1. Department of Gastrointestinal Surgery, the Affiliated People’s Hospital of Ningxia Medical University, Yinchuan, Ningxia 750001,China
2. Department of Pathology, Ningxia Medical University, Yinchuan, 750004 China
3. Department of Pathology, the Affiliated People’s Hospital of Ningxia Medical University, Yinchuan, Ningxia 750001,China
4. Department of Gastroenterology, Henan No.3 Provincial People\'s Hospital, Zhengzhou, 450000 China