International consensus on histologic diagnosis of early hepatocellular neoplasia.

1. The precursor lesions for the development of hepatocellular carcinoma are believed to be high-grade dysplastic nodules. These lesions have atypical and proliferative features that distinguish them from normal or cirrhotic liver but are not sufficient for the diagnosis of carcinoma. 2. Individual HGDN are often heterogeneous and complete sampling may reveal regions of carcinoma within these otherwise benign lesions. 3. Invasion of stroma is considered a definitive feature of HCC. However, this feature is not always present in early HCC and is seldom found in needle biopsies. 4. Accurate diagnosis of dysplastic nodules and well-differentiated HCC requires skill and experience. However, accurate diagnosis with needle biopsies may be impossible if the highest grade of atypia is not sampled. Fine needle aspiration is not appropriate for small lesions that are expected to be early hepatic neoplasia. This technique should be reserved for suspected moderate- or poorly differentiated HCC.