Intra-ampullary Papillary-Tubular Neoplasm (IAPN): Characterization of Tumoral Intraepithelial Neoplasia Occurring Within the Ampulla: A Clinicopathologic Analysis of 82 Cases

There has been no uniform terminology for systematic analysis of mass-forming preinvasive neoplasms (which we term tumoral intraepithelial neoplasia) that occur specifically within the ampulla. Here, we provide a detailed analysis of these neoplasms, which we propose to refer to as intra-ampullary papillary-tubular neoplasm (IAPN). Three hundred and seventeen glandular neoplasms involving the ampulla were identified through a review of 1469 pancreatoduodenectomies and 11 ampullectomies. Eighty-two neoplasms characterized by substantial preinvasive exophytic component that grew almost exclusively (>75%) within the ampulla (in the ampullary channel or intra-ampullary portions of the very distal segments of the common bile duct or pancreatic duct) were analyzed. (1) Clinical: The mean age was 64 years, male/female ratio was 2.4, and mean tumor size was 2.7 cm. (2) Pathology: The tumors had a mixture of both papillary and tubular growth (each constituting at least 25% of the lesion) in 57%; predominantly (>75%) papillary in 23%, and predominantly (>75%) tubular in 20%. High-grade dysplasia was present in 94% of cases, of which 39% showed focal (75%) high-grade dysplasia. In terms of cell-lineage morphology, 45% had a mixture of patterns. However, when evaluated with a forced-binary approach as intestinal (INT) versus gastric/pancreatobiliary (GPB) based on the predominant pattern, 74% were classified as INT and 26% as GPB. (3) Immunohistochemistry: Percent sensitivity/specificity of cell-lineage markers were, for INT phenotype: MUC2 85/78 and CDX2 94/61; and for GBP: MUC1 89/79, MUC5AC 95/69, and MUC6 83/76, respectively. Cytokeratin 7 and 20 were coexpressed in more than half. (4) Invasive carcinoma: In 64 cases (78%), there was an associated invasive carcinoma. Size of the tumor and amount of dysplasia correlated with the incidence of invasion. Invasive carcinoma was of INT-type in 58% and of pancreatobiliary-type in 42%. Cell lineage in the invasive component was the same as that of the preinvasive component in 84%. All discrepant cases were pancreatobiliary-type invasions, which occurred in INT-type preinvasive lesions. (5) OUTCOME: The overall survival of invasive cases were significantly worse than that of noninvasive ones (57% vs. 93%; P=0.01); and 3 years, 69% versus 100% (P=0.08); and 5 years, 45% versus 100% (P=0.07), respectively. When compared with 166 conventional