Pictures of focal nodular hyperplasia and hepatocellular adenomas

This practical atlas aims to help liver and non liver pa-thologists to recognize benign hepatocellular nodules on resected specimen. Macroscopic and microscopic views together with immunohistochemical stains illustrate typical and atypical aspects of focal nodular hyperplasia and of hepatocellular adenoma, including hepatocel-lular adenomas subtypes with references to clinical and imaging data. Each step is important to make a correct diagnosis. The specimen including the nodule and the non-tumoral liver should be sliced, photographed and all different looking areas adequately sampled for par-affin inclusion. Routine histology includes HE, trichrome and cytokeratin 7. Immunohistochemistry includes glu-tamine synthase and according to the above results ad-ditional markers such as liver fatty acid binding protein, C reactive protein and beta catenin may be realized to differentiate focal nodular hyperplasia from hepatocel-lular adenoma subtypes. Clues for differential diagnosis and pitfalls are explained and illustrated.