Fig. 4
From: Aggressive behavior of anaplastic undifferentiated carcinoma arising from the hilar bile duct
Tumor was mainly composed of pleomorphic atypical cells without ductal formation (A H/E × 200, B H/E × 400). Cytokeratin staining was weakly positive in these cells, while vimentin expression was strongly positive (C cytokeratin × 400, D vimentin × 400). E shows the transitional area from the normal biliary epithelium to a high-grade biliary intraepithelial neoplasm in the left intrahepatic duct (BilIN-3)