PMS2 is a mismatch repair gene in the nucleus, positive in the nucleus of normal colonic mucosal cells, with loss of expression after mutation. Combined testing for MLH1, MSH2, PMS2 and MSH6 can be used to screen for Lynch syndrome (hereditary nonpolyposis colon cancer). 1. Almost all positives (≥95% of cases) are likely to be sebaceous adenocarcinoma, sebaceous adenoma, juxtaglomerular adenocarcinoma, intestinal type, clear cell renal cell carcinoma, sebaceous epithelial tumor, endometrial clear cell carcinoma, juxtaglomerular adenocarcinoma, pancreaticobiliary type, and juxtaglomerular carcinoma. 2. Usually positive (<95%, ≥75% of cases positive) may be colorectal adenocarcinoma, endometrial adenocarcinoma, small bowel adenocarcinoma, endometrial plasma carcinoma, colorectal adenocarcinoma, familial polyposis-associated, pancreatic ductal adenocarcinoma. 3. A few positives (<35%, ≥15% of cases positive) may be colorectal lymphoepithelioma-like carcinoma. 4. Almost all negative (<5% of cases positive) may be undifferentiated carcinoma of the esophagus. If there is any abnormality, it is recommended to cooperate with the doctor to further improve the examination.