A 38-year-old woman with primary sclerosing cholangitis (PSC) and inflammatory bowel disease undergoes liver transplantation. Cholangiography of the explant shows multifocal stricturing and dilatation of both intrahepatic and extrahepatic bile ducts. ERCP prior to transplant showed 'beaded' appearance. What is the pathological basis of the ductal changes in PSC?

• A Granulomatous destruction of small bile ducts (florid duct lesion) as in primary biliary cholangitis
• B IgG4-positive plasma cell infiltration of the bile duct wall with storiform fibrosis, as seen in IgG4-related cholangiopathy
• C 'Onion-skin' periductal concentric fibrosis obliterating medium-sized bile ducts, driven by periductal inflammation with eventual ductal obliteration and replacement by fibrous cords ✓
• D Eosinophilic infiltration of bile duct epithelium causing segmental necrosis and stricture

Explanation

Primary sclerosing cholangitis (PSC) is characterised pathologically by 'onion-skin' periductal concentric fibrosis — layers of collagen deposited around medium and large bile ducts in a lamellar pattern around the duct lumen. This periductal fibro-obliterative process is thought to be driven by autoimmune-mediated injury, possibly involving gut-liver homing of activated T-cells aberrantly trafficking to bile ducts (the 'gut-liver axis' in IBD-PSC). Progressive fibrosis obliterates bile ducts, creating the alternating strictures and dilations ('beaded' appearance) on cholangiography. The 'florid duct lesion' with granulomatous destruction characterises primary biliary cholangitis (PBC). IgG4-SC is histologically similar to PSC but is distinguished by IgG4+ plasma cell infiltration, storiform fibrosis and obliterative phlebitis.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.