Why is vitiligo easily caused by summer sun exposure? According to recent research, vitiligo is 80 percent related to seasonal factors, especially in late spring and early summer, when white spots are more likely to occur or increase the number of new white spots. So why is this a phenomenon? It is possible that the sunlight has catalyzed vitiligo? Especially after sun exposure, melanocytes are damaged, its tyrosinase and dopa oxidation intermediate substances also appeared problems, intermediate substances is an important protective mechanism, once this protective mechanism consumption decline, melanin will be destroyed; Secondly, it may be due to the cell itself can synthesize melanin intermediate substances overproduced or accumulation and damage to the melanocytes, so that the white spots occur. The world about vitiligo survey data performance, the incidence of vitiligo in the dark-colored skin population can be as high as 4% (such as India), and light-colored people less than 1% (such as the United States, Britain), the incidence of the two differences are significant. The reason for this is not well understood. But may be synthesized with the mature melanosomes (that is, phase IV melanin) morphologically different, manifested in the following aspects. 1, melanosomes in the keratinocyte degradation (melting, disappearance) process is also different. Light skin species keratinocyte melanosomes most of the keratinocyte lysosomes in the direct action and degradation; in the black race, keratinocyte melanosomes are mainly after a degradation pathway, that is, diffuse to the epidermal layers, and finally with the shedding of the stratum corneum and the separation of the epidermis, which is why the darker skin species of darker skin color. 2, dark skin type of melanin anabolism may be more exuberant, if once given ultraviolet activation factors, melanin anabolism will be extremely exuberant, so it will accelerate the consumption of melanocytes; due to the exuberance of melanin metabolism, the excessive accumulation of intermediary products in turn can kill the melanocytes, thus impeding the synthesis and metabolism of melanocytes and the occurrence of depigmented lesions. 3, light-colored skin types of black body color is relatively light, small size, oval, into a collection of distribution, that is, a few melanosomes wrapped together; dark skin types of melanosomes on the contrary, dark brown color, volume, spherical, a single-type distribution, that is, the melanosomes exist individually. 4, melanosomes from melanocytes transferred to the adjacent keratinocytes, light-colored skin species melanosomes are mainly seen in the epidermis of the basal low layer and echinocyte layer, while dark-colored skin species of the epidermis can be seen in all layers of melanosomes. Through the above content, we understand why summer sun exposure is easy to trigger vitiligo, its tyrosinase and dopa oxidation intermediates are destroyed and the cell itself can synthesize the intermediates of melanin excessive production or accumulation and damage to melanocytes.