Differential expression of CK7, CK20, CDX2 in intestinal and pancreatobiliary types of preriampullary carcinoma

Context: Incidence of periampullary carcinoma is low, approximately 0.5–2% of all gastrointestinal malignancies. Histologic subtyping has a prognostic bearing. The purpose of this study is to differentiate periampullary carcinomas based on immunohistochemistry (IHC) by using cytokeratin 7 (CK7), cytokeratin 20 (CK20), caudal type homeobox 2 (CDX2). Aims: To analyze the usefulness of IHC as single/panel of markers that included CK7, CK20, and CDX2. Settings and Design: This was a prospective study done from January 2017 to September 2018. Subjects and Methods: A total 50 pancreaticoduodenectomy specimens were evaluated and classified as intestinal (INT) and pancreaticobiliary (PB) types based on their morphological and immunohistochemical features, respectively. The morphologic subtypes, expression of IHC markers were correlated with different histologic parameters. Statistical Analysis: Chi-square test was used to study the association between different IHC markers with histologic parameters. Probability (P) values <0.05 were regarded as statistically significant. Results: The expression of CK7, CK20, CDX2 were studied in 50 cases to classify them as INT and pancreatobiliary subtypes. CK7 has high sensitivity (88.2%), CDX2 has high specificity (96.4%), CK20+/CDX2+ has both high sensitivity (94.2 percent) and specificity (89.2 percent) in differentiating INT from pancreatobiliary subtypes. The morphologic subtypes showed correlation with two variables (tumor grade, pathologic T stage). CK20 and CK20/CDX2 expression showed a positive correlation with tumor grade, pathologic T staging, and lymphovascular invasion. Conclusions: In conclusion, morphological classification can significantly discriminate histologic types, IHC plays a moderate role. However, the combined expression of CK20 and CDX2 is helpful in subtyping.