BRAF‐associated bile duct adenomatosis: a new entity?

Bile duct adenomas (BDAs) are benign intrahepatic biliary proliferations consisting of bile ducts arranged in small and tortuous tubules and embedded in a dense fibrous stroma [1]. Microscopically, tubules are lined by a single layer of cuboidal to columnar cells with nuclei showing neither atypia nor mitoses. BDAs were formerly considered reactive by some authors [2,3]. Recurrent BRAF V600E mutations were however further identified in these lesions, supporting the hypothesis that they are true neoplasms [4,5]. They are most often incidentally identified during intra-abdominal surgery and the main differential diagnosis of BDAs is metastatic adenocarcinoma, as mentioned by Levin et al. in the first report of bile duct adenomatosis of the liver [6].