Can we improve the classification of ampullary adenocarcinoma? The value of histomolecular classification and clinicopathological features on prognosis

ABSTRACT Background Ampullary adenocarcinoma (AA) can originate from three different epitheliums, conditioning its evolution and prognosis. Recently, histomolecular classification has been defined, according to the presence of immunohistochemical (IHQ) markers of intestinal (INT) lineage vs pancreatobiliary (PB). Methods 42 AA patients were retrospectively reviewed and morphologically and molecular classified with IHQ MUC1, MUC2, CDX2, CK20 and CK7 markers, according to the system described by Chang et al. A prognostic study was carried out in relation to histological and histomolecular characterization and other clinicopathological variables. Results 24 patients (57%) were pancreatobiliary (Chang-PB) and 16 (43%) intestinal (Chang-INT), 2 patients could not be classified. The histological classification (post-surgical report vs reviewed) showed a congruence of 75% with a kappa concordance index of 0.595. The Chang-PB molecular classification showed lower survival in all comparisons, but it was not statistically significant (long-rank> 0.05). Univariable analysis showed that only lymph node invasion and CK20 staining were associated with overall survival. Conclusion An IHC classification could improve the prognostic characterization of AA, however, there is a lack of evidence on the clinical importance of molecular markers in AA with conflicting results, and its applicability has yet to be established.