Cholangiocarcinoma arising in von Meyenburg complexes: report of four cases.

Although von Meyenburg complexes (VMC) are largely considered to be innocuous, neoplastic transformations have been described. The present report describes four cases of cholangiocarcinoma (CC) occurring on a background of VMC. The patients were all male and aged 69, 59, 68 and 75 years, respectively. While two patients were asymptomatic, the other two had a history of colon cancer. Radiologically the tumors measured 3, 4, 4.5 and 10 cm and were well enhanced from the arterial to delayed portal phase. Microscopically, the tumor consisted of multiple foci of characteristic VMC, and had a gradual transition from VMC to hyperplasia or dysplasia and well- to moderately differentiated adenocarcinomas. One patient had combined hepatocellular carcinoma (HCC) and CC, occurring in the high grade dysplastic nodule and VMC. On immunohistochemistry the epithelial cells of the VMC and CC were immunopositive for cytokeratin (CK) 7 in three patients, with another patient being focally positive only for CK19. The Ki-67 labeling indices increased from the VMC to the dysplastic areas and then to the carcinomas. As a potentially precancerous lesion, VMC should be carefully followed up in terms of any size increases. Thus, biopsies are essential to determine any proliferative epithelial changes including dysplasia and malignant transformation.