Pathologic assessment of liver cell dysplasia and benign liver tumors: differentiation from malignant tumors.

Recent developments in the pathologic assessment of several benign hepatic processes are reviewed, with particular emphasis on distinguishing these processes from malignant lesions. Liver cell dysplasia remains a controversial lesion, with mounting evidence to support its preneoplastic nature. Adenomatous hyperplastic nodules are large regenerative nodules in cirrhotic livers, and may also have malignant potential. Distinguishing these nodules from hepatocellular carcinoma by histology may become increasingly important, with the advent of more sensitive imaging techniques. Differentiating features of noncancerous biliary epithelium versus well-differentiated cholangiocarcinoma, sclerosing hemangioma versus epithelioid hemangioendothelioma, and angiomyelolipoma versus the clear cell variant of hepatocellular carcinoma are also presented and discussed.