[705] Histology and Histopathology of Minor Papilla (Accessory Ampulla): An Analysis of 160 Cases with Emphasis on Features with Potential Impact on Daily Surgical Pathology Practice

Denizhan Ozdemir, Burcu Saka, Pelin Bagci, Nevra Dursun, Ipek Erbarut, Sudeshna Bandopadhyay, Leslie Ducato, Michelle Reid, Alton B Farris, Olca Basturk, Volkan Adsay. Emory University, Atlanta, GA; Wayne State University, Detroit, MI; Memorial Sloan-Kettering Cancer Center, New York, NY

Background: The histologic features and pathologic conditions of the minor papilla (MP) are poorly characterized. The literature is mostly based on limited data or autopsy material.
Design: MP from 160 pancreatoduodenectomy specimens was analyzed.
Results: MP was identified as a mucosal-covered polyp localized approximately 1.8 cm (1.3-2.5 cm) proximal and anterior to major papilla. The surface mucosa was composed of foveolar-type epithelium (prone to be mistaken as “peptic duodenitis” or heterotopias in biopsies) with scattered goblet cells, admixed with biliary type ducts, embedded in small intestinal mucosa in variable patterns. The submucosa comprised lobules of ductules with variable morphology, some showing small round ductular conglomerates lined by cuboidal cells characteristic of peribiliary glands, whereas some were elongated and lined by columnar mucinous pyloric-type cells. Often lobular, surrounded by muscular coat, the glandular units created an adenomyoma-like picture. Columnar thin dark cells with stratification resembling low-grade dysplasia were seen in 12 %. Neuroendocrine cells were commonly encountered and also formed micronests in the stroma resembling microcarcinoids, which was prominent in 10%. Pancreatic acinar tissue was seen in 48%, either well-preserved (31%) or atrophic (17%), 54% of which also contained islets of Langerhans. Rare paneth cells were identified in the ducts. PanIN type changes were seen in the ducts in 14 cases (11-PanIN1, 3-PanIN2); 8 occurred in patients with PDAC. In addition to secondary invasion by carcinoma (8 cases), which could colonize the ducts (4), MP ducts were also involved by pagetoid spread from remote carcinomas (4) and mimicking PanIN. The MP was also the primary site of a substantial pathology in 18 cases: Paraduodenal (groove) pancreatitis- 14, intraductal papillary mucinous neoplasm - 3, and invasive carcinoma -1.
Conclusions: MP forms a mucosal nodule that is prone to be mistaken for a neoplastic polyp endoscopically. The surface epithelium typically contains foveolar cells with the differential of heterotopia or peptic duodenitis. Neurondocrine cell micronodules are a part of MP histology. Often, the submucosal architecture is that of an adenomyoma. PanINs can be found in MP ducts, and pagetoid intramucosal spread from underlying carcinomas also occurs. A variety of pathologic conditions, especially paraduodenal pancreatitis, but also IPMNs and invasive carcinoma can arise from MP.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 107, Wednesday Afternoon


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