Get the Facts Melasma is a condition characterized by brown patches on the skin, which appear on the face, neck, chest, or arms. The melanocytes (cells that give skin color) overproduce melanin in the skin, resulting in a patchy appearance of dark pigment, most often on the upper lip, forehead or cheeks. Women tend to be affected more than men, as well as people with a family history of melasma or people of certain ethnic backgrounds. While the exact cause of melasma is unknown, sun exposure and hormonal changes, such as pregnancy, usually trigger and/or worsen melasma. Melasma is a treatable condition, however, it often requires continuous preventative measures to keep symptoms under control.