Difference in tissue expression of tumour markers CA 19-9 and CA 50 in hepatocellular carcinoma and cholangiocarcinoma.

The expression of tumour markers CA 19-9 and CA 50, defined by the monoclonal antibodies 1116 NS 19-9 (19-9 antibody) and C 50, was studied by the immunoperoxidase technique in formalin-fixed, paraffin-embedded tissue sections from 11 hepatocellular carcinomas and 10 cholangiocarcinomas of the liver, and from specimens of normal liver and liver cirrhosis. The 19-9 and C 50 antibodies react with sialosylfucosyllactotetraose, corresponding to sialylated blood group antigen Lewis, and the C 50 antibody also with another sugar moiety, sialosyllactotetraose. Neither marker was cancer specific. The CA 19-9 and CA 50 antigens are normal constituents of bile ducts. Nine out of 10 cholangiocarcinomas stained for CA 50, and eight out of 10 for CA 19-9. There was no apparent difference between the staining pattern of CA 19-9 and CA 50. Hepatocellular carcinomas were consistently negative for both markers. Thus, hepatocellular carcinomas and cholangiocarcinomas showed a clear difference in the reactivity for tumour marker antigens CA 19-9 and CA 50. This difference might be of clinical importance in the differential diagnosis between hepatocellular carcinoma and cholangiocarcinoma.