PMC5141378_01
The primary rectal adenocarcinoma. Macroscopically, an irregular, reddish, ulcerated
mass measuring 6 x 5 cm in size was found on the mucosal surface of the rectum (a,
arrow). The tumor was diagnosed as a well-differentiated adenocarcinoma (b,
hematoxylin and eosin, x 200).
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Histologically, the tumor was a well-differentiated adenocarcinoma with lymphovascular invasion (Figure 1a, b).
Preoperative computed tomography findings. Abdominal contrast-enhanced computed
tomography reveals distention of the superior branch of the bile duct of segment III
of the liver (B3; arrow in [a]) and a nodule in the same segment (arrow in [b]). A
slightly enhancing lesion extends along the inferior branch of B3 (arrowhead in
[b]).
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Abdominal contrast-enhanced computed tomography revealed distention of the superior branch of the bile duct in segment III of the liver (B3) (Figure 2a) as well as a nodule in the same segment (Figure 2b). A slightly enhancing lesion extended along the inferior branch of B3 (Figure 2b).
Preoperative magnetic resonance imaging findings. Abdominal magnetic resonance
imaging shows a tumor (indicated by the arrow) along the bile duct in the left lateral
segment, with a low-intensity signal on T1-weighted images (a), an isointense signal
with background liver parenchyma on T2-weighted images (b), and a high-intensity
signal on diffusion weighted images (c).
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Abdominal magnetic resonance imaging revealed a tumor along the inferior branch of B3, with a low-intensity signal on T1-weighted images (Figure 3a) and an isointense signal with background liver parenchyma on T2-weighted images (Figure 3b). B3 exhibited a high-intensity signal (Figure 3c). Based on these findings, the differential diagnoses were metastatic liver tumor from rectal carcinoma and IHCC.
Macroscopic findings of the liver tumor. Macroscopically, a whitish nodule measuring
1.5 x 1.0 cm is observed in segment III adjacent to the inferior surface of the liver
(arrow). The figure shows that the tumor involves the inferior branch of the bile duct
in segment III and predominantly extends along it (arrowheads). The boxed area is
highlighted in Figure 5.
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Macroscopically, a whitish nodule, measuring 1.5 x 1.0 cm, was found in the parenchyma of segment III adjacent to the inferior surface of the liver (Figure 4).
Histological findings of the liver tumor. The histological appearance of the area
highlighted by the solid box in Figure 4 is
shown. On gross appearance (a), the tumor presented with intrabiliary growth.
Histological examination shows an adenocarcinoma with intrabiliary growth replacing
the bile duct epithelium (b, c). The boxes with solid and dashed borders in (a) are
highlighted in panels (b) and (c), respectively. Asterisks in (a) and (c) indicate
necrotic tissue. The adjacent bile duct shows no cellular atypia (b, c). High-power
magnification shows that the cells of the liver tumor contained pencil-like and
hyperchromatic nuclei (d). Insets in (b) and (c) are digital enlargements of the
highlighted areas in each respective figure. Hematoxylin and eosin: (a) loupe view;
(b) x 20; (c) x 20; (d) x 100.
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Histological examination revealed that an adenocarcinoma showed predominantly intraductal papillary growth replacing the bile duct epithelium (Figure 5a, b, c). The tumor cells showed abrupt transition to the adjacent bile duct, which in turn showed no cellular atypia (Figure 5b, c). The tumor cells of the liver contained pencil-like hyperchromatic nuclei (Figure 5d).
Immunohistochemical analysis of the liver tumor. The tumor regions from panel (a)
were stained with various antibodies. The tumor cells are negative for cytokeratin
(CK) 7 expression (arrow in [b]), while the neighboring biliary epithelial cells show
positive CK7 staining (arrowhead in [b]) (b). Both the tumor cells (arrow in [c]) and
biliary epithelial cells (arrowhead in [c]) are negative for CK20 (c). The tumor cells
(arrow in [d]) are negative for carbohydrate antigen 19-9 (CA19-9) while the biliary
epithelial cells (arrowhead in [d]) are positive for CA19-9 (d). (a) hematoxylin and
eosin; (b) CK7; (c) CK20; (d) CA19-9 x100.
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CK20 on immunohistochemical analysis (Figure 6b, c), whereas the normal biliary epithelium was positive for CK7 and negative for CK20 (Figure 6b, c). CA19-9 was absent in the tumor cells, but present in the biliary epithelial cells (Figure 6d).