Role of Preoperative Cellular Aspirate Expression Level of MicroRNAs in Diagnosis of Thyroid Cancer in Solitary Thyroid Nodule.

Objectives: Evaluation of the ability of the expression levels of microRNAs (Mir-) 146, 221, and 222 in the fine needle aspirate (FNA) of solitary thyroid nodules (STNs) to identify malignant aspirates. Patients and Methods: 58 thyroid patients underwent clinical assessment, and preoperative ultrasound grading according to ACR-Thyroid Imaging Reporting and Data System (ACR-TIRADS). The FNA was used for cytological examination according to the Bethesda System to report thyroid cytopathology and estimate the expression of microRNA levels using the quantitative reverse-transcriptase PCR. Patients underwent surgical excision, and the excised specimens were examined pathologically.Results: Pathological examination defined 24 malignant and 34 benign specimens. ACR-TIRADS defined 6 as highly, 9 moderately suspicious, 13 as mildly suspicious, and 30 nodules as benign or not suspicious nodules. FNA cytology defined 13 malignant, 7 suspicious aspirates for malignancy, and 15 aspirates as benign, while 5 aspirates were diagnosed as suspicious for follicular neoplasm, and 18 aspirates were of undetermined significance. The expression levels of Mir-146 and 222 were higher by 3.49 and 1.97 folds in malignant than benign aspirates, while Mir-221 levels were lower in malignant than benign aspirates by 4.04-folds. Statistical analyses defined expression levels of Mir-146 and -221 as the highly significant identifiers and the combined ACR-TIRADS and Mir-222 as diagnostic combinations for malignancy.Conclusion: microRNAs expression levels in thyroid nodule aspirate outperformed the preoperative US or FNAC for discriminating malignant nodules. Combined estimated expression levels of Mir-146 and -221 with US grading and FNAC showed a higher probability of detecting malignancy.