Promising results of studies on different neoplasms, by means of morphometric analysis of argyrophilic nucleolar organizer regions (AgNORs), known as proliferative activity marker, made us undertake an attempt to evaluate of proliferative activity in Hürthle Cell Tumors using the same technique. 78 cases including 20 Hürthle Cell Carcinomas (HCC), 32 Hürthle Cell Adenomas (HCA) and 26 hyperplastic nodules with Hürthle Cell Metaplasia (HCM), diagnosed in the Department of Clinical Pathology, Medical Academy of Bialystok in the years 1990-2000, were subjected to analysis. For visualization of the NORs we used the D. Ploton et al. technique. Mean AgNOR count and NORDS (NOR distribution score--the percentage of nuclei with at least 5 argyrophilic granules) were estimated in each case in 100 randomly chosen nuclei. Non-parametric Mann-Whitney U-test was applied to determine statistically significant differences.
Results: Mean AgNoRs counts and NORDS values were 5.1 and 52%, 3.4 and 26%, 2.5 and 7% in HCC, HCA and HCM respectively. Statistically significant differences were found between AgNORs counts in carcinomas and adenomas (p<0.01), HCCs and HCMs (p<0.005) and betwveen NORDS in all groups (p<0.001).