The occult insulinoma was localized using endoscopic ultrasound guidance：A case reportZhongqiu Guo1 Yanrong Chen1 Ronghuo Liu1 Yuhua Chen11Department of Endocrinology and Metabolism, Longgang District People’s Hospital of Shenzhen,The Second Affiliated Hospital of The Chinese University of Hong Kong, Longgang central city, Shenzhen, Guangdong, P.R. China.Corresponding Author:Yanrong Chen, Longgang District People’s Hospital of Shenzhen,The Second Affiliated Hospital of The Chinese University of Hong Kong, Longgang central city, Shenzhen, Guangdong, P.R. China.E-mail: Yanrong Chen@126.com