About Fibrosis and Cirrhosis

Fibrosis of the liver is a common response to parenchymal cell injury induced by a wide variety of agents, including numerous chemicals and drugs such as alcohol, methotrexate, isoniazid, and thorium deioxide. The deposition of endogenous and exogenous subtances in the liver, as in myeloid metaplasia, Gaucher's disease, certain glycogen storage diseases, wilson's disease and the iron overload syndromes, is associated with fibrosis. Various infections of the liver-viral, bacterial, spicochetal, and parastic can cause hepatic fibrosis, as can chronic obstruction to blood flow and other disturbances of the hepatic circulation.
Pathogenesis, Active fibroplasma usually follows inflammation. it may be located around hepatocytes, proliferated bile ductules or macrophages and in the portal tracts. Fibrosis accompanies many hepatic disorders, but it is rarely the main characteristic of a disease. Its influence on hepatic function depends upon its localization, with pericellular fibrosis leading to hepatocellular atrophy, fibrosis around the terminal hepatic venules leading to venous outflow block, periportal fibrosis leading to portal hypertension on the basis of portal venous inflow block, and periductular fibrosis leading to cholestatis. Extensive fibrosis can result in formation of septa, which can produce significant interference with the hepatic circulation. Lobular fibrosis such as that found in certain granulomatous diseases is often associated with nothing except abnormalities of certain serum enzyme activities(e.g. alkaline phosphatase) and with BSP retention.
The disorganization of liver architecture by widespread fibrosis and nodule formation, characterized by impaired liver function. The nodules are portions of parenchyma demarcated by connective tissue. In cirrhosis all parts of the liver must be involved but large nodules can be found in which the architecture is intact. Fibrosis is not synonymous with cirrhosis; nodule formation with fibrosis is not cirrhosis. Partial nodular transformation of the liver and the solitary hyperplastic nodule or focal cirrhosis are not examples of a true cirrhosis. These lesions consist of isolated areas of fibrosis and nodularity in an otherwise normal organ. Classification of cirrhosis is;
Micronodular cirrhosis is characterized by thin regular band of connective tissue and by small nodules which vary little in size and feature no terminal hepatic veins or portal spaces.
Macronodular cirrhosis is characterized by connective tissue bands of varying thickness and by nodules which are variable in size and which do contain portal spaces and terminal hepatic veins. Previous collapse is shown by the concentration of portal spaces in the fibrosis scars.
Mixed cirrhosis combines micro and macronodular cirrhosis.


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