BRCA1/BRCA2 Double Heterozygosity Presenting as Intrahepatic Cholangiocarcinoma

We report a case of BRCA1/BRCA2 double heterozygosity-a rare condition with an estimated prevalence of fewer than 1 in 100,000 individuals in unselected populations-identified through tumor genomic profiling in a 50-year-old Japanese woman with intrahepatic cholangiocarcinoma and no prior cancer history. Germline testing confirmed BRCA1 c.2389_2390del and BRCA2 c.5621_5624del. This case demonstrates that intrahepatic cholangiocarcinoma can be a sentinel malignancy of BRCA-related cancer predisposition, thus underscoring the importance of germline testing.