What are liver fibrosis and steatosis?

Chronic liver diseases affect the liver tissue in various ways: fibrosis and steatosis.

Fibrosis

Any chronic attack on the liver will cause inflammation, which then leads to the formation of fibrous scar tissue in the liver, creating hepatic fibrosis. This fibrosis is therefore a scarring process that will replace damaged liver cells. The extent of this fibrosis can vary, and it is described in several stages. A normal liver is at a stage between F0 and F1. Stage F2 denotes light fibrosis, and F3 is severe fibrosis. ‘Cirrhosis’ is defined from stage F4, when scar tissue exists throughout the liver.

Fibrosis therefore disorganises the architecture of the liver both anatomically and functionally. When fibrosis reaches the cirrhosis stage, it is initially completely asymptomatic; this is the compensated cirrhosis stage, i.e. not complicated. It can be discovered fortuitously during scheduled examinations. The cirrhosis then decompensates, and liver complications appear.

• Portal hypertension which is secondary to liver fibrosis; this impedes venous circulation and causes the pressure in the portal vein to rise. It can promote haemorrhaging by bursting oesophageal varicose veins.
• Ascites which is the formation of a liquid effusion in the abdominal cavity, which can become infected.
• Icterus (jaundice).
• Hepatic encephalopathye which corresponds to neurological disorders by the accumulation of toxins that are not broken down by the liver.
• Primitive cancer of the liver, which is a final complication, and can also be called hepatocellular carcinoma.

Fibrosis is reversible if the cause of the disease is treated and if the lesions are not too severe. The liver can then resume a normal structure. The degree of fibrosis therefore constitutes an important prognostic parameter. The extent of the fibrosis is one factor affecting the diagnosis and decisions concerning therapy, and a criterion for tracking the progress of the illness and the effectiveness of therapy..

Steatosis

Liver steatosis is an accumulation of fat in the liver, making a ‘fatty liver’. It corresponds to the accumulation of lipids (triglycerides) in the liver cells (hepatocytes) and may complicate alcoholic intoxication or metabolic disorders such as Type 2 diabetes, obesity, and dyslipemia. Such steatosis can either be isolated, making it a pure steatosis, or associated with hepatitis, which makes it non-alcoholic steatohepatitis (NASH). Steatosis and NASH form non-alcoholic fatty liver disease (NAFLD). These are usually asymptomatic conditions, but they are currently becoming more common because of the increasing number of overweight patients.

The problem is that, in a small number of cases, steatosis can develop into a fibrosis that can lead to cirrhosis; which demonstrates why it is important to diagnose it.

In the general population, the incidence of steatosis estimated by ultrasound has reached 20 to 25%, and that is probably an underestimate, because ultrasound only detects major cases of steatosis.