The usefulness of immunohistochemical staining of bile tracts in biliary atresia

Aim of the study
To assess ductular proliferation (DP) and ductal plate malformation (DPM) in biliary atresia (BA) by means of immunohistochemical staining using cytokeratins CK7 and CK19 and neural cell adhesion molecule (NCAM) antibody CD56.

Material and methods
In 10 cases of BA, liver surgical biopsies obtained at the time of hepatoportoenterostomy were stained with H&E, PAS, Gomori and Azan methods. Immunohistochemical technique was used to outline bile ducts, ductular reaction, reactive bile duct/ductules and DPM by CK7, CK19 and NCAM antibody CD56.

Results
We found fibrosis, bile stasis and mild inflammation in all cases. In the routine staining DP was not seen in 3 cases. The immunohistochemical staining by means of CK19 was helpful in the detection of DP, and allowed it to be demonstrated in all cases. The biliary epithelial cell markers for CD56, CK7, CK19 were used for demonstration of bile duct cell but not hepatocyte alterations in the structure of intrahepatic biliary ducts and different stages of maturation. CD56 as a marker of immature bile ducts was expressed on biliary epithelium of bile ducts and bizarre forms of DPM in 6 cases. The positive expression of CD56 corresponded to the co-localization of CK19 of DPM, but not CK7, to the ductular reaction at the limiting plate of portal tracts. CD7, considered as a marker of DP, also stained ductal hepatocytes and multipotential oval cells, and was a marker of DPM in 3 cases.

Conclusions
Use of CK7, CK19 and CD56 is helpful in BA diagnosis and allows differentiation of the stage of developing bile duct cells according to the expression pattern.