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[313] Glypican-3 Immunocytochemistry in Liver Fine Needle Aspirates: A Novel Stain To Assist in Differentiation of Benign and Malignant Liver Lesions

D Kandil, G Leiman, W Trotman, M Allegretta, L Pantanowitz, R Goulart, M Evans. University of Vermont, Burlington, VT; Baystate Medical Center, Springfield, MA

Background: Glypican-3 (GPC3) is a heparan sulfate proteoglycan bound to the cell surface by a lipid anchor, regulating activity of certain cytokines, such as Wnts. Recent studies have shown that serum GPC3 levels are significantly increased in hepatocellular carcinoma (HCC) patients, but are undetectable in healthy liver donors and patients with benign liver disease. GPC3 has proven to be a promising marker of HCC in histological sections by immunohistochemistry. To our knowledge, in this study, GPC3 protein expression is explored for the first time, in liver fine needle aspirates (FNAs) by immunocytochemistry.
Design: Archival direct smear and Cytolyt-fixed (Cytyc, Boxboro, MA) material from hepatic FNAs at two institutions were retrieved; these comprised 60 slides from 20 cases of proven HCC (group A), 20 cases of metastatic adenocarcinoma to the liver (group B) and 20 cases with benign hepatocytes (group C). Following blockage of endogenous peroxidase and protein, antigen retrieval was performed. Primary antibody GPC3 (Clone 1G12, BioMosaics Inc, Burlington, VT), and secondary antibody Mouse Envision Polymer (DakoCytomation, Dako Corporation, USA) were used, followed by DAB chromogen (DakoCytomation). The slides were counterstained with hematoxylin, and examined by 5 observers. GPC3 staining intensity and pattern were graded by a 4-tier system as: negative=0, weak cytoplasmic=1, moderate cytoplasmic=2, and strong cytoplasmic with membranous accentuation=3.
Results: GPC3 immunoreactivity was cytoplasmic with membranous, and occasionally perinuclear, accentuation. Group A had stronger immunoreactivity compared with groups B and C. Group A (HCCs) showed 10% grade 0-1 and 90% grade 2-3 staining. In contrast, group B (metastatic adenocarcinoma) and C (benign hepatocytes) resulted in 100% grade 0-1 and 0% at grade 2-3. Sensitivity and specificity at grades 2-3 were 90% and 100% respectively, p <0.001.
Conclusions: In this study, 90% of HCC in archival liver FNAs were strongly positive for GPC3, with cytoplasmic accentuation present in 70%. All benign hepatocytes and metastatic adenocarcinomas were negative or stained only weakly for GPC3. Our data supports the potentially significant diagnostic utility of GPC3 in FNAs as a reliable tool in differentiating benign from malignant liver lesions, and primary liver tumors from metastases to the liver.
Category: Cytopathology

Wednesday, March 28, 2007

Poster # 42, Wednesday Morning