Fig. 6

Macroscopic and histopathologic image of the specimen. 6A-1 Sagittal slice of the specimen at the level of the right hepatic hilum. A whitish solid and poor circumscribed tumor involved the right hepatic hilum (arrow) and extended along the posterior glissonean pedicle (arrowheads). The white line indicates the surgical cut margin of the bile duct. 6A-2 Tumor involved the posterior glissonean pedicle and surrounding hepatic parenchyma (arrowheads). H.E. staining. Scale bar = 500 µm. 6A-3 Tumor was composed of moderately differentiated tubular adenocarcinoma with a desmoplastic reaction. Perineural and lymphovascular invasion were observed. H.E. staining. Magnification of × 400. 6B-1 Sagittal slice at the middle of the segment 6. Grossly, the segment 6 bile ducts were cystically dilated, and no gross intraductal tumor was identified. 6B-2 Micropapillary or sessile proliferations of columnar epithelial cells were diffusely observed. The length of intraepithelial extension was approximately 120 mm. H.E. staining. Scale bar = 5 µm. 6B-3 Neoplastic lesions exhibited marked nuclear atypia, loss of nuclear polarity, and presence of mitoses, leading to a diagnosis of high-grade BilIN. H.E. staining. Magnification of × 400. 6C-1 At the peripheral slice of the segment 6. Similarly, diffuse bile duct dilatation was observed at the peripheral side of segment 6. 6C-2 Minimally invasive foci of atypical epithelial cells were observed in the peripheral hepatic parenchyma of segment 6 (arrowheads). The maximum size of invasion was approximately 2.1 mm in diameter. H.E. staining. Scale bar = 5 µm. 6C-3 Moderately differentiated tubular adenocarcinomas with desmoplastic reactions were observed. H.E. staining. Magnification of × 400.