Mesenchymal hamartoma of the liver--an autopsy case with serial sections and some comments on its pathogenesis.

An autopsy case of mesenchymal hamartoma of the liver was reported and from the macroscopical observation and serial sections of the tumor the following findings were found: (1) macroscopically the tumor is supplied by only one large triad, (2) in the tumor hepatic lobular structure is fundamentally preserved and prolifereated bile ducts with surrounding fibrosis and many bile thrombi are mainly elongated and dilated Hering's canals, (3) the cysts connect with dilated interlobular bile ducts, (4) there are two portions, where connection of bile ducts is incomplete, that is, from Hering's canals to interlobular bile ducts and from interlobular ducts to large ducts in the large triad of (1), (5) almost all portal veins in the large triad of (2) are stenosed or obliterated by loose intimal fibrosis. From these findings it is considered that intrahepatic bile duct obstruction resulting in regional biliary cirrhosis is the fundamental process of this disease, and in addition the role of hemodynamic disturbance was discussed.