Fig. 6

Histopathological findings. Histopathological findings showed a white nodule localized in the bile duct (a), papillary adenoma, and poorly differentiated adenocarcinoma (b). Transitional zone from adenoma to well-differentiated adenocarcinoma (c) and well-differentiated adenocarcinoma to poorly differentiated adenocarcinoma (d). There were BilIN around the tumor in the bile duct (e), but the liver tissue was normal (f). b × 40 magnification, c–f × 100 magnification