Evaluation of Incidental Thyroid Nodules on Neck CT and Their Clinical Significance

Abstract

Background: Incidental thyroid nodules are commonly detected on neck CT performed for non-thyroid indications. Although most are benign, some may represent clinically significant thyroid disease. Aim: To evaluate the prevalence, CT characteristics, and clinical significance of incidental thyroid nodules and their correlation with subsequent ultrasonographic, cytological, and histopathological findings. Materials and Methods: A prospective observational study was conducted over 18 months (January 2025–June 2026) in a tertiary care teaching hospital in India. A total of 600 adult patients undergoing contrast-enhanced neck CT for non-thyroid indications were evaluated. Nodule characteristics were assessed on CT, and selected patients underwent thyroid ultrasonography, fine-needle aspiration cytology, and histopathological evaluation. Results: Incidental thyroid nodules were identified in 138 of 600 patients (23.0%). The mean nodule diameter was 14.2 ± 8.6 mm, and 31 patients (22.5%) showed suspicious CT characteristics. Ultrasonography was performed in 96 (69.6%) patients and FNAC in 42 (43.8%) of these. Cytology was benign in 27 (64.3%), indeterminate in 8 (19.0%), suspicious in 3 (7.1%), and malignant in 4 (9.5%). Histopathology confirmed papillary thyroid carcinoma in 6 and follicular thyroid carcinoma in 1 patient. Overall, clinically significant thyroid pathology was identified in 10 patients (7.2%). Nodules ≥15 mm and those with suspicious CT features were significantly associated with clinically significant pathology (p<0.001). Conclusion: Incidental thyroid nodules are common on neck CT, but only a minority demonstrate clinically significant pathology. Nodule size and suspicious CT characteristics may help identify patients requiring further evaluation. A structured, risk-based approach can facilitate detection of significant thyroid disease while limiting unnecessary investigation.

Keywords: incidental thyroid nodule; neck computed tomography; thyroid incidentaloma; thyroid malignancy; thyroid carcinoma; multidetector CT; thyroid ultrasonography; fine-needle aspiration