Psoriasis is a disease in which epidermal keratin-forming cells divide and increase excessively. Normal epidermal cells are metabolized every day for 28 days, so cells are shed every day, but because the amount is small, and because the skin is moistened it is not easy to notice, but in psoriasis lesions, this cycle is only 3-4 days, the cells divide too quickly and the growth cycle is significantly shortened, which means that their epidermal cells are pushed to the This immature cells are loosely bonded to each other, unlike the normal skin stratum corneum, which is neatly arranged and tightly packed with a large amount of air in the interstices, and can present a silvery white appearance under the refraction of light. Therefore, layers and layers of mica-like loose white flakes and silvery-white snowflakes are seen on psoriasis patients. The epidermis normally seen by the naked eye is the stratum corneum. The keratinocytes are dead when they reach the stratum corneum and have no cellular structures such as nuclei and organelles, so they have no ability to reproduce and proliferate. However, this lifeless stratum corneum has a very important protective role for the human body. With normal cellular metabolism, the stratum corneum is continuously shed to maintain a biological dynamic balance. There are fixed times for various normal cell growth cycles. It has been recognized through cytological, histological, and biochemical studies that in psoriatic skin damage, the epidermis grows considerably faster than normal skin. In the cell growth cycle of normal epidermis, the transition time for basal cells to grow to the surface is approximately 28 days, whereas in psoriatic lesions it is shortened to 3-7 days. The growth cycle of normal epidermal cells is 457 hours, while in psoriasis it is only 37.5 hours. The stratum corneum, the combination of this immature cells with each other is loose, unlike the stratum corneum of normal skin, which is neatly arranged and tight, with a large amount of air interspersed within its interstices, which can present a silvery-white appearance under the refraction of light, and also because of the loose combination, the barrier protection function of the skin is lacking or reduced, and it can be easily scratched off and scraped off, therefore, layers and layers are seen on psoriasis patients Mica-like loose white flakes and flurries of silvery white snowflakes are seen on the psoriasis patient. The epidermis of a psoriasis patient is proliferating abnormally fast, and the spiny cell layer consists of many layers of active cells, which can be observed under a light microscope as hypertrophic, with increased cell size and layers, forming patches of psoriatic flakes. A large number of keratinocytes grow vigorously and soon become loose stratum corneum, which thickens, builds up and sheds a large number, forming the silvery-white psoriatic flakes seen clinically. This is the reason why psoriasis patients have a very large amount of dander at the lesion site.