Focal nodular hyperplasia and liver cell adenoma: Radiologic and pathologic differentiation
The majority of benign liver tumors that present major diagnostic problems to the radiologist and pathologist may be classified as either focal nodular hyperplasia or liver cell adenoma. Focal nodular hyperplasia has an innocuous natural history. Liver cell adenoma carries potential for life-threatening hemorrhage. A review of 108 cases of benign liver tumors reported since 1964 revealed 38 cases where sufficient pathologic data allowed an unequivocal differential diagnosis. Angiograms and radionuclide scans in these cases were correlated with the pathologic diagnosis. Focal nodular hyperplasia was characterized by hypervascular, sometimes multiple hepatic masses with dense, tortuous neovessels which occasionally showed a septated stain in a granular capillary phase corresponding to fibrous septa identified on gross pathology. One-third of these lesions captured sulfur colloid on radionuclide scans indicating Kupffer cell activity. Liver cell adenoma had a broad spectrum of angiographic findings ranging from completely avascular to hypervascular, with or without accompanying adjacent hematoma. All cases of adenoma had clear defects on liver scan reflecting their total lack of Kupffer cells. The findings of the review were applied to eight cases in which accurate radiologic differentiation could be made in seven on the basis of a combination of angiography and radionuclide scans.