liver metastases from colorectal carcinoma ( crc ) commonly form nodular lesions in the liver 
 parenchyma .
however , there 
 have been reports of unusual cases of metastatic liver tumors from crc that predominantly 
 extend along the intrahepatic bile duct .
such unusual tumors generally mimic intrahepatic 
 cholangiocarcinoma ( ihcc ) clinically , radiographically , and pathologically .
importantly , it remains unclear whether anatomical or partial 
 hepatectomy is more suitable to treat such tumors .
herein , we report a case of liver 
 metastasis from crc presenting as an intrabiliary growth , and discuss the 
 clinicopathological considerations that inform selection of the surgical procedure for such 
 tumors .
the patient was a 62-year - old japanese man who had undergone low anterior resection for 
 rectal carcinoma 9 years earlier .
histologically , the tumor was a well - differentiated adenocarcinoma with 
 lymphovascular invasion ( figure 1a , bfigure 1the primary rectal adenocarcinoma .
macroscopically , an irregular , reddish , ulcerated 
 mass measuring 6  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 ,  200 ) . ) .
three years and 2 months after the surgery , a metastatic tumor was found in liver 
 segment vi .
the patient chose radiofrequency ablation therapy ( rfa ) over surgery . during a 
 post - rfa follow - up period of 6 years and 1 month , his serum carcinoembryonic antigen ( cea ) 
 and carbohydrate antigen 19 - 9 ( ca19 - 9 ) levels remained within the normal ranges .
however , 1 
 week before admission , serum cea and ca19 - 9 levels were elevated to 6.8 ng / dl ( normal range , 
 < 5.0 ng / dl ) and 40.3 u / ml ( normal range , < 37.0 u / ml ) , respectively . the primary rectal adenocarcinoma .
macroscopically , an irregular , reddish , ulcerated 
 mass measuring 6  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 ,  200 ) .
on admission to our hospital , the patient exhibited no abnormalities on physical 
 examination .
abdominal contrast - enhanced computed tomography revealed distention of the superior branch 
 of the bile duct in segment iii of the liver ( b3 ) ( figure 
 2afigure 2preoperative 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 ] ) . ) as well as a nodule in the same segment ( figure 
 2b ) .
a slightly enhancing lesion extended along the inferior branch of b3 ( figure 2b ) .
abdominal magnetic resonance imaging 
 revealed a tumor along the inferior branch of b3 , with a low - intensity signal on t1-weighted 
 images ( figure 3afigure 3preoperative 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 ) . ) and an isointense signal with background liver parenchyma on t2-weighted images 
 ( figure 3b ) . on diffusion - weighted images ,
the 
 lesion in the inferior branch of b3 exhibited a high - intensity signal ( figure 3c ) .
based on these findings , the differential diagnoses were 
 metastatic liver tumor from rectal carcinoma and ihcc . hence , we performed a left 
 hepatectomy with dissection of the lymph nodes in the hepatoduodenal ligament .
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 ] ) .
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 ) .
macroscopically , a whitish nodule , measuring 1.5  1.0 cm , was found in the parenchyma of 
 segment iii adjacent to the inferior surface of the liver ( figure 4figure 4macroscopic findings of the liver tumor .
macroscopically , a whitish nodule measuring 
 1.5  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 superior 
 branch of b3 and the bile duct in segment ii were preserved .
macroscopically , a whitish nodule measuring 
 1.5  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 ) .
histological examination revealed that an adenocarcinoma showed predominantly intraductal 
 papillary growth replacing the bile duct epithelium ( figure 5a , b , cfigure 5histological 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 .
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 )  20 ; ( c )  20 ; ( d )  100 . ) .
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 ) .
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 - 9 100 . ) were negative for cytokeratin ( ck ) 7 and 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 ) .
because both the original and 
 metastatic tumors demonstrated strikingly similar histological appearances , the tumor was 
 diagnosed as a liver metastasis from rectal carcinoma .
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 .
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 )  20 ; ( c )  20 ; ( d )  100 .
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 - 9 100 .
he has not exhibited any signs of recurrence in the liver or any other organ , 
 and is functioning well 3 years after the most recent surgery .
in the present case , a metastatic tumor from crc involved the inferior branch of b3 and 
 extended predominantly along this branch , with an intraductal papillary growth pattern . 

comparison between computed tomography images obtained 6 months before admission and those 
 obtained on admission showed the growth of the tumor ( figure 7a , bfigure 7comparison between the computed tomography images obtained 6 months before ( a ) and on 
 admission ( b ) .
six months before admission ( a ) , a slightly low attenuated nodule 
 measuring 1.5  1.0 cm in diameter was found close to the inferior surface of the 
 liver ( arrow in [ a ] , far right panel ) . on admission ( b ) , the nodule ( asterisk in [ b ] , 
 far right panel ) extended along the inferior branch of the bile duct in segment iii 
 ( b3 ) ( arrowheads in [ b ] , center and right panels ) .
owing to a tumor embolism in the 
 bifurcation of b3 , the superior branch was enlarged on admission ( box in [ b ] , left 
 panel ) .
neither enlargement of the superior branch of b3 nor tumor extension along the 
 inferior branch of b3 was observed 6 months before admission ( [ a ] , left , center , and 
 right ) . ) . on images obtained 6 months before admission , a nodule with a slightly low 
 attenuation , measuring 1.5  1.0 cm in diameter , was retrospectively discovered close to the 
 inferior surface of the liver ( figure 7a , right ) . 

