ARGYROPHILIC NUCLEOLAR ORGANIZER REGIONS IN PROLIFERATIVE LESIONS OF THE THYROID-GLAND

OBJECTIVE: To analyze various argyrophilic nucleolar organizer regions (AgNOR) parameters in proliferative lesions of the thyroid gland and to determine to what extent these parameters are influenced by the typ e of lesion or malignancy. STUDY DESIGN: AgNORs were studied by light microscopy with the help of a semiautomated image analysis system in t he normal thyroid gland (n=6), nodular hyperplasia (n=12), thyroid hyp erfunction (n=6), follicular adenoma (n=21), oxyphilic adenoma (n=10), follicular carcinoma (n=10), oxyphilic carcinoma (n=9), papillary ade nocarcinoma (n=14), and giant (n=6) and small cell anaplastic carcinom a (n=4). The investigated parameters included the number and area of A gNOR dots, the number of separate AgNOR locations, the ratio of the Ag NOR dot area to the nuclear area and the area of single AgNOR dots. RE SULTS: The number and area of AgNOR dots were low in all the lesions, with the exception of giant cell anaplastic carcinoma. The number of s eparate AgNOR locations wits the lowest in oxyphilic cell tumors and m edium in papillary adenocarcinoma, while in all other lesions and norm al thyroid it had higher values. The ratio of AgNOR area to the nuclea r area and the area of single dots were similar in proliferative lesio ns and normal thyroid. In all proliferative lesions and in normal thyr oid, there was a significant positive correlation (P less than or equa l to.0001) between the area or number of AgNOR dots on the one hand an d nuclear area on the other. CONCLUSION: The results indicate that in thyroid proliferative lesions, AgNOR values, particularly the number o f separate AgNOR locations, correlate with the type of lesion but not with malignancy. Very typical are single clusters of dots within nucle i in oxyphilic tumors, malignant and benign, and in papillary adenocar cinomas, more or less often accompanied by single dots.