Chloasma is a common acquired skin pigmentation disorder in clinical practice. It mostly occurs in women of childbearing age, and can also be seen in less-known men. It is characterized by symmetrical pigmentation on the cheeks, forehead and cheeks, mostly in the shape of butterfly wings. Light yellow or light brown, heavy dark brown or light black.
Almost all racial and ethnic minorities can develop the disease, but areas with intense UV exposure, such as Latin America, Asia, and Africa, have a higher incidence. Most of the patients develop disease in their 30s and 40s, and the incidence in 40- and 50-year-olds is 14% and 16%, respectively. Light-skinned people develop early onset, dark-skinned people develop later, even after menopause. Surveys from small populations in Latin America show an incidence of 4% to 10%, 50% in pregnant women and 10% in men.
According to the location of distribution, melasma can be divided into 3 clinical types, including the mid-face (involving the forehead, dorsum of the nose, cheeks, etc.), zygomatic and mandible, and the incidence rates are 65%, 20%, and 15%, respectively. In addition, some idiopathic skin diseases, such as idiopathic periorbital skin pigmentation, are thought to be associated with melasma. According to the deposition location of melanin in the skin, melasma can be divided into epidermal, dermal and mixed types, among which epidermal type is the most common type, and mixed type is the most likely, Wood’s lamp is helpful for the identification of clinical types. Among them, the epidermal type is light brown under the Wood’s light; the dermal type is light gray or light blue under the naked eye, and the contrast is not obvious under the Wood’s light. Accurate classification of melasma is beneficial to the choice of later treatment.
Post time: May-06-2022
