A Novel Immunohistochemistry Classifier for Ampullary Carcinoma: Highlighting the Prognostic Power of CDX2

Ampullary carcinomas (AC) pose a diagnostic challenge while delineating into their prognostically distinct subtypes, pancreaticobiliary (PB) and intestinal (INT). This study aimed to correlate AC's histomorphological (HE) subtypes with its immunohistochemical (IHC) subtypes and evaluate their prognostic outcome.

This study was conducted in the Department of Pathology at a tertiary care cancer hospital. One hundred cases of ACs in pancreatoduodenectomy specimens were selected. Slides were reviewed for HE subtyping of ACs, including Intra-Ampullary papillary-tubular Neoplasms into HE-PB and HE-INT subtypes. IHCs (MUC1, MUC2, MUC5AC, CDX2 and CK20) were performed. ACs were classified into IHC-PB or IHC-INT types using various IHC schemata. IHC and HE subtypes were correlated using Pearson's Chi-square test. Sensitivity, specificity, positive predictive values, and negative predictive values were calculated for the IHCs. Survival status was analyzed using the Kaplan-Meier survival analysis.

The PB subtype showed a higher pathological tumor stage than INT. Among the various schemas evaluated, the Harthimmer Integrated Liu Layered Scoring system performed best with a significant correlation between HE and IHC subtypes. INT subtypes had better prognostic outcomes than PB subtypes. We found an essential prognostic role of CDX2 in the stratification of ACs.