DETECTION OF ALBUMIN MESSENGER-RNA IN HEPATIC AND EXTRAHEPATIC NEOPLASMS - A MARKER OF HEPATOCELLULAR DIFFERENTIATION

Albumin is a ubiquitous protein Synthesized only by hepatocytes. Detec tion of albumin messenger RNA (mRNA) in neoplastic and non-neoplastic tissues using in situ hybridization may be useful in demonstrating hep atocellular differentiation. We investigated the presence of albumin m RNA by in situ hybridization in 69 hepatic and 29 extrahepatic tumors to determine its sensitivity and specificity for hepatocellular differ entiation. Albumin mRNA was detected in 22 of 23 hepatocellular carcin omas (96%); air hepatoblastomas, hepatocellular adenomas, and focal no dular hyperplasias; and within the hepatoid areas of an extrahepatic m alignant mixed germ cell tumor. All other hepatic and extrahepatic tum ors were negative for albumin mRNA. The staining was intense in focal nodular hyperplasias, weak in hepatocellular adenomas, and variable in hepatocellular carcinomas and hepatoblastomas. Non neoplastic, noncir rhotic liver was present in 50 cases; all were positive for albumin mR NA with variable staining, which was usually more intense than in the neoplasms. A zonal pattern of staining was present in 49 (98%) of thes e, with more intense staining within acinar zone I and least in zone 3 . This study shows that albumin inRNA is a specific marker of hepatoce llular differentiation but may be present in extrahepatic germ cell tu mors with hepatoid features. For primary hepatocellular carcinomas, in situ hybridization for albumin mRNA is a useful adjunct diagnostic me thod.