Background: Epstein-Barr virus (EBV) was found to be associated with many cancers. Only a few cases of EBV-associated cholangiocarcinoma were reported and most of them were lymphoepithelioma-like tumors. The objective of this study was to determine the prevalence of EBV in intrahepatic cholangiocarcinoma in the Thai population.

Material and methods: A total of 40 cholangiocarcinoma tumors were retrieved by simple random sampling. EBV status was assessed by EBV-encoded small RNA (EBER) in situ hybridization from formalin-fixed paraffin-embedded (FFPE) tumor samples. The association between EBV status and clinicopathological characteristics was analyzed using Fisher's exact test, and survival analysis was done using the Kaplan-Meier method.

Results: Out of 40 intrahepatic cholangiocarcinoma tumor samples, 3 (7.5%) were positive for EBV by EBER in situ hybridization. The median age of EBV-positive patients was lower than the EBV-negative group (52 vs 64 years). All three EBV-positive intrahepatic cholangiocarcinoma cases were presented in stage I (T1N0M0). Two patients were well-differentiated adenocarcinoma and 1 was mucinous cystadenocarcinoma. There was a trend toward better survival was seen in EBV-positive patients (p=0.085).

Conclusion: EBV-associated intrahepatic cholangiocarcinoma is rare, only 7.5%, even in the endemic area.