Three-dimensional reconstruction of hepatic bridging fibrosis in chronic hepatitis C viral infection

Background/Aims: Fibrosis in chronic hepatitis C infection begins in portal tracts, and can progress to 'bridging fibrosis' and eventually lead to cirrhosis. All current fibrosis staging systems are based on these three conceptual fibrosis stages (portal fibrosis, bridging fibrosis, cirrhosis) and vary only in how these stages are further subdivided. Despite the importance of bridging fibrosis, little is known about its three-dimensional characteristics. Methods: Foci of bridging fibrosis were digitally reconstructed in three dimensions on two separate liver specimens with chronic hepatitis C viral infection. The amount of portal fibrosis was then correlated with bile duct diameter on trichrome-stained sections. Results: After three-dimensional reconstruction, the bridges were seen to represent webs or membranes of fibrosis located at branch points of the portal tracts that extended between two portal branches, much like the webbing between the thumb and forefinger in a baseball-mitt. Direct measurements indicated that early portal fibrosis was associated with portal tracts containing bile ducts of approximately 18-19 μm diameter. Conclusions: Fibrosis bridges are located at branch points of portal tracts and are composed of three-dimensional webs or membranes that extend between portal tracts; when viewed as two dimensions on a glass slide, a 'bridge' of nbrosis is seen.