Diagnostic implications of albumin messenger RNA detection and cytokeratinpattern in benign hepatic lesions and biliary cystadenocarcinoma

Cytokeratin (CK) patterns and albumin messenger RNA (mRNA) are investigated in 24 patients with benign hepatic lesions (7 patients with focal nodular hyperplasia [FNH], 10 with hepatocellular adenomas [HA], 1 with biliary ham artoma, 4 with biliary cysts, 2 with cystadenomas) and in 8 patients with c ystadenocarcinoma, a rare liver malignancy. The lesions and surrounding tis sue of the hepatocytic components expressed CK 8 and 18 at immunohistochemi stry, whereas the biliary elements evidenced CK 8 and 18 and CK 7 and 19. T he albumin mRNA, as detected by in situ hybridization (ISH), revealed diffe rent distributions in the hepatocytes of FNH and HA. In the benign biliary lesions, the normal hepatocytes surrounding the tumors expressed albumin mR NA, whereas the biliary structures did not. Interestingly, in the cystadeno carcinomas, albumin mRNA was observed not only in the hepatocytes of residu al parenchyma, but also in neoplastic bile duct cells lining the carcinomat ous cysts; no signal was identified in the nonneoplastic biliary elements. This indicates that cystadenocarcinomas have a mixed biological phenotype a nd suggests they could arise either from pluripotent cells or from neoplast ic cells that reacquire epigenetic features. Our results suggest two possib le diagnostic applications for albumin ISH: on routine sections, it could r epresent an important tool for distinguishing between cystadenoma and cysta denocarcinoma; and on fine needle biopsy specimens, it could reduce uncerta inty between FNH and HA.