Special parts of the skin are easily rubbed and often attacked by viruses and bacteria, and melanocytes are damaged and die. Melanocytes form epidermal melanin units with peripheral keratinocytes. Due to the death of melanocytes, keratinocytes in melanin units lose the melanin source, and white spots appear on the skin.

Huahai Vitiligo Hospital's "Black and White Tongzhi" technology selects characteristic Chinese medicines to stimulate keratinocytes in epidermal melanin units, producing special melanocyte chemokines, growth factors and adhesion factors, so that melanocytes and white spots in the basal layer of the leukoplakia remain. The surrounding melanocytes activate and proliferate and accumulate in the leukoplakia, and produce melanin, which makes the leukoplakia complex.