A case of intrahepatic clear cell cholangiocarcinoma

Abstract

Intrahepatic clear cell cholangiocarcinoma is very rare - only 8 cases have been reported. A 56-year-old Japanese man with chronic hepatitis B infection was diagnosed with a 2.2 cm hepatocellular carcinoma on imaging, and hepatic segmentectomy was performed. Histopathologically, the tumor cells had copious clear cytoplasm and formed glandular structures or solid nests. These pathological findings suggested the tumor was a clear cell variant of intrahepatic cholangiocarcinoma. Particular stains and radiological images suggested that the cause of the clear cell change had been glycogen, not mucin nor lipid. On immunohistochemical staining, cytokeratin (CK) 7 and CK19 were positive, whereas CK20 was negative. Vimentin was detected on the cell membranes, and CD56 was focally positive. The patient was given adjuvant chemotherapy and is currently free from the tumor 7 mo postoperatively. Careful follow-up with adequate postoperative supplementary chemotherapy is necessary because the characteristics of this type of tumor are unknown.

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.