Background: Fine needle aspiration (FNA) is used to diagnose thyroid nodules, but the follow-up of benign FNA is unclear. We sought to determine whether routine repeat FNAs after initial benign FNA reduces false negatives.
Methods: We identified 265 patients who had at least one benign FNA that either progressed to surgery or had at least one repeat FNA. We reviewed their ultrasonography, FNA cytology, and surgical pathology.
Results: Of 127 patients with initial benign FNA that had surgery, 13 had a malignancy, yielding a 10.2% false-negative rate. Of 22 patients who had surgery after at least two benign FNAs, one had a malignancy, yielding a 4.5% false-negative rate. Initially benign cytology (Bethesda II) was upgraded to a cytology requiring surgical intervention (Bethesda IV-VI) in 7 of 129 (5.4%) patients after two FNAs. Suspicious features on ultrasound, including size >4 cm, calcifications, or increased vascularity were found in 90% of patients with a false-negative FNA.
Conclusions: The overall false-negative rate of thyroid FNAs is 10.2%, which is reduced to 4.5% with a second benign FNA. Ninety percent of patients with a false-negative FNA had suspicious sonographic features. Reaspiration should be considered in patients with sonographically suspicious nodules.