Fig. 4.

(a) Microscopic findings of the tumor in the junction of the cystic duct. The atypical cells form irregular duct structures, and the tumor was diagnosed as a well-to-moderately differentiated adenocarcinoma (hematoxylin and eosin, magnification 20×). (b) Microscopic findings of the tumor in the distal bile duct. The tumor cells spread invasively with solid and trabecular formation. The tumor was diagnosed as a poorly differentiated adenocarcinoma (hematoxylin and eosin, magnification 20×). (c) Microscopic findings of transition zone between the tumor in the junction of the cystic duct and the tumor in the distal bile duct. There was no communication between the 2 cancers (A; the tumor in the junction of the cystic duct, B; the tumor in the distal bile duct) (hematoxylin and eosin, magnification 10×).