Figure 4

Immunohistochemical features of pigmented hepatocellular neoplasms. (a–c) Glypican-3: the pigment within tumor cells is highlighted by glypican-3 immunostain (a, 100 ×). The staining pattern can be pericanalicular (b, 400 ×) or more diffuse (c, 400 ×) in cases with heavy pigment deposition. (d): Ki-67 (400 ×): this is the only example of a hepatocellular carcinoma showing increased proliferative index by Ki-67. (e): Liver fatty acid-binding protein (40 ×): this example of a HNF-1α inactivated hepatocellular adenoma shows loss of liver fatty acid-binding protein expression in the tumor (left) compared with the non-neoplastic liver (right). (f and g): Glutamine synthetase and β-catenin: this example of a β-catenin activated hepatocellular neoplasm of uncertain malignant potential shows diffuse expression of glutamine synthetase (f, 40 ×) in the tumor (f, right) in comparison with localized perivenular staining in the non-neoplastic liver (f, left). Aberrant nuclear expression of β-catenin was also present (g, 200 ×). (h and i) C-reactive protein and serum amyloid-A: this example of inflammatory-type hepatocellular adenoma shows diffuse strong expression of both C-reactive protein (h, 40 ×) and serum amyloid-A (i, 200 ×).