Aberrant expression of cytokeratin 7 as a histological marker of progression in primary biliary cirrhosis

AIM: We evaluated the aberrant expression of cytokeratin 7 (CK-7) in hepatocytes as a marker of cholestasis and progression in primary biliary cirrhosis (PBC). PATIENTS AND METHODS: The expression of CK-7 was studied by immunohistochemistry in 83 cases of PBC. This expression was compared with biochemical data, the deposition of copper-associated protein, and previous histological classifications. RESULTS: In normal liver, CK-7 was expressed exclusively in bile duct epithelial cells (BDE). In PBC, the expression was also observed in hepatocytes. The expression pattern was classified as follows: Grade 0, BDE as in normal; Grade 1, proliferated bile ductules; Grade 2, periportal hepatocytes in addition to proliferated bile ductules; Grade 3, intralobular hepatocytes; Grade 4, the majority of hepatocytes. The grades correlated with serum bilirubin levels but not with serum levels of biliary enzymes. A discrepancy between the CK-7 grading and Ludwig's classification was noted in cases with Stage 1 of the CK-7 grading who were considered Stage 2 or 3 in Ludwig's classification, suggesting that cholestasis and inflammatory activity might be independent events. CONCLUSIONS: These results suggest that the aberrant expression of CK-7 in hepatocytes may be a marker of chronic cholestasis and progression in PBC.