Comparative immunohistochemical study of primary and metastatic carcinomas of the liver.

Distinguishing primary hepatocellular carcinoma (HCC) from metastatic carcinomas to the liver is often difficult, if not impossible, particularly in needle biopsy and fine-needle aspiration specimens. In an attempt to identify a specific immunohistochemical profile that would distinguish HCC from metastatic carcinomas, we studied 56 HCCs, 8 cholangiocarcinomas, and 24 metastatic adenocarcinomas with monoclonal antibodies to alpha-fetoprotein (AFP), keratin (AE1, AE3, and CAM5.2), Leu-M1, human milk fat globule (HMFG-2), tumor-associated glycoprotein-72(B72.3), epithelial specific membrane antigen (Ber-EP4), and BCA-225 (CU-18). Both monoclonal and polyclonal (mCEA and pCEA) antibodies to carcinoembryonic antigen also were used. Metastatic adenocarcinomas were often positive for CU-18(71%), Leu-M1 (75%), B72.3 (50%), HMFG-2 (67%), Ber-EP4(83%) and mCEA(71%). Using these antibodies, the frequency of positivity for HCC was 9%, 16%, 11%, 20%, 36%, and 11%, respectively. CU-18 was the only monoclonal antibody in which there was a significant difference in positive rates between HCC and metastatic adenocarcinomas. Most HCCs (71%) revealed a bile canalicular staining pattern with pCEA. Because this staining pattern was absent in metastatic carcinomas, pCEA appears to be useful in confirming a diagnosis of HCC. AE1, AE3 and CAM5.2 antibodies were not useful in distinguishing HCC from metastatic carcinomas. Each cholangiocarcinoma shared a staining profile similar to that of metastatic carcinomas.