Diagnostic utility of thyroid transcription factor-1 in the differential diagnosis of hepatocellular carcinoma, cholangiocarcinoma and metastatic carcinoma

Abstract

<h3>Aim</h3> Hepatocellular carcinoma (HCC) is a common, highly fatal malignancy in Asia. Its biopsy diagnosis can be difficult because of morphological similarities with other common hepatic mass lesions such as cholangiocarcinoma and metastatic tumours. Thyroid transcription factor-1 (TTF-1) is selectively expressed in thyroid and lung tissues, with primary epithelial carcinomas from these organs showing strong nuclear immunopositivity. Recently cytoplasmic TTF-1 positivity has been reported in hepatocytes. We aimed to investigate whether TTF-1 expression may be useful in differentiating HCC from common hepatic mass lesions in diagnostic liver biopsies. <h3>Methods</h3> Archived formalin-fixed, paraffin-embedded liver biopsies of confirmed HCC, cholangiocarcinoma and metastatic carcinoma were examined for TTF-1 immunohistochemical expression. <h3>Results</h3> TTF-1 positivity (cytoplasmic, coarse granular) was detected in 19/25 (76%) HCC, 0/12 (0%) cholangiocarcinoma and 1/25 (4%) metastatic carcinoma (positive predictive value=95%;negative predictive value=86%). TTF-1 was expressed in five (100%) nuclear grade 1, 11 (79%) grade 2, and three (50%) grade 3 HCC. <h3>Discussion</h3> Our study suggests that TTF-1 expression has diagnostic utility in differentiating HCC from other tumours involving the liver. In communities where both HCC and cholangiocarcinoma are common, there is justification for including TTF-1 in the immunohistochemical evaluation of liver tumour biopsies.