Fibrolamellar carcinoma: a review with focus on genetics and comparison to other malignant primary liver tumors

Fibrolamellar carcinoma is a rare primary malignant liver neoplasm that usually affects adolescents and young adults with no underlying liver disease. Morphologically, the tumor cells resemble oncocytic hepatocytes arranged in cords with a stroma of lamellated collagen fibers. Immunohistochemical studies have found that fibrolamellar carcinomas express markers associated with both biliary (CK7 and epithelial membrane antigen) and hepatocytic (heppar-1and glypican-3) differentiation, as well as markers associated with hepatic progenitor cells (CK19 and EpCAM) and stem cells (CD133 and CD44). Genetic studies show fewer alterations compared with classic hepatocellular carcinoma. Pooled data from comparative genomic hybridization studies show that fibrolamellar carcinomas have fewer and less frequent genomic alterations when compared with classic hepatocellular carcinoma, cholangiocarcinoma, and hepatoblastoma. Of the alterations seen in fibrolamellar carcinoma, the most frequent are gains in 1q and 8q (also frequently seen in other hepatic tumors) and loss of 18q. Fibrolamellar carcinoma also has less frequent methylation of tumor suppressor promoters compared with hepatocellular carcinoma and minimal alterations in mitochondrial DNA. Fibrolamellar carcinoma is associated with better survival than hepatocellular carcinoma and cholangiocarcinoma, presumably due to the young age of the patients and the lack of cirrhosis. These features make more aggressive surgical therapy possible. There is currently very little information on the effectiveness of chemotherapy for fibrolamellar carcinoma.