Method of detection of thyroid nodules: correlation with frequency of fine-needle aspiration and malignancy rate.

Background: Thyroid nodules are commonly found by screening, and the clinical implications are unclear.

Methods: We retrospectively studied 460 patients who were evaluated for thyroid nodules. Medical records were queried to determine how the nodules were detected. We compared the rates of fine needle aspiration (FNA) and malignancy between nodules detected clinically, incidentally on imaging, or by screening.

Results: Nodules were detected clinically in 184 patients (40%), incidentally in 121 patients (26%), and by screening in 155 patients (34%). The rates of FNA and malignancy were lower for patients with nodules detected by screening (28% and 1%, respectively), compared to patients with clinically apparent nodules (75% and 15%) and patients with incidental nodules (69% and 8% [P < .001]).

Conclusion: Thyroid nodules detected via screening has a lower rate of FNA and is less likely to be diagnosed as a malignancy compared to nodules detected clinically or incidentally on imaging. Thyroid ultrasound examinations should be reserved for nodules that are clinically apparent or to evaluate nodules found incidentally on imaging.