Nonneoplastic Hepatobiliary Disease

Abstract

The liver is susceptible to infection by a number of agents either as a preferential site of infection as with the hepatotropic viruses and the liver flukes; or because organisms gain access through the biliary system, the portal vein or the hepatic artery as with ascending cholangitis, pyogenic infections, and certain parasitic infections. The central role of the liver in drug metabolism predisposes it to an impressive array of drug-induced injuries which may mimic any of the other known patterns of liver injury and should always be considered in the differential diagnosis of any liver disease. The liver may accumulate fat due to chronic alcohol abuse or secondary to obesity, diabetes and hyperlipidemia. Steatosis may progress to steatohepatitis, fibrosis, and cirrhosis. A number of genetic, inherited and metabolic diseases result in liver disease. Some such as cystic fibrosis, alpha-1 antitrypsin deficiency, Wilson disease, and genetic hemochromatosis may progress to cirrhosis. Others such as Dubin–Johnson syndrome may be benign and nonprogressive. A number of inherited diseases also affect the biliary system; these include polycystic liver disease, choledochal cyst, Caroli’s disease and progressive familial intrahepatic cholestasis. Finally, obstruction of the hepatic venous outflow may occur in chronic right-sided heart failure, Budd–Chiari syndrome and veno-occlusive disease, leading to portal hypertension, ascites and when chronic, to bridging fibrosis.

Notwithstanding the number of conditions discussed in this chapter, the majority of cases of liver disease can be attributed to the big four: chronic hepatitis C infection, chronic hepatitis B infection, alcoholic liver disease, and nonalcoholic fatty liver disease. This list is followed by the autoimmune liver diseases and drug-induced liver injury in the more developed countries; and by a host of viral and parasitic infections in less developed and tropical parts of the globe.