Melasma is brownish patches commonly appearing on the cheeks, chin, forehead, nose, and upper lip. Melasma begins as an irregular brownish flat spot (macules), then slowly spreads out, forming brownish patches. Commonly known as the mask of pregnancy, chloasma is melasma acquired during pregnancy. Melasma is thought to be caused by a complex interaction of a number of factors including sun-exposure genetics and hormones. Although some melasma may disappear spontaneously after menopause, melasma generally does not regress on its own and is one of the most resistant pigmentations to treat. Traditionally, combination of topical agents such as hydroquinone, retinoic acid, and steroids has been used to treat melasma. These topical treatments result in only temporary clearing in some patients, with the possibility of melasma flare-ups and long-term complications.
Melasma is typically grouped into three large categories based on the depth of melanin pigments; epidermal melasma (pigments in superficial layers), dermal melasma (pigments in deep layers), and mixed type (pigments in both superficial and deep layers), but this classification is based on a flawed study that was conducted more than two decades ago. Clinically more relevant classification should be based on known histological changes (microscopic changes within the skin).