Role of CDX2 immunostaining in diagnosis of gastrointestinal adenocarcinoma

Abstract

To study the expression of CDX2 in normal and tumor tissues, and to evaluate the value of CDX2 immunostaining in the diagnosis of gastrointestinal adenocarcinoma. Seventy-six samples of normal tissue and 612 samples of tumor tissue were studied by tissue microarray technology and immunohistochemistry for CDX2. CDX2 was strongly expressed in surface epithelium of 13 samples of normal intestine and in ductal epithelium of 8 samples of normal pancreas, as well as in 47 samples (92.2%) of colonic adenocarcinoma and 58 samples (66.9%) of gastric adenocarcinoma. As for other tumor types, there was only weak or patchy CDX2 positivity. The positivity rates were as follows: ovarian mucinous adenocarcinoma 15.6% (10/64), pancreatic cancer 33.3% (3/9), thyroid cancer 27.3% (3/11) and extrahepatic biliary cancer 25% (4/16). On the other hand, primary tumors of breast, prostate, kidney, adrenal and liver were negative for CDX2. CDX2 is expressed mainly in normal epithelium of intestinal tract and small pancreatic ducts, as well as in primary adenocarcinoma of gastrointestinal tract. CDX2 may thus play an important role in distinguishing primary non-intestinal adenocarcinoma from metastatic adenocarcinoma of gastric or colorectal primary.