Diagnosis of Focal Nodular Hyperplasia (FNH) after Liver Transplantation

Figure 4

(a) The boundary between normal liver tissue and the lesional tissue is difficult to appreciate on H&E stain on low power (H&E stain, 20x magnification). (b) However, immunohistochemical stain for glutamine synthetase highlights the lesional area with patchy brown staining. Nodular architectural typical for FNH is also more evident. Adjacent normal liver tissue (arrows) shows the characteristic perivenular staining only (glutamine synthetase immunohistochemical stain, 20x magnification). (c) Large abnormal muscular arteries (arrow) without associated bile ducts of similar size are seen, a characteristic feature of FNH (H&E stain, 100x magnification). (d) Large fibrous tracts with ductular proliferation, similar to that seen in cirrhotic livers, is seen within the lesion (H&E stain, 100x magnification). (e) On high power, the hepatocytes within the lesion appear similar in appearance to the background nonlesional hepatocytes. No significant cell plate architectural abnormality or cytologic atypia diagnostic of hepatocellular carcinoma is identified (H&E stain, 200x magnification). (f) Reticulin stain highlights fibrous tracts within the lesion (arrows). Also, significant thickening of the hepatocellular plates, a feature of hepatocellular carcinoma, is absent (reticulin stain, 100x magnification).

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