Fig. 1

Microscopic examinations. a, b showing microscopic examination of the perihilar cholangiocarcinoma; c, d showing microscopic examination of the cholangiocarcinoma of the distal bile duct. a Adenocarcinoma arising from the bile duct in a large portal tract with stroma invasion. b On higher magnification it shows a moderately differentiated adenocarcinoma with a tubular, cribriform, and solid pattern of growth. c Examination of the papillary region showing pancreatic tissue in the upper left quadrant and infiltration into the papillary region by an adenocarcinoma. d On higher magnification it shows a poorly differentiated adenocarcinoma with tubular, cribriform, and solid growth pattern