Fibrolamellar carcinoma of the liver: the malignant counterpart of focal nodular hyperplasia with oncocytic change.

A case of fibrolamellar carcinoma (FLC) in a noncirrhotic liver of a 20-year-old man is described. Gross features and the presence, among the tumor cells, of bile ducts, of thick-walled blood vessels and nerves, and, ultrastructurally, of myofibroblast-like cells are the most significant findings, suggesting that FLC is the malignant counterpart of focal nodular hyperplasia with oncocytic change. Histochemical and immunohistochemical methods demonstrate the presence inside the oncocytic tumor cells of copper, copper-binding protein, and alpha 1 antitrypsin. The pathogenesis and the significance of these findings then are discussed and related to the restricted capacity of oncocytic cells to fulfill normal cellular function.