Differential diagnosis of hepatocellular nodular lesions.

The great advances in radiologic imaging of the last two decades have focused attention on hepatic nodular lesions. Various entities with a nodular appearance are predominantly composed of hepatocytes or tumor cells of hepatocytic origin, including benign and malignant neoplasms as well as tumorlike lesions. Differential diagnosis of these nodules can often be difficult, especially in the limited material of a needle biopsy specimen. The histological features that can be of help in this regard are the focus of this review. In noncirrhotic livers, differential diagnoses include liver cell adenoma, focal nodular hyperplasia, large regenerative nodule, nodular regenerative hyperplasia, partial nodular transformation, compensatory hyperplasia, focal fatty change, and well-differentiated hepatocellular carcinoma. Poorly differentiated hepatocellular carcinoma must be distinguished from other malignant tumors, especially metastatic, poorly differentiated adenocarcinoma. In cirrhotic livers, the differential diagnoses include large regenerative nodule, focal fatty change, low-grade dysplastic nodule, high-grade dysplastic nodule, and hepatocellular carcinoma.