Melasma (Chloasma)

Overview

Melasma is a kind of hypermelanosis of sun-exposed skin that occurs during pregnancy and affects 50-70 percent of pregnant women. It manifests as symmetric hyperpigmented macules that can be confluent or punctuate. The cheekbones, upper lip, chin, and forehead are the most commonly affected areas. The precise method through which pregnancy influences melanogenesis is uncertain.

During the third trimester of pregnancy, estrogen, progesterone, and melanocyte-stimulating hormone (MSH) levels are generally elevated. Nulliparous patients with chloasma, on the other hand, do not have elevated estrogen or MSH levels. Melasma has also been linked to the use of estrogen- and progesterone-containing oral contraceptives.

The finding that postmenopausal women administered progesterone develops melasma whereas those given just estrogen do not suggest that progesterone plays a significant role in the formation of melasma.