Evidence for the neoplastic transformation of Von-Meyenburg complexes.

Von-Meyenburg complexes (VMC) are seen frequently in the liver and are largely considered to be innocuous, with only 11 cases reported in the literature of neoplastic transformation of VMCs. The authors report three cases of cholangiocarcinoma, each occurring in a background of fibrosis and nodularity that was reported initially as micronodular cirrhosis. Although the livers showed cirrhosis, the central veins were often preserved, and regenerative activity was patchy and focal. Histologic examination revealed many VMCs, and a gradual transition from VMCs to hyperplastic or adenomatous lesions and cholangiocarcinoma. The adenomatous lesions consisted of extensive replacement of the parenchyma by tumor-like nodules of ductular proliferations without obvious features of malignancy. All three patients were older than 60 years of age and had portal hypertension. Computed tomographic scans showed multiple, small renal cysts in one patient. Immunohistochemical staining showed positivity for epithelial membrane antigen, carcinoembryonic antigen, and keratins (AE1/AE3 and CAM5.2) in tumor cells, consistent with cholangiocarcinoma. The pattern of fibrosis and nodularity in these cases is not typical of either congenital hepatic fibrosis or usual cirrhosis. The authors propose that these patients represent another aspect in the spectrum of ductal plate malformations that may be modified by other factors such as alcohol, drugs, or infection. To their knowledge, neoplastic transformation of VMCs in the background of such changes has never been reported before.