Large bile duct obstruction. a, Biliary cast syndrome in graft, OT 55, two years and two months after transplantation. The wall of the distended bile duct is fibrous, and the lumen is blocked by inspissated bile and debris. Hematoxylin and eosin, ×60. b, Biliary cast syndrome in graft, OT 43, 47 days after transplantation. A portal tract is greatly expanded and an intrahepatic bile duct is blocked by inspissated bile. Hematoxylin and eosin, ×50. c, Chronic large duct biliary obstruction. Enlarged fibrous portal tract with proliferated bile ductules containing bile casts. Hematoxylin and eosin, ×70.