Clues to the Pathogenesis of Melasma from its Histologic Findings

Melasma is an acquired hypermelanosis characterized by the development of symmetrical, irregular light-to-dark brown macules and patches on sun-exposed areas of the skin, especially on the skin of the face [1]. It is common among Asian and Hispanic women who are in their third or fourth decades of life [2]. Three patterns of melasma are recognized clinically that are based on the distribution of the hyperpigmentation on the face, namely, the centrofacial, malar, and mandibular patterns. However, melasma often presents as a mixture of these patterns. Factors involved in the pathogenesis of melasma include a genetic predisposition, chronic exposure to ultraviolet (UV) radiation, and female sex hormones [3-6]. However, the pathogenesis of melasma has not yet been fully elucidated.