Malignancy risk of initially benign thyroid nodules: validation with various Thyroid Imaging Reporting and Data System guidelines

Some authors have found little or no diagnostic benefit from repeated biopsy of benign thyroid nodules. However, to our knowledge, integration of Thyroid Imaging Reporting and Data System (TIRADS) guidelines with one biopsy for sufficient benign thyroid nodule diagnosis has not been previously described. We investigated malignancy rate and probability by using various malignancy stratification systems in initially biopsy-proven benign nodules and sought to determine their clinical relevance in management of benign thyroid nodules. This retrospective study collected 6762 thyroid nodules from 6493 consecutive patients who underwent biopsy between January 2013 and December 2013. The initial biopsy with ≥1 year of follow-up was used as the gold standard for benign diagnosis. For our study purpose, we analyzed 2747 (57.0%, 2747 of 4822, 532 women, 2111 men; 229 malignant and 2518 benign) thyroid nodules diagnosed by initial biopsy with 28.2 ± 9.1 (range, 12–41) months of follow-up. We calculated the malignancy probability of thyroid nodules by using various malignancy risk stratification systems. The overall calculated thyroid malignancy rate was 8.3% (229 of 2747). Initially biopsy-proven benign nodules exhibited a ≤3.0% malignancy probability when assessed as “low suspicion” by Korean-TIRADS (K-TIRADS), “low suspicion” by the ATA guideline, and “very probably benign” by the French TIRADS guideline and gave a score of ≤3 by the web-based TIRADS. When initially biopsy-proven benign nodules exhibit a “low suspicion” US pattern and low malignancy probability, as stratified by various TIRADS guidelines, imaging surveillance instead of second biopsy is warranted. • One biopsy is sufficient for initially biopsy-proven benign nodules. • Repetitive biopsy is necessary for imaging–pathology mismatched nodules. • Scoring risk stratification permits personalized management.