Multiple cysts in the hepatic hilum and their pathogenesis. A suggestion of periductal gland origin.

Multiple serous cysts involving only the hepatic hilum and larger portal tracts were found incidentally in 8 autopsy cases with several underlying liver diseases. The cysts were mostly small in size, and did not communicate with the lumena of the biliary tree. The lining of the cysts consisted of a single layer of columnar or cuboidal epithelium and the surrounding fibrous tissue was scanty. These were not associated with polycystic disease of the kidneys or cystic dilatation of the biliary tree. Cysts were absent in the liver parenchyma and an association with von Meyenburg complexes was rare. In the vicinity of the cysts there were many lobules of the glands which are physiologically present in the periductal connective tissue of the large intrahepatic bile ducts. It was noted that some of these glandular elements around the cysts disclosed varying degrees of cystic luminal dilatations. Almost all patients with such cysts had severe portal hypertension and over a half had occluding thromboemboli in the portal veins. These results lead us to propose the hypothesis that multiple cysts involving the hepatic hilum and the larger portal tracts are derived from the periductal glands in close association with an intrahepatic circulatory disturbance of the portal venous system.