Non-Utility of Thyroid Nodule FNAs Not Recommended by ACR TI-RADS

Purpose: The ACR Thyroid Imaging Reporting and Data Systems (TI-RADS) is an evidence- and consensus-based guideline system designed to facilitate thyroid nodule management. Referring physician acceptance, however, is variable. We aimed to assess the results of thyroid nodule fine needle aspiration (FNA) on nodules which did not meet TI-RADS criteria for tissue sampling.

Methods/Materials: We retrospectively evaluated outcomes of all 198 thyroid FNAs performed over a one-year period on 160 patients at our large academic health system. Follow-up cytology, surgical pathology, genetic testing, and imaging results were reviewed.

Results: Of all 198 sampled nodules, 162 (81.8%) were benign, 14 (7.1%) showed follicular lesion of undetermined significance (FLUS) and/or atypia of undetermined significance (AUS), 8 (4.0%) were malignant, and 14 (7.1%) were non-diagnostic. Of the 198 total FNAs, 30 (15.1%) were not recommended by TI-RADS criteria. Of these, 25/30 (83.3%) were benign on initial sampling, 1 (3.3%) showed AUS, and 4 (13.3%) were non-diagnostic. The AUS nodule showed benign Hurthle cell adenoma on subsequent surgical pathology. On follow-up of the non-diagnostic samplings, the nodules were either sonographically stable (1/4; 25%) or benign by subsequent surgical pathology (3/4; 75%). As such, no malignancy was detected in any nodule which did not meet TI-RADS criteria to be sampled.

Conclusions: In the setting of thyroid nodules not meeting TI-RADS criteria for sampling, clinician referral for FNA is not uncommon despite malignancy being exceptionally rare in these cases. Even in cases in which TI-RADS criteria does advise biopsy, malignancy is still uncommon. Efforts to improve referring physician education, optimize referral appropriateness, and institute collaborative care pathways are warranted to minimize unnecessary invasive procedures and most judiciously utilize procedure-related resources.