neither enlargement of the superior branch of b3 nor tumor extension along the inferior 
 branch of b3 was observed 6 months prior to admission ( figure 7a ; left , center , and right ) . at the time of admission ,
this nodule had 
 already involved the inferior branch of b3 ( figure 
 7b ) .
owing to a tumor embolism in the bifurcation of b3 , the superior branch of b3 
 was enlarged on admission ( figure 7b ) .
the 
 increased tumor volume and bile duct obstruction may explain the slight elevation of the 
 serum cea and ca19 - 9 levels , respectively .
comparison between the computed tomography images obtained 6 months before ( a ) and on 
 admission ( b ) .
six months before admission ( a ) , a slightly low attenuated nodule 
 measuring 1.5  1.0 cm in diameter was found close to the inferior surface of the 
 liver ( arrow in [ a ] , far right panel ) . on admission ( b ) , the nodule ( asterisk in [ b ] , 
 far right panel ) extended along the inferior branch of the bile duct in segment iii 
 ( b3 ) ( arrowheads in [ b ] , center and right panels ) . owing to a tumor embolism in the 
 bifurcation of b3 ,
the superior branch was enlarged on admission ( box in [ b ] , left 
 panel ) .
neither enlargement of the superior branch of b3 nor tumor extension along the 
 inferior branch of b3 was observed 6 months before admission ( [ a ] , left , center , and 
 right ) .
liver metastases from crc occasionally involve the bile duct and show intraductal papillary 
 growth . according to a study by okano et al .
similarly , kubo et al . reported that 10.6% 
 ( 23/217 ) of liver metastases from crc presented with macroscopic intrabiliary 
 growth . a report from 
 jannelyn et al . on liver metastasis from crc concluded that 3.6% ( 41/1144 ) 
 and 10.6% ( 18/170 ) of retrospectively and prospectively analyzed cases , respectively , 
 presented with intrabiliary growth .
liver metastasis from crc with intrabiliary growth is associated with a better prognosis 
 than other forms of liver metastases .
reported that patients 
 with macroscopic bile duct invasion had a better 5-year survival rate ( 80% ) than those with 
 microscopic bile duct invasion ( 48% ) or no bile duct invasion ( 57% ) .
moreover , kubo et al . reported a significant 
 difference between patients with and without macroscopic intrabiliary extension in terms of 
 the interval between initial colectomy and hepatectomy ( 37.4  25.4 vs. 6.1  7.2 months , 
 respectively ) .
these 
 different outcomes may be explained by the fact that most tumors with intrabiliary growth 
 are well - differentiated adenocarcinomas .
this feature is characteristic of less aggressive tumors and 
 results in tumor colonization of the bile duct ; the normal biliary epithelium is replaced 
 with tumor cells , which grow along an intact basement membrane without penetrating 
 it .
the clinical course of 
 the patient presented here was consistent with that of a less aggressive tumor ; he had a 
 well - differentiated adenocarcinoma with intrabiliary extension and has survived for 3 years 
 after the hepatic surgery , for 9 years after rfa , and for 12 years after the primary surgery 
 of the rectum .
preoperative differentiation between liver metastasis from crc with intrabiliary growth and 
 ihcc is difficult .
there are no clinical symptoms that are highly characteristic of liver 
 metastasis from crc with intrabiliary growth .
while elevated cea and serum alkaline phosphatase levels are 
 common findings on laboratory tests , 
 , these markers can 
 also be elevated in ihcc patients , 
 .
the computed 
 tomography findings of liver metastasis from crc with intrabiliary growth are usually 
 nonspecific , although a thickened portal tract , intrahepatic bile duct dilatation , and a 
 wedge - shaped area with contrast enhancement are characteristic features of this type of 
 tumor . on the other 
 hand
importantly , this case provides evidence for the superiority of anatomical hepatectomy over 
 partial hepatectomy for metastatic liver tumors with intrabiliary growth arising from rectal 
 adenocarcinomas .
when liver metastases from crc form nodular lesions in the liver 
 parenchyma , partial hepatectomy may be a sufficient treatment ; however , when the tumor shows intrabiliary 
 spreading , as seen in the present case , partial hepatectomy alone may not completely excise 
 the tumor because of the extension along the bile ducts .
although there is no consensus regarding the most 
 appropriate procedure for such patients , anatomical hepatectomy tends to be preferred over 
 regional liver resection , 
 .
