It's no use. This kind is due to skin degradation, pigmentation appears brown or black, which makes people willing to get sick. At present, there is no scientific explanation (just like why people die of old age, the reason has not been found). At present, this kind of external medicine is incurable, and there is no internal medicine. However, you can eat more fish, red dates and corn, which can relieve discomfort within a week. If you feel seriously uncomfortable, eating notoginseng is very effective. Interventional therapy can be considered, such as CO2 laser, electric ion cautery, freezing, grinding, skin grafting, skin degeneration and so on. There is no evidence that it will lead to other complications. To put it bluntly is ugly.