BRAF mutations have emerged as an important predictive biomarker for 
metastasized melanoma. Other types of cancer may also benefit from BRAF 
mutation-targeted therapies. In biliary tract cancer, reported BRAF mutation 
rates are highly controversial, ranging from 0 to 33% in adenocarcinoma of the 
gallbladder and 0 to 22% in cholangiocarcinoma. We here analyzed tissue 
microarrays of a large cohort of biliary tract cancer (n=377) including 159 
intrahepatic cholangiocarcinomas, 149 extrahepatic cholangiocarcinomas, and 69 
adenocarcinomas of the gallbladder for BRAF V600E mutation using a highly 
sensitive immunohistochemical screening approach implementing the BRAF V600E 
protein-specific antibody VE1. All VE1-positive cases as well as 42 VE1-negative 
cases were additionally analyzed by Sanger sequencing. In total, only 5 
VE1-positive cases were detected (5/377; 1%). BRAF V600E mutation was confirmed 
by direct sequencing in all cases. All 5 mutated cases were intrahepatic 
cholangiocarcinomas (5/159; 3%). None of the extrahepatic cholangiocarcinomas 
and adenocarcinomas of the gallbladder were VE1 positive. Apart from the subtype 
restriction of BRAF V600E mutation to intrahepatic cholangiocarcinoma and a 
female predominance (4 female, 1 male), no significant correlation with 
clinicopathological data and patient outcome was detected. In conclusion, we 
demonstrate that BRAF V600E mutation is a rare event in biliary tract cancer, 
accounting for only 1% of all subtypes, and is restricted to intrahepatic 
cholangiocarcinoma. In addition, we demonstrate that VE1 immunohistochemistry is 
a feasible approach to routinely screen for BRAF V600E mutation in biliary tract 
cancer patients, thereby facilitating the detection of rare patients who may 
benefit from BRAF mutation-targeted therapies.