Recent immunohistochemical markers in the differential diagnosis of primary and metastatic carcinomas of the liver.

Differential diagnosis of primary and metastatic carcinomas of the liver can be problematic and may require immunohistochemical work-up. Recently, new immunohistochemical markers have been introduced with promising results in this area. We studied three of these markers, human hepatocyte antibody (HepPar-1), human epithelial-related antigen (MOC-31), and thyroid transcription factor-1 (TTF-1), in cell-block sections of fine-needle aspirations from 30 hepatocellular carcinomas and 27 metastatic carcinomas from various sites. Of 27 metastatic carcinomas, all but one were positive for MOC-31 and, all but one were negative for HepPar-1. TTF-1 was positive only in the nuclei of metastatic poorly differentiated neuroendocrine carcinoma from the lung. Of 30 hepatocellular carcinomas, 26 were positive for HepPar-1 and all were negative for MOC-31, while TTF-1 showed cytoplasmic staining in 23 cases. HepPar-1, MOC-31, and TTF-1 are complementary markers in the differential diagnosis of primary and metastatic carcinomas of the liver, with high sensitivity and specificity.