Improving Malignancy Prediction in AUS/FLUS Pediatric Thyroid Nodules with the Aid of Ultrasound

The standard workup of thyroid nodules concerning for malignancy includes fine-needle aspiration (FNA). In 2015, the American Thyroid Association (ATA) guidelines for the management of pediatric thyroid nodules recommended that all nodules with a Bethesda III cytology undergo surgical resection.

To correlate a Bethesda III cytology with histologic and clinical outcomes to determine the relevance of the ATA recommendations, and to evaluate whether Thyroid Imaging Reporting and Data System (TI-RADS) scoring could identify Bethesda III nodules at a lower risk of malignancy.

A retrospective chart review of patients who had undergone thyroid nodule FNA from 2008 to 2018 was performed. Malignancy rates were determined for each Bethesda category. The reference standard was histopathology or 2-year follow-up of imaging outcomes for nonoperative cases. Ultrasound exams of Bethesda III nodules were reviewed and TI-RADS scores assigned.

A total of 143 FNA samples from 128 patients were identified. The mean age was 14.9 years (range 7-22). Twenty-two (15%) of the FNA samples were Bethesda III; the malignancy rate was 38%. A TI-RADS score was assigned in 20 of the 22 Bethesda III nodules. ROC analysis found an optimal cut-off for malignancy prediction of ≥7 points (risk category TR5). The negative predictive value was 85.7% (95% CI 35.9-99.6) and the positive predictive value was 83.3% (95% CI 57.2-98.2).

Although, at baseline, thyroid nodules with a Bethesda III classification carry a moderate risk of malignancy in the pediatric population, TI-RADS scoring can identify nodules with a lower risk within this group. If validated by larger studies, this can inform decision making and reduce unneeded surgery.