Assessment of nucleolar organizer regions (NORs) in proliferative conditions of the liver.

To overcome the diagnostic dilemma in proliferative conditions of the liver which sometimes pose a problem to the working pathologist especially when the material is inadequate, a special staining technique (AgNOR) has been applied. By using this technique, nucleolar organizer regions were counted which determine the proliferative status of the cells. This prospective study included 65 cases of randomly selected liver core and fine needle aspiration biopsies. AgNOR staining was performed on formalin-fixed, paraffin-embedded tissue sections NOR dots were counted in 100 randomly selected hepatocytes at x100 oil immersion objective, and the mean count per cell was calculated for each case. Statistical analysis was done by using the Mann Whitney U test. AgNOR count results were later compared with the histologic diagnosis. The study revealed a gradual increase in mean AgNOR counts from normal liver through cirrhosis to hepatocellular carcinoma. The difference in NOR counts was significant in these three groups. The hepatocellular carcinomas were graded according to the Edmondson-Steiner histological grading system. The Grade I hepatocellular carcinomas show AgNOR counts ranging between 5-6/cell, a score which is much higher than in the normal liver, where it ranges between 1.2-2.0/cell. This technique can be used to assess the lesions where the distinction between normal liver and Grade I hepatocellular carcinoma is difficult with the use of routine methods. AgNOR counts in normal liver and chronic hepatitis cases were insignificant, but there was an appreciable difference between cases of chronic hepatitis, cirrhosis and hepatocellular carcinoma. In view of the results of this study, the AgNOR staining method is found to be a useful diagnostic tool to differentiate between normal liver, cirrhosis and hepatocellular carcinoma and also to precisely discriminate between cases of normal liver and Grade I hepatocellular carcinoma.