Background and study aims: Choledochocele has a potential for carcinogenesis, but no report has described malignant changes of the choledochocele in relation to pancreaticobiliary reflux because its anatomic form does not fit the criteria of pancreaticobiliary malunion (PBM). The aims of this study were to analyze the amylase level in bile in patients with choledochocele and to clarify whether the presence of a choledochocele predisposed to carcinoma. Patients and methods: Records of 2826 patients who had undergone endoscopic retrograde cholangiopancreatography between 1995 and 1999 were reviewed for the presence of choledochocele and/or periampullary carcinoma. As an evidence of pancreaticobiliary reflux, amylase activity was examined in common duct bile obtained at surgery or by endoscopy. The prevalence of periampullary carcinoma was compared between patients with and without choledochocele. Results: A total of 11 patients were diagnosed as having a choledochocele. The amylase level in bile was higher in patients with choledochocele (120 922 ± 62 269 IU/I; n = 4) than in previously examined patients with functioning gallbladders (15 ± 24 IU/I; n = 10, P = 0.005). The prevalence of periampullary carcinoma in patients with choledochocele (27%, 3/11) was significantly higher than that in those without choledochocele (0.9%, 26/2815; P < 0.0002). Conclusion: The bile analysis of the present study presents one possible explanation for the predisposition to carcinoma in choledochocele as bile containing amylase may stagnate in the choledochocele and then carcinoma may develop in the inner epithelium of the choledochocele by the same mechanism as that leading to carcinogenesis in patients with PBM.
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