Pathology of Liver Diseases

The hepatic primordium anlage initially appears at the end of the third week of gestation and is first seen as a hollow midline outgrowth stalk (hepatic diverticulum) of the endodermal epithelium at the distal aspect of the foregut. By the fourth week, the diverticulum enlarges from proliferation of the endodermal cell strands (hepatoblasts) and projects cranially into the mesoderm of the septum transversum, eventually giving rise to the liver hepatic parenchyma and intrahepatic ducts. The cephalic end ultimately develops into the right and left hepatic lobes, while the stalk between the diverticulum and foregut narrows and forms the extrahepatic biliary system and gallbladder. Solid cords are initially formed by proliferating endodermal cells. These eventually anastomose to form vesicles and cribriform tubules with centrally located lumenal structures (biliary canaliculi). The cords eventually merge and develop small channels and capillaries that subdivide the cords to eventually fo...

The liver is a unique organ that has numerous structural and physiological functions. It is most important when discussing liver pathology that one understands first the normal liver histology before one can best understand the basic pathophysiologic concepts of the numerous liver diseases. The pathologist plays a fundamental role in assessing the various morphologic features seen in liver tissue, whether by fine needle aspirates, needle or wedge biopsies, partial hepatectomies, liver explants, or autopsy material. The pathologist also has not only routine but also numerous special histochemical and immunohistologic stains as well. Yet correlating the histologic findings with the most pertinent clinical and laboratory data enables the pathologist to better arrive at a diagnosis and the most pertinent differential possibilities. This introductory chapter addresses all aspects of the normal liver, reviewing the embryologic development, gross and microscopic features, the pertinent intrac...