Histological study of gallbladder and bile duct epithelia in patients with anomalous arrangement of the pancreaticobiliary ductal system: comparison between those with and without a dilated common bile duct

We histologically evaluated the epithelia of the gallbladder (GB) and bile duct (BD) in patients with anomalous arrangement of the pancreaticobiliary ductal system (AAPB), with regard to the shape of the common BD (CBD). The GB and BD were studied histologically using surgical materials from 44 patients with AAPB: 27 with a dilated CBD (D-type) and 17 with a nondilated CBD (N-type). GB cancer and BD cancer were found in 11.1% and 3.7% of D-type and 17.6% and 0% of N-type respectively. Hyperplastic epithelium and atypical epithelium of the GB were frequently seen in both D-type (46%, 46%) and N-type (82%, 70%), while such epithelia of the BD were only seen in D-type (10%, 35%). The Ki67 labeling index of the nonneoplastic epithelium of the GB was high in both D-type (13.0%) and N-type (9.7%), though that of the BD was high in D-type (12.5%) but low in N-type (1.8%). The prevalences of pyloric gland metaplasia, intestinal metaplasia, and p53 protein overexpression of the nonneoplastic epithelium did not show any significant differences between D-type and N-type. It is suggested that the BD epithelium of N-type probably has a lower potential for developing malignancy than that of D-type, while the GB epithelia of both D-type and N-type have a high potential for developing malignancy. This might support the selection of simple cholecystectomy as the treatment of choice in AAPB patients of N-type, although further investigation of the BD epithelium is required in a larger number of such patients.