Melasma, also known as liver spots, is a yellowish-brown pigmentation on the face. It is mostly distributed on the cheeks in a symmetrical butterfly shape. It is mostly seen in women, and the high level of estrogen in blood is the main cause. Its onset is related to pregnancy, long-term oral contraceptives and menstrual disorders. Etiology and pathogenesis 1. Ultraviolet radiation: In Hawaii where the sun shines directly all year round, almost all people have chloasma on their faces and arms. The amount of sunlight exposure received in childhood is closely related to the onset of melasma in the future. In general, the body’s ability to resist ultraviolet rays is limited. If you over-expose yourself to sunlight as a child, your ability to resist sunlight will be weakened day by day and will be depleted around the age of 30, showing a variety of photo-aging pigmentation such as melasma, freckles and solar freckle-like nevus. In addition, many ladies or housewives who often sit in the office refuse to use sunscreen, then the ultraviolet rays in the fluorescent tubes, the ultraviolet rays through the window glass and the ultraviolet rays in the mosquito lamp will silently accumulate light damage and eventually form pigmentation; 2. Improper use of cosmetics: if hormones and other ingredients are added in cosmetics in violation of the law, hormone rebound will be formed once the use is stopped, leading to the aggravation of pigmentation that is difficult to control. We often see such patients who undergo spot removal treatment in beauty salons, and the effect is very obvious at the beginning, but after a few months, the skin becomes phenanthrene, sensitive and red bumps appear. Once you stop or change cosmetics you will have red spots, papules, even edema and exudation, which is typical of hormone dependent dermatitis. If functional cosmetics are used too early and too often, they can also cause skin thinning, sensitivity and the formation of discoloration. For example, the redness of the skin of a 20-year-old woman after using a strong anti-wrinkle cream (containing a high concentration of retinoic acid) falls into this category. If the cosmetics used cause skin allergy or intolerance, the skin will always be red, just like seborrheic dermatitis, and post-inflammatory pigmentation will be formed; 3. Pregnancy: also known as gestational spots, which are related to the elevated level of estrogen (photosensitive) and can disappear after delivery. Especially for ladies who insist on sunbathing without umbrella or sunscreen during pregnancy; 4. Neuro-endocrine disorders: such as postpartum and menopausal women. Some people are in a state of long-term mental tension, irritability, uncontrollable emotions, and even insomnia and dreaminess. This state will easily lead to the aggravation of chloasma; 5. Drugs: (such as birth control pills, chlorpromazine, phenytoin sodium, etc.); 6. Imbalance of trace elements, etc.; 7. Certain chronic diseases: (such as gynecological diseases, hepatitis, chronic alcoholism, hyperthyroidism, tuberculosis, visceral tumor, etc.) patients can also occur chloasma.