Suddenly there is a piece of white skin may be associated with vitiligo, pityriasis alba and lichen planus, and the treatment methods are medication, laser treatment and so on. 1. Vitiligo: due to the epidermal dermal junction melanocyte tyrosinase function is impaired, melanin production obstacles lead to the appearance of varying sizes of white patches of skin. You can carry out medication, give glucocorticoid preparations, such as halomethasone ointment; or calcium-modulated phosphatase inhibitors such as tacrolimus ointment and other treatments. And auxiliary irradiation 308nm excimer laser and other physical therapy. 2. White chaff rash: white chaff rash is self-limiting, the use of medication can shorten the course of the disease. Oral vitamin B complex, local choice of emollient cream, such as vitamin E milk. 3. lichen planus: fungi cause local hypopigmentation. Treatment choice of local antifungal drugs, such as miconazole cream, ketoconazole lotion; larger area should be oral itraconazole and other medications, and pay attention to protect the skin clean and dry. If the above symptoms occur, the cause of the disease should be clarified, and follow the doctor’s instructions for medication.