Pancreatobiliary and ampulla of Vater
adenocarcinomas frequently metastasize to regional lymph nodes, liver, or lung and are difficult to diagnose because they lack specific immunohistochemical markers. We studied the expression of
cytokeratin 7 (CK7),
cytokeratin 17 (CK17),
cytokeratin 20 (CK20), CDX2,
mucin 1 (
MUC1), mucin 2 (MUC2), and
mucin 5AC (MUC5AC) in 46 cases of
pancreatic ductal carcinoma, 18 ampulla of Vater
adenocarcinomas, and 24
intrahepatic cholangiocarcinomas. The expression of MUC1 and CK17 was restricted to
pancreatic ductal carcinoma (41 of 46, 89%; 38 of 46, 83%, respectively), the ampullary
carcinoma of pancreatobiliary origin (6 of 6, 100%; 5 of 6, 83%, respectively), and
intrahepatic cholangiocarcinoma (20 of 24, 83%; 17 of 24, 71%, respectively). More than 50% of cases of pancreatobiliary
adenocarcinomas showed diffuse cytoplasmic CK17 positivity. In contrast, less than 5% cases (8 of 184) of extra-pancreatobiliary nonmucinous
adenocarcinomas expressed CK17, and only 3 of them showed diffuse CK17 positivity. The expression of MUC2 and CDX2 was restricted to the intestinal, mucinous, and signet-ring cell-type
adenocarcinomas of duodenal papillary origin (9 of 11, 82%; 11 of 11, 100%, respectively). MUC2 was rarely expressed in
pancreatic ductal carcinoma (1 of 46, 2%) and was negative in the ampullary
carcinoma of pancreatobiliary origin and in
intrahepatic cholangiocarcinoma. A heterogeneous CDX2 staining pattern was seen in 1 of 6 cases of the ampullary
carcinoma of pancreatobiliary origin (17%), 5 of 24
intrahepatic cholangiocarcinomas (21%), and 10 of 46 (22%)
pancreatic ductal carcinomas. In contrast, all 11 cases of the intestinal, mucinous, and signet-ring cell-type
adenocarcinomas of duodenal papillary origin showed homogeneous CDX2 nuclear positivity. We concluded that CK17 is a useful marker in separating pancreatobiliary
adenocarcinomas from extra-pancreatobiliary nonmucinous
adenocarcinomas, including
adenocarcinomas from the colon, breast, gynecologic organs, stomach, lung, prostate, thyroid, kidney, and adrenal gland, and
malignant mesothelioma. MUC1+/CK17+ can be used as positive markers for
pancreatic ductal carcinomas, the ampullary
carcinoma of pancreatobiliary origin, and
cholangiocarcinomas with positive predictive values of 76%, 83%, and 58%, respectively. MUC2+/CDX2+ can be used as positive markers for the intestinal-type
adenocarcinoma of duodenal papillary origin with a positive predictive value of 82%.