although it comprises only 10 - 15% of all hepatobiliary neoplasms , its incidence is increasing.1 frequent metastatic sites of biliary cancer are the liver , peritoneum , intra - abdominal lymph nodes , and lungs.2 here , we describe a very rare case in which metastatic cholangiocarcinoma of the stomach was mistaken for primary gastric cancer in a patient who underwent whipple 's operation .
however , histopathologic and immunohistochemical findings suggested that the gastric tumor was a metastatic adenocarcinoma originated from a distal cholangiocarcinoma .
a 67-year - old woman presented with a 4-month history of abdominal pain after meals .
laboratory findings was as follows : aspartate aminotransferase 141 iu / l ( normal ; 10 - 40
iu / l ) and total bilirubin 0.9 mg / dl ( 0.2 - 1.0 mg / dl ) .
computed tomography showed a malignant tumor of the common bile duct ( cbd ) , located just above the intrapancreatic segment , with consequent dilatation of the proximal biliary tree including the gall bladder ( fig .
1 ) . the periportal , common hepatic , and portocaval lymph nodes were enlarged .
endoscopy revealed a 2-cm , flat , elevated lesion with convergence of the surrounding folds , situated at the gastric angle ( fig .
based on the biopsy results , an adenocarcinoma , thought to be an early gastric cancer , was diagnosed .
the patient underwent whipples 's operation . the surgical specimen consisted of a whitish mass , 2.11.3 cm in diameter , removed from the distal cbd and showing invasion of the pancreas and peripancreatic fat .
pathologic examination of the resected stomach demonstrated that the tumor was very clearly demarcated from the surrounding nontumorous gastric mucosa and submucosa , and also showed invading lymphovascular spaces .
in addition , the adenocarcinomatous tissue had infiltrated into the gastric mucosa and submucosa , while the gastric superficial mucosa was intact ( fig .
immunohistochemical stains showed that the tumor tissue was strongly positive for cytokeratin ( ck)-7 and weakly positive for ck-19 , while the surrounding gastric mucosa was negative for both cytokeratins ( fig .
according to a number of reports in the literature , metastasis to the stomach is a rare occurrence , with a reported incidence of less than 1% .
the main primary metastatic tumors are those of the breast ( 33% ) and lung ( 25% ) , and malignant melanoma ( 22%).3 in our patient , it was difficult to distinguish gastric metastasis of a cholangiocarcinoma from a primary gastric cancer on the basis of clinical , endoscopic , and radiologic features . thus , results obtained from complete histopathologic and immunohistochemical studies of gastric biopsies should be compared with the characteristic features of cancer of the cbd . the anatomic distribution of ck-7 and ck-19 is generally restricted to epithelia of primary sites and their neoplasm .
primary gastric cancer has the same staining pattern , because ck-7 and ck-19 expressions are reported to be positive in about 80% of stomach cancer cases .
however , both the normal gastric mucosa surrounding the tumor and the gastric carcinoma , if it originates from the stomach , are positive for ck-7 and ck-19.4,5 metastasis to the gastrointestinal tract initiates from the serosa and submucosa and progresses to cause intraluminal lesions , as occurred in this case.6 based on these considerations , we diagnosed metastatic gastric carcinoma from a distal cholangiocarcinoma .
another important immunohistochemical marker , cdx-2 is a very useful marker to distinguish stomach cancers from bile duct cancers , because cdx-2 expression is reported to be positive in 61% of stomach cancer cases but only in 13% of bile duct cancers , however cdx-2 was not performed in our study.7 until now , unusual metastastic sites from cholangiocarcinoma were reported to be the colon , adrenal gland , skull bone , epididymis , corneal limbus , meninges , ovary , skeletal musle , and skin.2,8 - 15 metastasis of a distal cholangiocarcinoma to the stomach has not been reported previously to our knowledge but , as in the above - mentioned sites , appears to be a rare site of metastasis of this tumor . in conclusion , a careful histopathologic and immunohistochemical review is very important in diagnostic differentiation of metastatic tumors from primary sites in this case .
 we report an unusual case of distal cholangiocarcinoma with gastric metastasis mimicking early gastric cancer . a 67-year - old woman presented with a 4-month history of abdominal pain after eating . 
 computed tomography showed a malignant tumor of the common bile duct located just above the intrapancreatic segment , and endoscopy revealed a 2-cm , flat , elevated lesion with convergence of the surrounding folds , situated at the gastric angle . 
 based on the endoscopic biopsy results , an adenocarcinoma , thought to be an early gastric cancer , was diagnosed . 
 the patient underwent whipples 's operation . 
 histopathological findings showed that the adenocarcinomatous tissue was clearly demarcated and infiltrated the gastric mucosa and submucosa , leaving the gastric superficial mucosa intact . 
 both tumors showed similar pathological features and were positive for cytokeratin ( ck)-19 and ck-7 . 
 these finding suggest distal cholangiocarcinoma with gastric metastasis . 