The diagnostic value of cytokeratins and carcinoembryonic antigen immunostaining in differentiating hepatocellular carcinomas from intrahepatic cholangiocarcinomas.

AIM: To study the differences between the hepatocellular carcinoma (HCC) and peripheral type of cholangiocarcinoma (CHC) using cytokeratin (CK) and carcinoembryonic antigen (CEA) expressions and assessing their accuracy on paraffin sections in the differential diagnosis. MATERIAL AND
METHOD: The following antibodies were analyzed: AB1 complex (anti CK9-CK20), AB2 complex (anti CK1-CK8), pCEA, and the monoclonal antibodies against cytokeratins CK7, CK8/18, CK17 and CK19. In the mmunohistochemical studies, 15 selected surgically resected liver tumors, 10 HCCs and 5 CHCs, with well established diagnosis (by morphological criteria) were included. Other markers, such as AFP si CA 19-9, were not available.
RESULTS: No CHC, but 50% of HCCs were positive for CEA, presenting a canalicular staining pattern. For CK 7, all but one (which was focally positive), meaning 80% of CHCs were diffusely positive, whereas only two HCCs were positive. For CK 19, 80% of CHCs were diffusely positive, while all but two HCCs (a moderately and a poorly differentiated tumor) were negative. For CK 8/18, 70% of HCCs were diffusely positive, whereas only 20% of CHCs were positive. For CK 17, 60% of CHCs were positive, while all HCCs were negative. 80% of CHCs were positive for AB1 anti-CKs complex, whereas only 50% of HCCs were positive, and relating to AB2 anti-CKs complex, 50% of HCCs were diffusely positive and only 20% of CHCs.
CONCLUSION: The immunohistochemical expression of CKs and CEA might be considered helpful in addition to other diagnostic criteria for the differential diagnosis of primary carcinomas of the liver, especially in difficult cases.