Melasma.

Melasma is a common disorder of hyperpigmentation that is present most commonly in reproductive age women with brown or black skin colors. The lesions of melasma are characteristically distributed in a symmetric manner on the sun-exposed areas of the face and neck. The precise pathogenesis of the disorder is unknown, but a number of etiologic agents have been implicated as its cause. These include ultraviolet radiation, hormonal alterations such as those evident during pregnancy, thyroid dysfunction, and phototoxic and anti-seizure drugs. The pathophysiology of melasma is believed to involve excess production of melanin or an increase in the number of melanocytes in the skin. This is confirmed by histological analysis of melasma, which shows an increased number of melanocytes along with an enhanced capability of these cells to produce melanin. Lack of an understanding of the precise pathogenesis of the condition has led to a large number of treatments for melasma. These therapies include hypopigmenting agents, chemical peels, lasers, and dermabrasion. Further investigations into this disorder may lead to more specific and effective treatments in the future.