Can the sampling method affect the detection of incidental gallbladder carcinoma? The importance of sampling in the detection of incidental gallbladder carcinoma

Gallbladder cancer (GBC) is the most common biliary tract carcinoma and is commonly diagnosed incidentally in cholecystectomies performed for gallstones. GBC are mostly unrecognizable macroscopically, and sampling is therefore import. This single center study aimed to find out the effect of sampling method on the identification rate of incidental GBC by comparing random sampling and longitudinal full-thickness slice sampling, which was developed in high-incidence areas. A hospital electronic database was searched for cholecystectomy specimens submitted to the pathology department between 01/2000 and 03/2016. Cases with a preoperative clinical and/or radiological suspicion of neoplasia and cases with a macroscopically identified mass were excluded from the study. Two groups were formed according to the sampling method: “random sampling” group (Group 1, n = 10,954) and “full-thickness slice sampling” group (Group 2, n = 5254). In the first group, random samples from the fundus, body and neck were submitted in gallbladders without grossly visible pathology. In the second group, a full-thickness slice sampling protocol was performed, wherein a longitudinal full-thickness slice, including fundus, corpus-neck and the cystic duct margin was submitted for each gallbladder. Statistical comparisons of GBC incidence and clinicopathologic features was performed. In group 1, GBC prevalence was 0.6 % and low grade dysplasia (LGD) was detected in 199 cases (1.8 %). In group 2, GBC prevalence was 1.5 %, LGD was detected in 166 cases (3.2 %). The GBC rate in Group 2 was significantly (p < 0.05) higher than Group 1. The two groups did not show any statistically significant differences in age, sex and presence of gallstones (p > 0.05). In conclusion, this is the largest study comparing two grossing methods in gallbladders without preoperative clinical and/or radiological suspicion of malignancy and macroscopically identified mass. This study demonstrates the importance of systematic and algorithmic sampling in the detection of GBC.