Incidental Thyroid Nodules: Incidence, Evaluation, and Outcome

To examine patients with incidentally discovered thyroid nodules (IDTNs) with a focus on identification, evaluation, surgical intervention, and rates of malignancy.

Case series with chart review.

Tertiary care medical center.

A total of 1408 patients were identified by cross-referencing thyroid diagnosis codes with ultrasound (US) codes between July 2008 and June 2009. Information regarding demographics, follow-up, and outcomes was extracted from the medical record.

A total of 249 patients with IDTNs were identified. Most were discovered on computed tomography (CT) scans (59.8%); the most common indication for obtaining imaging was for evaluation of an unrelated malignancy (26.9%). Malignant IDTNs were identified on 23.8% of positron emission tomography/CT scans and 6.8% of CT scans. Initial evaluation of IDTNs was performed by US in 62.2% and by US with fine-needle aspiration (FNA) in 36.1% of patients. The most common pathology on FNA of IDTNs was benign follicular nodule (64.1%) followed by papillary thyroid cancer (PTC; 13.5%); however, 31.7% of all cytology indicated suspicion for malignancy. Fifty-five patients (22.1%) were treated surgically. On final surgical pathology, 33 malignancies were present, of which 28 were PTC. The overall malignancy rate for incidental thyroid nodules was 13.3%.

We identified a malignancy of at least 13.3% in IDTNs, reaffirming that IDTNs should undergo thorough workup.