ACTA ENDOCRINOLOGICA (BUC)

Aim: We have undertaken an attempt to compare the application efficacy of the proliferative activity markers in the differential diagnosis of thyroid H?rthle cell tumors using the PCNA and Ki-67 labeling and AgNOR visualization techniques.\r\nMaterials and methods: The present work is a retrospective analysis of proliferative potential in 40 H?rthle cell tumors, on paraffin blocks: 10 H?rthle cell carcinomas (HCC), 16 H?rthle cell adenomas (HCA) and 14 hyperplastic nodules with H?rthle cell metaplasia (HCM). The evaluation of the mean number of nucleolar organizer regions (NORs) per nucleus and the proliferative index (PI-the percentage of PCNA and Ki-67 positive cells) was performed using staining silver impregnation method and antibodies against PCNA (clone PC 10) and Ki-67 (clone MIB-1) in LSAB detection Kit and visualization with DAB (diaminobenzidine). U-Mann-Whitney test was used for statistical analysis. The difference was considered significant for p<0.05.\r\nResults: The values of PI-PCNA, PI-Ki-67 as well as the mean AgNOR counts in nuclei were: 25.5, 12.8, and 5.0 in HCC; 7.6, 4.9, and 3.1 in HCA and respectively 5.1, 4.0 and 2.3 in HCM. Statistically significant differences were found in all the proliferative\r\nactivity markers between malignant and benign tumors: HCM: HCC (p<0.0001) and HCC: HCA (p<0.001). Indifferently of the examined markers and the method of quantification of the reaction, we did not found significant differences between hyperplastic nodules with H?rthle cell metaplasia and oncocytic adenomas (p< 0.07).\r\nConclusions: PI-PCNA, PI Ki-67 and mean AgNOR/ nucleus, used as markers for the appreciation of proliferative activity of oncocytic thyroid tumors (classified as adenomas, carcinomas and hyperplastic nodules with H?rthle cells), reflect differences between the studied thyroid lesions. Our results indicate the utility of these parameters in the differentiation of the benign oncocytic tumors from the malignant ones.

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