Incidental metastases and lymphoma of the gallbladder–an analysis of ten rare cases identified from a large national database

Background: The aim was to identify and characterize rare malignancies of the gallbladder, incidentally found at cholecystectomy, and describe the diagnostic work-up, treatment and outcome. Methods: Data from cholecystectomies during 2007–2014 registered in the Swedish Register for Gallstone Surgery (GallRiks) were analyzed for incidental cancer. For completion of the pathology report, data were linked with the Swedish Registry for Cancer in the liver and biliary tract (SweLiv) and/or the Swedish Cancer Registry. Results: From 36,355 patients that underwent cholecystectomy on a benign indication 215 cases of incidental gallbladder cancer (IGBC) were identified. In total seven patients with metastases to the gallbladder from different primary tumors (breast cancer, malignant melanoma, gastric cancer, renal cell carcinoma, upper gastrointestinal cancer, colon cancer and pancreatic cancer) and three patients with lymphoma involvement of the gallbladder were found. Most patients were female with no difference between the groups (8/10 versus 171/215). The median age for the metastasis and lymphoma (MOL) group was equal to the IGBC group, 70 (64–72) years versus 70 (63–78) years. All patients in the MOL group underwent preoperative imaging with ultrasound or computed tomography, on which no metastases were identified. In only two patients a tumor was seen by the surgeon during the perioperative examination of the gallbladder. The median survival was 5.8 months for MOL patients and 23 months for IGBC patients. Conclusion: Metastases and lymphoma of the gallbladder are rare. Traditional imaging methods prior to cholecystectomy may miss gallbladder malignancies. A liberal approach of histopathological analysis of the gallbladder should be applied.