Krasinskas, Alyssa, Mittal, Pardeep, Ito, Tetsuya, Horigome, Naoto, Okaniwa, Shinji, Muraki, Takashi, Koshiol, Jill, Sarmiento, Juan M., Memis, Bahar, Maithel, Shishir, Adsay, Volkan, Uehara, Takeshi, Freedman, Alexa, Hisa, Takeshi, Hasebe, Osamu, Reid, Michelle D.
Pancreaticobiliary maljunction (PBM) is the anomalous union of the main pancreatic duct and common bile duct outside the Oddi-sphincter, allowing the reflux of pancreatic juice to the gallbladder. There is only limited awareness and understanding of the pathologic correlates of this condition, mostly from Japan; this entity is largely unrecognized in the West. In this study, 76 gallbladders from patients with PBM (64 from Japan; 12 from the United States) were analyzed and contrasted with 66 from non-PBM patients. These were predominantly females (54 vs. 22), mean age, 53 (range: 14 to 81). Cholelithiasis was uncommon (16% vs. 80% in non-PBM, P<0.01) whereas cholesterolosis was more common (49% vs. 29%, P=0.02) suggesting an altered chemical milieu. There was a distinctive diffuse mucosal hyperplasia (82% vs. 42%, P<0.01) with markedly elongated folds (mean: 1.1 vs. 0.7 mm, P<0.01) composed of compact villoglandular proliferation, often showing broad-based pushing into muscle, accompanied by prominent and more complex Rokitansky-Aschoff sinus formation (2.0 vs. 1.0/cm, P<0.01) at the base. At the tips, this villiform hyperplasia displayed frequent horizontal bridging of the folds (68% vs. 47%, P=0.01), bulbous dilatation (52% vs. 21%, P<0.01) as well as deposition of a peculiar amyloid-like hyaline material (56% vs. 15%, P<0.01). Despite paucity of inflammation and gallstones, findings attributed to mucosal injury were common including: pyloric gland metaplasia (70% vs. 48%, P=0.01) and intestinal metaplasia (24% vs. 6%, P<0.01). Invasive gallbladder carcinoma was present in 22 (29%) of the cases with 6 of these (27%) arising in association with intracholecystic papillary tubular neoplasm. Five cases had bile duct carcinoma at the time of cholecystectomy and 1 developed it 4 years after. In conclusion, gallbladders with patients with PBM display a distinctive pattern of mucosal hyperplasia with distinguishing features, which in constellation render it a microscopically diagnosable specific entity. We propose to refer to this entity as “reflux-associated cholecystopathy.” Recognition of the pathologic characteristics of this entity is important so that investigation for, as well as treatment and prevention of, PBM-associated complications (biliary tract cancers and pancreatitis) can be instituted. This group also offers a distinct model of carcinogenesis (chemical rather than inflammatory) in the gallbladder for cancer researchers to scrutinize.