A 40-year-old man with primary sclerosing cholangitis (PSC) and ulcerative colitis undergoes liver biopsy, which shows periductal onion-skin fibrosis. Which pattern of biliary involvement distinguishes large-duct PSC from IgG4-related sclerosing cholangitis, and what is the key pathological difference?
- A PSC shows granulomatous cholangitis with epithelioid granulomas surrounding bile ducts; IgG4-SC shows periductal onion-skin fibrosis with eosinophilia
- B PSC shows interface hepatitis with lymphoplasmacytic infiltrate indistinguishable from autoimmune hepatitis; IgG4-SC shows biliary ductopenia
- C PSC shows periductal concentric fibrosis with progressive ductal obliteration and cholestasis; IgG4-SC shows storiform fibrosis with abundant IgG4+ plasma cells (>10/HPF) and obliterative phlebitis ✓
- D PSC and IgG4-SC are histologically identical and can only be distinguished by serum IgG4 levels
Explanation
PSC is characterized by the 'onion-skin' periductal concentric lamellar fibrosis with progressive luminal obliteration, evolving to fibrous obliterative cholangitis; there are no IgG4-positive plasma cells. IgG4-related sclerosing cholangitis (IgG4-SC) shows storiform (cartwheel-pattern) fibrosis, a dense lymphoplasmacytic infiltrate with >10 IgG4+ plasma cells per HPF (often >50), and obliterative phlebitis — features of the IgG4-related disease (IgG4-RD) spectrum. IgG4-SC, unlike PSC, responds dramatically to corticosteroids; this distinction is critical for management.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.