Overexpression of the nucleolar organizer regions (NORs) in the thyroid follicular tumours. Comparison of the cytological and histopathological examinations.

The aim of the study was to determine the usefulness of the expression of argyrophilic nucleolar organizer region proteins (AgNORs) as a marker of malignancy degree in thyroid follicular tumours. The study used the postoperative material of thyroid glands and cytologic material obtained with fine needle aspiration biopsy. Follicular adenoma, carcinoma and struma nodosa hyperplastica-type changes were analysed. The comparison of the AgNOR parameters examined revealed statistically significant differences between the groups of follicular carcinoma and follicular adenoma, follicular carcinoma and nodular goitre, and between adenoma and nodular goitre. However, the "overlapping" of value ranges was observed between the groups of follicular carcinoma and adenoma, as well as follicular adenoma and nodular goitre. This referred particularly to atypical adenoma parameters found within a non-diagnostic range. No differences were observed in the counts of AgNOR dots between histologic and cytologic material obtained with fine needle aspiration biopsy.