[Focal nodular hyperplasia-like lesion of the liver associated with thorotrast liver disease--report of a case].

A 66-year-old man with Thorotrast liver disease underwent a partial hepatectomy for a small tumor of the liver, which was demonstrated by digital subtraction angiography. The resected specimen was grossly a sharply circumscribed, gray-yellow nodule, 7.5 mm in diameter. Microscopically, the nodule was an ill-defined hepatic cell mass, which was divided by fine fibrous septa irregularly and incompletely. Central veins and Glisson's capsules were not observed inside the nodule. Bile duct proliferation and infiltration of lymphocytes were found in the fibrous septa. There were Thorotrast depositions within the fibrous tissues around the nodule. Because a typical fibrous boundary and central scar were not found, we have termed this condition a focal nodular hyperplasia-like lesion. A relationship between focal nodular, hyperplasia as a precancerous state and Thorotrast liver disease was suggested.