UVA blocking effect of epidermal melanin in patients with vitiligo

Abstract

Background: Ultraviolet light induces sunburn, aging of the skin, disorders of pigment and even promotes skin cancers. Melanin is known to have a protecting role in the skin by blocking ultraviolet light. Objective: The purpose of this study was to evaluate UVA blocking effect of epidermal melanin and to compare UVA blocking effect among different anatomical sites. Method: From 20 vitiligo patients who had undergone an epidermal graft, we obtained epidermis of normal and vitiliginous skin and measured transmitted UVA energy density. Results: The vitiliginous epidermis, devoid of melanin, blocked lower amount of UVA energy than the normal epidermis. 11.6% of irradiated UVA energy was blocked by epidermal melanin. No significant differences were observed in UVA blocking effect among different anatomical sites in-normal and vitiliginous epidermis. Conclusion: Epidermal melanin has some UVA blocking effect. No significant differences were found in UVA blocking effect among different anatomical sites despite the differences in the density of melanin pigment among different sites of the body.