Liver precancerous lesions and hepatocellular carcinoma: the histology report.

The current ability to increase the survival of patients with hepatocellular carcinoma (HCC) relies upon the surveillance of cirrhotic patients. Surveillance allows HCC precursors (dysplastic nodules) and malignant tumors to be recognized at an earlier stage making cure possible. Radiology plays a major role in HCC diagnosis because HCC is characterized by neoarterial vascularisation with a typical imaging pattern. Current international guidelines have restricted the use of the liver biopsy to the characterization of hepatocellular nodules which remain diagnostically equivocal after imaging. Thus pathologists are today facing very challenging and often well differentiated lesions, leading to difficulties in distinguishing high grade dysplasia and well differentiated HCC. In this scenario novel concepts obtained through international consensus have been proposed with emphasis on HCC of small size (up to 2 cm) which includes 2 distinct types, the early and progressed HCC. In this paper we will report the main histopathological criteria of a biopsy which allow the differentiation of HCC precursors (dysplastic nodules) from well differentiated HCC with attention to the role and weight of both classical histopathological criteria and novel immunocytochemical markers. The second part of the paper is devoted to the histopathology report of HCC on surgical specimens including explanted livers and on the differential diagnosis between HCC and liver metastasis.