Structurally liver is a heterogenous (heterogenous means ‘diverse’) organ and is made of three major distinct tissues. Majority of this is the liver parenchyma or the liver substance formed by the liver cells (medically termed as ‘hepatocytes’) which forms the primary component of liver; the other component is the biliary tissue which constitutes the tubular biliary system and is formed by biliary cells (medically referred to as ‘cholangiocytes’) and the third being the blood vessels which carries blood to, through and from liver to heart.

Disease of liver can primarily involve any of these three entities and hence can be categorized as:

1. Diseases affecting liver substance (liver cells)

1. Hepatitis (eg. Viral Hepatitis)

2. Cirrhosis

3. Space occupying lesions (eg. Liver abscess, Hydatid Cysts, Liver Cancers)

4. Liver Infiltrations (eg. Fatty Liver, Glycogen storage disorders, hemochromatosis, amyloidosis)

5. Metabolic & Functional disorders

   1. Hereditary: eg: Wilson’s Disease, Tyrosinemia

   2. Acquired: eg: Cholestasis of pregnancy

2. Diseases affecting the liver biliary tree

1. Biliary infection (eg: Cholangitis, Primary Sclerosing Cholangitis)

2. Biliary obstruction (eg: Biliary atresia, biliary stones, biliary cancers)

3. Diseases affecting the blood vessels of the liver

1. Budd Chairi Syndrome (blockage of hepatic veins)

2. Portal vein thrombosis (blockage of portal vein)

Many of these diseases are benign and can be treated by timely medical or minimal surgical intervention but can become progressive and chronic (long standing) either if timely corrective action is not taken or if any complication occurs. Some of these diseases can be congenital or hereditary and have potential to progress inspite of all the medical treatment. The third category of liver diseases are the liver cancers. Liver cancers mostly develop over some pre-existing chronic and progressive disease but sometimes can develop de novo (spontaneously) too, however such incidences are very rare.

What ever may the original cause of liver disease or problem, once it becomes chronic and progressive it is medically referred to as Chronic Liver Disease (or CLD) and it follows a similar course and ultimately ends up in a stage of advanced liver damage medically referred to as Liver Cirrhosis.