Current concepts in the immunohistochemical evaluation of liver tumors

Figure 2 Hepatocellular adenoma. A and B: HNF1α-inactivated hepatocellular adenoma (HCA) with marked steatosis [A, hematoxylin and eosin (HE) stain, × 20] and loss of liver fatty acid binding protein (LFABP) expression by immunohistochemistry (left) in comparison to non-neoplastic liver (right) [B, anti-LFABP/3,3’-diaminobenzidine (DAB), × 1]; C and D: Inflammatory HCA with dilated sinusoids (telangiectasia, black arrowheads) and patchy inflammation (blue arrowheads) (C, HE stain, × 5) and diffuse serum amyloid A staining by immunohistochemistry (D, anti-serum amyloid A/DAB, × 5); E and F: β-catenin-activated HCA with strong diffuse staining for glutamine synthetase (upper left), in comparison to centrilobular staining of normal liver (lower right) (E, HE stain, × 20; F, anti-glutamine synthetase/DAB, × 1).