1Department of Gastroenterology, Sichuan Mianyang 404 Hospital, Mianyang City, Sichuan Province, China;

2Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, Sichuan, China;

3Department of Pathology, Sichuan Mianyang 404 Hospital, Mianyang City, Sichuan Province, China.

Correspondence: Yanhui Mao, MD. E-mail: [email protected].