The liver in autosomal dominant polycystic kidney disease. Implications for pathogenesis

A histomorphometric and clinico-pathologic analysis of 26 autopsy cases of autosomal dominant polycystic kidney disease (ADPKD) showed that (1) the density of biliary microhamartomas (BMHs) and the stage of polycystic liver disease were strongly correlated, and (2) both were positively correlated with the stage of renal dysfunction and age at autopsy. Using multiple linear regression analysis, only the stage of renal dysfunction was significantly predictive of the density of BMHs, but both variables were simultaneously predictive for the stage of polycystic liver disease. On serial sections, 41.4% of cysts were connected to BMHs and 81.0% of BMHs to portal tracts. Bile-like material was found in 10.7% of BMHs. Flat or polypoid hyperplasia of the epithelium was observed in 2.7% of cysts. These results support the long-maintained view that hepatic cysts in ADPKD result from cystic dilatation of BMHs. They indicate, however, that the number of BMHs increases during life. These observations are consistent with the hypothesis that hepatic and renal cysts in ADPKD have similar pathogeneses, that BMHs and hepatic cysts result from hyperplasia of the bile duct epithelium, and that as they grow, the hepatic cysts become disconnected from the biliary ducts from which they are derived.