Cholestatic features in focal nodular hyperplasia of the liver.

Twenty specimens of focal nodular hyperplasia were studied with special attention to the histological features of chronic cholestasis (grouped under the headings of cholestasis, cholate-stasis and signs of ductular reabsorption). In all specimens, evidence was found for one or more features of cholestasis and cholate-stasis. Signs of ductular reabsorption were less constant, and apparently varied according to the developmental stage of the lesion. The cholestatic features emphasize the bile secretory capacity of the lesional parenchyma, and are apparently due to the lack of real bile ducts in the portal tract equivalents of the lesional tissue. Evidence is presented that the "ductular component" in FNH is not due to proliferation of pre-existing ductules, but rather derives from ductular metaplasia of liver cell plates in zone 1 equivalents. This metaplastic development of a ductular network may serve the function of reabsorbing the biliary constituents produced by the lesional parenchyma, leading to periductular inflammation and progressive fibrosis, thus producing an equivalent of biliary fibrosis and biliary cirrhosis.