CDX-2 A plus sign indicates CDX-2 positivity, which may be associated with diseases such as reflux esophagitis, infection with Helicobacter pylori, intestinal-type gastric cancer, rectal cancer, and ovarian mucinous adenocarcinoma. CDX-2 is an intestinal-specific transcription factor, an intestinal epithelial-specific gene, which is mainly expressed in the small intestine and colorectum in gastrointestinal tumors, and serves as a differential indicator of the primary site of the tumor. Normal adult intestinal epithelial cells generally rarely express CDX-2, and if positive expression exists, it may be related to reflux esophagitis, Helicobacter pylori infection, intestinal gastric cancer, rectal cancer, ovarian mucinous adenocarcinoma, and other diseases. It is known that more than 95% of invasive colorectal cancers are positive for CDX-2, while gastric cancers and ovarian mucinous adenocarcinomas may also be positive for CDX-2. Therefore, once CDX-2 positivity occurs, it is necessary to go to the hospital for examination in time, and identify the primary site of the tumor by combining with CK7, CK20 and other indexes, so as to clarify the specific cause of the disease, and actively treat it under the guidance of the doctor.