A case of intrahepatic clear cell cholangiocarcinoma

Figure 1 Findings of contrast enhanced computed tomography (CT) of the abdomen (arrows indicate the tumor). A: Plain CT shows a well-circumscribed mass in the posterosuperior S7 of the right lobe, measuring approximately 2 cm in diameter, with no calcification or fatty component; B: Enhanced CT of the arterial phase shows that it is well-enhanced; C: Enhanced CT of the equilibrium phase shows a washed-out image.

Figure 2 Findings of magnetic resonance imaging (arrows indicate the tumor). A: The T2-weighted image shows a hyperintense tumor; B: The inverse video of the diffusion-weighted image shows a markedly hyperintense signal; C: In-phase T1-weighted image shows a hypointense signal; D: Opposed-phase T1-weighted image shows no signal intensity reduction compared with Figure 2C.

Figure 3 Tumor images. A: Photograph of the cut surface of the tumor fixed in formalin shows a yellowish-white, solid tumor, measuring 1.5 cm × 2.2 cm. Although the tumor margin is clear, there is no fibrous capsule. Neither bleeding nor blood vessels inside the tumor are observed. The outline margin with the surrounding liver is irregular; B: Scanning image. The tumor consists of clear cells. The margin is clear. The area surrounded by the black line is the poorly differentiated area.

Figure 4 Pathological findings (hematoxylin-eosin). A: Clear tumor cells proliferate in a tubular shape. The pushing margin is irregular (× 40); B: Area of well-differentiated duct formation. The tumor cells have copious clear cytoplasm (× 200); C: The poorly differentiated area shows solid proliferation (× 200).

Figure 5 Particular stains (× 400). A: The tumor cells show a weak reaction for periodic acid Schiff (PAS) stain; B: PAS stain is slightly digested by diastase treatment; C: Mucicarmine is negative; D: Alcian blue is negative.

Figure 6 Immunohistochemical staining (× 200). A: Cytokeratin (CK) 7 is positive; B: CK19 is positive; C: Vimentin is positive; D: CD56 is focally positive; E: Epithelial membrane antigen (EMA) is positive at the membrane of the luminal side.