Introduction: On occasional cholecystectomies, pathologists encounter incidental dysplasia in the gallbladder mucosa in the sections submitted per protocol for histologic examination. If dysplasia is identified, additional sections are taken and/or the gallbladder is entirely submitted to rule out underlying adenocarcinoma. The aim of our study was to assess the incidence of subsequent identification of invasive adenocarcinoma on additional sections, after an incidentally detected dysplasia was noted on a routine cholecystectomy section. We also aimed to study the significance of the incidental detection of dysplasia and adenocarcinoma, as well as showing the association of gallbladder dysplasia to synchronous or metachronous dysplasia/neoplasia in the biliary tract.
Material and methods: Our study was approved by the Institutional Review Board. We retrospectively identified 41 consecutive cases of routine cholecystectomies from 1991 to 2017, which had no clinical suspicion of neoplasia, and did not have any identifiable mass lesion, but on histopathologic analysis, had neoplasia (adenocarcinoma in 4 cases, and dysplasia in 37 cases). The pathologies of all cases were reviewed, and the diagnosis and grade of dysplasia were confirmed. The clinical information was obtained from the electronic medical records.
Results: Of the 37 cases with dysplasia, 10 (27%) had high-grade dysplasia (HGD) and the remaining showed low-grade dysplasia (LGD). All 4 cases of adenocarcinoma had some gross abnormalities (such as porcelain gallbladder, or ruptured, thickened, and roughened walls, or a granular mucosa). In contrast, none of the 37 cases with dysplasia had any gross abnormality. In 24 (of 37) cases of dysplasia, additional sections were submitted (median 8; ranging from 2 to 29), and in 11 cases, the gallbladder was entirely submitted. None of these cases showed any additional pathologic finding on the extra sections. Interestingly, 7 cases with dysplasia (18.9%; 6 LGD and 1 HGD) were associated with a concomitant pancreatobiliary malignancy. For the remaining 30 cases, follow-up information was available in 16 cases (53.3%) with a mean follow-up of 76.5 months (ranging from 12 to 204 months). None of these showed any subsequent development of pancreatobiliary neoplasms.
Conclusion: Incidentally detected gallbladder dysplasia in a cholecystectomy specimen, without any gross abnormality, has almost no risk of a hidden invasive carcinoma. Although cholecystectomy is sufficient treatment for gallbladder dysplasia, in our study cohort, 18.9% of cases with incidental dysplasia in gallbladder had an associated pancreatobiliary carcinoma, which supports the hypothesis of multifocal neoplastic potential in the pancreatobiliary tree (also known as field effect). Although follow-up on 16 cases shows no subsequent development of any other pancreatobiliary neoplasm, this number is probably not enough to rule out a serial imaging follow-up of patients who have reported dysplasia in their gallbladder, to assess for subsequent development of neoplasia elsewhere in the pancreaticobiliary tree.
Keywords: Follow-up; Gallbladder; Hepatobiliary malignancies; Incidental dysplasia.