PCEA CANALICULAR IMMUNOSTAINING IN FINE-NEEDLE ASPIRATION BIOPSY DIAGNOSIS OF HEPATOCELLULAR-CARCINOMA

OBJECTIVE: To assess the usefulness of bile canalicular polyclonal car cinoembryonic antigen (pCEA) immunostaining in fine needle aspiration biopsy (FNAB) diagnosis of hepatocellular carcinoma (HCC). STUDY DESIG N: Hepatic FNAB with cell blocks of 72 confirmed and 6 possible HCC an d 23 non-HCC malignancies (controls) were analyzed. Sections were stai ned with antibody to pCEA using the streptavidin biotin - immunoperoxi dase method and results correlated with tumor grade and other paramete rs used in HCC diagnosis. RESULTS: Canalicular pCEA staining was obser ved in 60 (83%) of the 72 HCC. This category comprised 29%, 31%, 36% a nd 4% grade 1-4 tumors, including 7 small cell, 4 clear cell and 2 gia nt cell variants. With increasing anaplasia, the canaliculi became inf requent, irregularly distributed, and increasingly distorted and inter rupted. Canalicular staining helped distinguish clear and small cell v ariants from metastatic renal cell carcinomas and neuroendocrine tumor s, respectively. Of the six problematic cases, one was confirmed to be HCC with plasmacytoid features and five to be adenocarcinomas, of whi ch three could have been combined hepatocellular-cholangiocarcinomas. Liver cell dysplasia also displayed an abnormal canalicular pattern. N o cytoplasmic staining was seen in pure HCC. CONCLUSION: pCEA immunost aining cannot separate malignant, dysplastic or benign hepatocytes. It is usually not required in cytodiagnosis of most HCC. However, it is most helpful in confirming atypical variants of HCC, which may mimic o ther tumors.