Melasma (Chloasma, Pregnancy Mask): Why is it so difficult to treat ?

• One of the reasons to this therapeutical frustration is due to the lack of understanding of the pathogenesis of melasma (chloasma, pregnancy mask).
• Although triggering factors (ultraviolet light, pregnancy, oral contraceptives) and immunohistochemical properties of melasma are well known, molecular and genetic mechanisms which are involved a poorly understood.
• Scientific Consensus says the following about melasma: Melasma is not a purely melanocytic problem but a dysfunctioning “systems biology”, which affects the complex interaction of keratinocytes, melanocytes, fibroblasts and dermal blood vessels; this leads to hyperpigmentation.
• Targeting melanin synthesis by melanocytes is not enough to lighten melasma. Indeed, treatment with hydroquinone only often yields disapointing results. The combination of hydroquinone, a steroid and tretinoin only partially improves effficacy (refractory melasma) but prevent melasma from coming back.

Contributors:

Dr Christophe HSU – dermatologist. Geneva, Switzerland

Source of Information: Goh BK. The Science Behind Pigmentary Disorders.  NSC Dermatology Update 2012, Singapore

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