Evaluation of MIB-1 immunoreactivity and nucleolar organizer regions in nonneoplastic and neoplastic thyroid lesions

Epithelial hyperplastic lesions of the thyroid gland still pose many diagnostic problems, despite considerable progress in the diagnosis of thyroid disorders. Especially borderline lesions are difficult to differentiate. The aims of this study were to evaluate the diagnostic value and compare the number of AgNORs and MIB-1 expression in thyreocytes from various pathological thyroid changes with special emphasis on borderline lesions (hyperplastic nodule-adenoma-follicular carcinoma). Material included 83 sections from 72 thyroid glands (55 women, 17 men, and mean age 45). According to histological examination the sections were divided into 7 groups: parenchymal goiter, nodular goiter, follicular adenoma, follicular carcinoma, papillary carcinoma, oxyphilic carcinoma and anaplastic carcinoma. Statistical analysis of the results revealed a significant correlation between the values of the number of AgNORs or MIB-1 proliferation index and neoplasm malignancy grade as well as a correlation between the number of AgNORs and MIB-1 proliferation index. The results demonstrated that both the number of AgNORs and the proliferative activity marker MIB-1 may be an additional diagnostic criterion in differential diagnosis of borderline thyroid lesions (each feature separately, but better effects are obtained when considering both).