Systematic Selective Sampling of Cholecystectomy Specimens Is Adequate to Detect Incidental Gallbladder Adenocarcinoma

Many gallbladder adenocarcinomas (ACs) are detected incidentally in routine cholecystectomy specimens, yet sampling practices vary when intestinal metaplasia (IM) or dysplasia are found via routine sampling. Our practice has been to submit 5 additional sections when IM is found, but cases with dysplasia are entirely submitted. We sought to determine an appropriate sampling protocol when encountering these findings. We retrospectively identified cholecystectomy specimens with these features over a 26-month period, yielding 48 of 4059 (1%) cases. Four pathologists independently classified the (2 longitudinal and 1 cystic duct margin) original sections into 1 of 3 categories (IM, low-grade dysplasia [LGD] or high-grade dysplasia [HGD]); initial findings were correlated with final diagnoses. Sixteen (33%) cases had additional findings upon further sampling, including LGD (n=10) or HGD (n=4) and AC (n=2). HGD always accompanied malignancy. We prospectively analyzed 39 of 3133 (1%) additional cholecystectomy specimens, initially submitting the same routine sections. We submitted 5 random sections from cases with IM. Cases with LGD were first examined with 1 additional section per centimeter. All remaining tissue was submitted in all of these cases and separately reviewed. Cases with HGD were entirely submitted as both test cases with HGD in initial sections ultimately showed carcinoma. This protocol detected all cases of HGD and AC. Patients with clear cystic duct margins did not experience neoplastic progression, even if dysplasia was present elsewhere. We conclude gallbladders with HGD should be entirely submitted, LGD may be representatively sampled, and routine sampling is adequate for IM.