Yin Yang1, Lin Peng1, Yiping Ge1, Tong Lin2. 1. Department of Cosmetic Laser Surgery, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, People's Republic of China. 2. Department of Cosmetic Laser Surgery, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, People's Republic of China. Electronic address: ddlin@hotmail.com.