutic approaches for treating melasma in relation to hormonal factors. The role of ER in the dermis in association with dermal environment such as blood vessels and fibroblasts remains to be further clarified.