Abundant expression of cytokeratin 7 in fibrolamellar carcinoma of the liver.

Two cases of fibrolamellar carcinoma of the liver, one with lymph node metastasis are reported. Using immunohistochemistry as well as one- and two-dimensional gel electrophoresis and Western blotting, tumour cells of both primary lesions and of the metastasis were found to express cytokeratin polypeptides 8 and 18 and, surprisingly, cytokeratin 7. A small number of cells also expressed cytokeratin 19. This is the first detailed analysis of the cytokeratin expression of fibrolamellar carcinoma, and is also the first to present biochemical evidence that, contrary to what has been suggested, hepatocellular carcinomas do not always preserve the pattern of cytokeratin expression of normal hepatocytes.