Morphogenesis of liver cirrhosis

What is the morphological essence of hepatic sinusoid capillarization?

The morphological essence of sinusoid capillarization consists in the transformation of permeable hepatic sinusoids into ordinary capillaries with a dense basement membrane. The process includes the following changes in the perisinusoidal space (Space of Disse):

• Matrix accumulation — excessive deposition of extracellular matrix components and formation of a dense collagen framework.
• Structural remodeling — appearance of a basement membrane and collagen fibers in the sinusoid walls, which are normally absent.

This creates a capillary-parenchymal block — a mechanical obstacle to metabolic exchange between blood and hepatocytes.

What are the precise morphometric criteria for micronodular liver cirrhosis?

The precise morphometric criterion for micronodular liver cirrhosis is the formation of regenerative nodules no more than 3 mm in diameter (usually about 1–3 mm). Additional morphological characteristics:

• Regenerative nodules — uniform in size (monomorphic), represented by small pseudolobules.
• Stroma — nodules are separated by thin layers of connective tissue (septa of uniform width) forming a fine reticular network.

This variant of parenchymal remodeling is considered characteristic of the early stage of cirrhosis formation.

What microscopic features distinguish a pseudolobule from a normal liver lobule?

A pseudolobule (regenerative nodule) in cirrhosis is characterized by a disruption of normal liver angioarchitecture. Its microscopic features include:

• Surrounding connective tissue — regenerative nodules are surrounded on all sides by connective tissue (septa).
• Disruption of the trabecular structure — the normal trabecular architecture of the liver is disrupted, and the radial orientation of liver trabeculae is lost.
• Central vein — absent within the nodule or displaced to the periphery.
• Hepatocyte regeneration — nodular regeneration of hepatocytes is observed within the pseudolobules; the regenerative nodules consist of dividing hepatocytes, large and sometimes multinucleated.

What is incomplete septal liver cirrhosis?

Incomplete septal liver cirrhosis is a variant of the disease in which typical pseudolobules are not defined, and signs of regeneration within nodules are not clearly expressed. Its main morphological features are:

• Septa — presence of thin, sometimes incomplete fibrous septa between large nodules.
• Connections — septa connect adjacent portal tracts.
• Blind ends — some septa may end blindly in the liver parenchyma.

Between which vessels do intrahepatic portosystemic shunts form in cirrhosis?

Intrahepatic portosystemic shunts in cirrhosis form between the branches of the portal and hepatic veins. The mechanism and consequences of their formation:

• Localization — these direct vessels form within the connective tissue layers (septa).
• Hemodynamics — due to impaired blood flow in the pseudolobules, blood rushes into the hepatic veins, bypassing the regenerative nodules.
• Pathogenesis — shunting causes microcirculation impairment, parenchymal hypoxia, and progressive dystrophy and necrosis of hepatocytes.