this is primarily to guard against the possibility of 
 residual tumor cells on the cut margin of the bile duct , 
 .
moreover , anatomical hepatectomy is the logical 
 choice because of the aforementioned difficulty in preoperatively differentiating between a 
 liver metastasis with intrabiliary growth arising from crc and ihcc . in the present case
, we 
 performed a left hepatectomy with sufficient margins in the bile duct that resulted in good 
 postoperative outcome ; the patient has survived for a relatively long period .
pathological discrimination between liver metastasis from crc and ihcc should be performed 
 carefully , based on both conventional histological examination using hematoxylin and eosin 
 staining and immunohistochemical staining with antibodies against ck7 and ck20 .
this 
 procedure is particularly important to determine the need for , and the selection of , 
 chemotherapy .
metastatic liver tumors from crc 
 with macroscopic intrabiliary growth show a histologically abrupt transition from the 
 adjacent bile duct epithelium to tumor tissue : cellular atypia is absent in the normal bile 
 duct epithelial cells . on 
 immunohistochemical analysis , a typical ck7/ck20 + expression pattern
9% 
 ( 18/206 ) of metastatic liver tumors from crc were negative for both ck7 and ck20 
 expression .
similarly , 
 sasaki et al . reported that 16% ( 4/25 ) of liver metastases from crc were 
 ck7/ck20 , whereas 
 rullier et al .
reported that no ck7/ck20 cholangiocarcinomas were found 
 among their cases ( 0/29 ) . in 
 the present case ,
the liver tumor showed a histological appearance similar to that of the 
 primary tumor , as well as an abrupt change from the normal bile duct epithelium to the 
 adenocarcinoma .
however , intrahepatic recurrence of the segment vi metastatic lesion treated with rfa 6 
 years before admission can not be completely ruled out .
intrahepatic recurrences after 
 treatment of metastatic liver tumors from crc show diverse patterns , including local 
 recurrence , multiple hepatic nodules , and intrahepatic distant metastases .
therefore , it is possible that 
 ours is a rare case of intrahepatic recurrence . in conclusion ,
we report an unusual case of liver metastasis from rectal adenocarcinoma 
 that presented with intrabiliary growth ( figure 
 8figure 8schematic representation of the tumor extension in the present case .
the metastatic 
 nodule formed in segment iii of the peripheral liver in , and involved the inferior 
 branch of the bile duct in segment iii , resulting in distention of the superior branch 
 of the bile duct in segment iii .
abbreviations : chd , common hepatic duct ; rhd , right hepatic duct ; b2 , bile duct in 
 segment ii ; b3 , bile duct in segment iii ; b3a , superior branch of b3 ; b3b , inferior 
 branch of b3 . ) . during follow - up
, physicians should consider the possibility of liver metastasis 
 with intrabiliary growth for patients with a history of crc .
moreover , our patient s long 
 survival time suggests that anatomical hepatectomy is a more effective treatment than 
 partial hepatectomy for metastatic liver tumors from crc with intrabiliary growth .
the metastatic 
 nodule formed in segment iii of the peripheral liver in , and involved the inferior 
 branch of the bile duct in segment iii , resulting in distention of the superior branch 
 of the bile duct in segment iii .
abbreviations : chd , common hepatic duct ; rhd , right hepatic duct ; b2 , bile duct in 
 segment ii ; b3 , bile duct in segment iii ; b3a , superior branch of b3 ; b3b , inferior 
 branch of b3 .
 liver metastases from colorectal carcinoma commonly form nodular lesions in the liver 
 parenchyma . 
 we report a case of liver metastasis from rectal adenocarcinoma that extended 
 predominantly into the bile duct . 
 a 62-year - old japanese man underwent low anterior 
 resection for rectal adenocarcinoma 9 years ago . 
 approximately 3 years later , he underwent 
 radiofrequency ablation therapy for a metastatic liver tumor . 
 nine years after surgery , a 
 tumor in liver segment iii exhibiting intrabiliary extension was discovered ; it was 
 unclear if this was a metastatic liver tumor or intrahepatic cholangiocarcinoma . 
 
 accordingly , we performed a left hepatectomy with lymph node dissection . 
 the tumor was 
 negative for cytokeratins 7 and 20 , and was histologically similar to the primary rectal 
 adenocarcinoma ; it was diagnosed as rectal carcinoma metastasis . 
 the patient has survived 
 for 3 years after the hepatic surgery , for 9 years after radiofrequency ablation therapy , 
 and for 12 years after the primary surgery . 
 this case shows that liver metastasis from 
 colorectal carcinoma can present as a predominantly intrabiliary growth that mimics 
 intrahepatic cholangiocarcinoma on imaging . 
 moreover , our case provides evidence for the 
 superiority of anatomical hepatectomy over partial hepatectomy for metastatic liver tumors 
 with intrabiliary growth arising from rectal adenocarcinomas . 
Introduction
Case Report
Discussion