Developmental histology of the portal plate in biliary atresia: observations and implications.

Purpose: The key characteristic of biliary atresia (BA) is obliteration of the extrahepatic bile ducts at the level of the porta hepatis. We aimed to relate the immunohistochemical features of remnant biliary ductules at the porta hepatis with clinical features and outcomes.

Methods: Samples were immunostained with anti-cytokeratin 20 (CK20), vimentin and alpha-smooth muscle actin (aSMA). Primary outcome was set as clearance of jaundice (bilirubin ≤ 20 μmol/L) following Kasai portoenterostomy (KPE).

Results: Eighty-two cases were classified into syndromic BA (n = 10), cystic BA (n = 7), CMV IgM+ BA (n = 9) and isolated BA (n = 56). CK20 expression was confirmed in 40/82 (49%), and vimentin expression in 19/82 (23%). aSMA was negative in all cases studied. CK20 expression was less common in isolated BA (n = 20/56, 36%) compared to CMV IgM+ BA (n = 8/9, 89%), cystic BA (n = 7/7, 100%) (isolated BA vs non-isolated BA, P = 0.0008). There was no difference in vimentin expression among the sub-groups (isolated BA vs. non-isolated BA; P = 0.39). CoJ was achieved in 52/82 (63%) overall with significant difference depending simply on sub-group [e.g. syndromic BA 9/10 (90%)]. CK20 expression was associated with a diminished rate of CoJ in the entire cohort [CK20+ 32/56 (57%) vs. CK20- 20/26 (77%); P = 0.04]. By contrast no correlation was observed between vimentin expression and CoJ (P = 0.13).

Conclusion: CK20+ expression was associated with reduced clearance of jaundice in BA and a trend towards reduced native liver survival.