acinar cell carcinoma ( acc ) of the pancreas is a rare tumor that is estimated to account for 12% of all pancreatic exocrine tumors [ 1 , 2 ] . because of the lack of clinical experience with acc , its pathophysiology is not well understood . according to previous reports
, acc generally shows expansive growth without invasion into the plexus , portal vein , bile duct and pancreatic duct [ 3 , 4 ] . to our knowledge
, no previous reports have described hepatic metastasis from acc primarily in the form of a tumor thrombus .
we encountered a very rare case of hepatic metastasis with an unusual clinical presentation : a bile duct tumor thrombus ( bdtt ) from pancreatic acc .
a 66-year - old woman had undergone total pancreatectomy due to pancreatic acc ( t3n0m0 , stage iia ) 7 years prior to clinical presentation .
computed tomography ( ct ) imaging showed a tumorous lesion measuring 7 cm in length and 1 cm in diameter and extending along the intrahepatic bile duct ( b6 ) . during ct imaging ,
the lesion showed mild enhancement in the early phase and modest washout in the late phase ( fig .
ct arteriography ( cta ) showed early enhancement , which corresponded to the tumorous lesion detected by ct(fig .
f - fluorodeoxyglucose positron emission tomography / ct ( fdg - pet / ct ) showed high fdg uptake within the corresponding area ( fig .
the tumor was primarily confined to the intrahepatic bile duct ( b6 ) without definitive mass formation in the hepatic parenchyma .
tumor markers , including cea , ca19 - 9 and dupan - ii , were all within normal limits .
since pathological evaluation of the fine needle biopsy specimen from the bdtt revealed histological features that were compatible with those of the patient 's acc resected 7 years before , the lesion was diagnosed as a hepatic metastasis primarily in the form of a bdtt originating from the prior acc .
we initiated chemoradiation therapy ( crt ) , consisting of a total radiation dose of 50 gy and the intravenous administration of gemcitabine ( 1,000 mg / m ) concurrently on days 1 , 8 , and 15 during each 4-week cycle .
although a modest effect was observed 13 weeks after the initiation of crt , with a decrease in blood flow and size of the bdtt ( fig .
2a ) , the lesion showed an increase in size 19 weeks after the initiation of crt ( fig .
thus , surgical resection , including subsegmentectomy ( s6 ) of the liver and complete removal of the bdtt , was performed .
pathological evaluation of the resected specimen confirmed a hepatic metastasis primarily consisting of a bdtt that originated from an acc of the pancreas ( intraductal polypoid growth variant ) .
the detailed pathological evaluation of the bdtt and the comparison of this tumor 's characteristics with those of the primary pancreatic lesion that was resected 7 years before are presented in a separate report .
although our experience is only anecdotal , the case reported here provides several novel observations in regard to the clinical features associated with pancreatic acc .
first , it underscores the need for a long - term follow - up for pancreatic acc cases , even after curative resection .
this case involved a liver metastasis that was detected more than 5 years postoperatively , which is unique as hepatic metastases normally occur within a relatively short period following resection of the primary lesion [ 7 , 8 ] .
second , aggressive surgical resection combined with crt for hepatic metastasis from pancreatic acc should be considered as a treatment option in selected cases .
however , the treatment strategy for metastatic or recurrent acc remains controversial even though various treatment options , including chemotherapy , crt and surgical resection , have been reported [ 7 , 8 , 10 , 11 , 12 ] .
reported a case of hepatic metastasis from acc that was successfully treated with an aggressive surgical approach .
the advantage of crt prior to surgical resection for hepatic metastasis from acc is unclear .
however , a preoperative crt strategy might be beneficial especially in marginally resectable cases because a partial response to crt was observed in the case presented here .
third , although multimodal approaches may be useful for selected acc cases [ 10 , 11 , 12 ] , careful repeated re - evaluations during the preoperative treatment period are necessary to improve the chances for a curative resection as demonstrated by our current case , in whom the bdtt showed regrowth after a partial response to crt
. further studies with a larger number of patients are required to fully understand the pathophysiology of acc and to evaluate the benefits of multimodal treatment strategies for recurrent acc .
 pancreatic acinar cell carcinoma ( acc ) is a rare tumor , and its pathophysiology has not been well understood . 
 treatment strategies for hepatic metastasis originating from acc remain controversial . 
 we report the case of a 66-year - old woman who had undergone total pancreatectomy from acc 7 years prior to clinical presentation . 
 contrast - enhanced computed tomography imaging revealed a tumorous lesion measuring 7 cm in length and 1 cm in diameter and extending along the intrahepatic bile duct ( b6 ) , which showed mild enhancement in the early phase and modest washout in the late phase . 
 this lesion was diagnosed as hepatic metastasis primarily in the form of a bile duct tumor thrombus originating from the prior acc by the pathological evaluation of the fine needle biopsy specimen . 
 the patient underwent preoperative gemcitabine - based chemoradiation therapy followed by subsequent surgical resection , which included subsegmentectomy ( s6 ) of the liver and complete removal of the bile duct tumor thrombus . 
 the patient has had no recurrence during the past 8 months since her last surgery . 
 multimodal treatment including preoperative chemoradiation therapy might be beneficial especially for marginally resectable cases of acc . 
Introduction
Case Report
Discussion
Disclosure Statement