Clincopathological features of Intrahepatic cholangiocarcinoma arising in the bile duct adenoma

Objective Bile duct adenoma（BDA） is a very rare form of benign bile duct lesion.This study aimed to evaluate the potential malignant transformation of BDA in the liver in order to improve the diagnosis and predicting the prognosis of BDA. Methods Three cases of intrahepatic cholangiocarcinoma arising from BDA were clinicopathologically evaluated and subjected to immunohistochemical examination by a panel of antibodies using the EnVision system.Relevant literature about BDA was reviewed. Results Three females were enrolled in this study.Their chief complaints were Abdominal swelling and pain.Microscopic findings indicated the tumors were composed of many normal looking bile ductules with a scanty to moderate amount of surrounding connective tissue.The stroma showed mild inflammation with predominant lymphocytes.The lumen of the ductules were narrow or slightly dilated.In addition,markedly atypical and irregularly shaped bile ductules of various sizes were noted and some of them invaded the stroma and extended into the adjacent liver parenchyma.The transitional zone from the apparently benign bile ductules to markedly atypical bile ductules was present.Mitotic figures were occasionally seen.In one tumor,areas,of cystically dilated ductules with brown bile plugs were observed,which simulate the bile duct hamartoma（BDH）.Immunohistochemical analysis showed positive cytokeratin 19 staining in the neoplastic epithelium and positive Her-2 staining in cholangiocarcinoma area. Conclusion Cholangiocarcinoma can develove from BDA indicating that BDA may be a precancerous lesion with the potential of malignant transformation.