Diagnostic Application of AgNORs Quantification and Ki67 In Different Thyroid Lesions

Purpose: We aimed to assess the utility of quantitative analysis of AgNORs and Ki67 labeling index (LI) in the differential diagnosis of different thyroid lesions. Material and Methods: This study included: 25 papillary carcinoma, 7 follicular carcinoma, 21 follicular adenoma and 27 nodular goiter. Using a semiautomatic image analysis system, AgNORs parameters were measured and calculated including: total area of AgNORs, mean AgNOR number in nuclei, nuclear area, mean area of AgNOR dots per each nucleus, percentage of central and marginal AgNOR dots, and the relative ratio of total area of AgNOR dots/ total area of nucleus. Ki67 immunostaining was performed and the LI was determined. Results: There was a significant difference between groups regarding total area of AgNORs, AgNOR number and percentage of marginal AgNOR dots. According to receiver operating characteristic curve, AgNORs number =2.91 and marginal AgNORs = 2.67 were useful cut off values above which follicular carcinoma can be diagnosed with 100% sensitivity, 79% specificity, 76% positive predictive value (PPV), 100% negative predictive value (NPV) and 85% diagnostic accuracy for both parameters. Mean Ki67 LI in our study was 14.12 ± 2.29, 61.42 ± 5.77, 34.90 ± 3.49 and 18.60±1.96 for papillary carcinoma, follicular carcinoma, follicular adenoma and nodular goiter respectively. Ki67 LI showed statistically significant difference between follicular carcinoma and follicular adenoma (p=0.026) and between papillary carcinoma and follicular adenoma (p=0.007). Conclusion: Quantification of AgNORs and Ki67 LI could be used as helpful ancillary methods in the differentiation between different thyroid lesions.