The strength of cytomorphology and efficacy of immuno-cytochemistry in distinguishing hepatocellular carcinoma from its mimics on fine-needle aspiration cytology

Diagn Cytopathol. 2021 Apr 30. doi: 10.1002/dc.24759. Online ahead of print.

Abstract

Background: Cytomorphologic distinction of hepatocellular carcinoma (HCC) from its mimics on fine-needle aspiration cytology (FNAC) is often problematic. The present study evaluates the strength of cytomorphology and the utility of an immuno-panel of arginase-1, glypican-3, HepPar-1, thyroid transcription factor (TTF-1) and CK-19 in resolving this diagnostic issue.

Methods: FNAC features of 71 nodular hepatic lesions were studied with an immunocyto/ histochemical (ICC/IHC) panel of arginase-1, glypican-3, HepPar-1, TTF-1 taking 10% positivity as "cut-off." Cytomorpholologic diagnoses were compared with diagnoses made on combined cytomorphologic and ICC/IHC approach.

Results: Of 71 cases, 32, 10 and 29 had histopathologic, cell block and clinico-radiologic correlation respectively with 55 metastatic adenocarcinomas (MAC), 13 HCCs and one case each of hepatic adenoma (HA), cirrhotic nodule (CN) and intrahepatic cholangiocarcinoma (CC). Cytoplasmic positivity of HepPar-1 and glypican-3 were noted in 11/13 and 8/13 HCCs respectively; while only 3/13 and 1/13 HCCs revealed cytoplasmic positivity for arginase-1 and TTF-1 respectively. Benign hepatic lesions were negative for glypican-3 and TTF-1, but expressed both arginase-1and HepPar-1. Twenty-one of 55 MACs and the lone case of CC were positive for CK-19; however, all MACs and CC cases were negative for HepPar-1, arginase-1, glypican-3 and TTF-1. The immune-panel had sensitivity, specificity and diagnostic accuracy of 100%, 88.9% and 90.6%, respectively, for differentiating HCC from its morphologic mimics.

Conclusion: Though a meticulous cytologic evaluation in conjunction with clinicoradiologic profile helps in distinguishing HCC from its benign and malignant mimics; an immunopanel of arginase-1, glypican-3, HepPar-1, TTF-1 and CK-19 drastically improves the diagnostic accuracy.

Keywords: cholangiocarcinoma; fine-needle aspiration; hepatocellular carcinoma; immunocytochemistry; metastasis; morphologic mimics.