Incidental Thyroid Nodules Detected on Thoracic Contrast-Enhanced CT in the Pediatric Population: Prevalence and Outcomes

OBJECTIVE. The purpose of this study was to investigate the prevalence and outcomes of incidental thyroid nodules detected on thoracic contrast-enhanced CT (CECT) in the pediatric population. MATERIALS AND METHODS. We used our hospital information system to retrospectively identify all consecutive pediatric patients (< 21 years old) with newly detected thyroid nodules reported on thoracic CECT performed between January 2006 and January 2013. The study population was categorized into two groups: patients with (group 1) and without (group 2) an available follow-up thyroid ultrasound study. Two pediatric radiologists systematically reviewed the CT studies, available follow-up thyroid ultrasound studies, and outcomes of patients meeting the inclusion criteria. For patients without an available follow-up ultrasound study (group 2), the duration of clinical follow-up was also evaluated. If a biopsy was performed, the pathologic diagnosis was correlated with the imaging findings. RESULTS. The study population consisted of 35 thoracic CECT studies from 35 pediatric patients (18 females, 17 males; mean age, 13 +/- 6.2 [SD] years) who met the inclusion criteria. The prevalence of incidental thyroid nodules detected on thoracic CECT in our study population was 1.4% (35/2525 patients; 95% CI, 1-2%). Seventeen of the 35 (49%) patients (group 1) underwent follow-up thyroid ultrasound, six (17%) of whom ultimately underwent biopsy of the thyroid nodule for pathologic diagnosis. Among these six patients, two (33%) were found to have malignant thyroid nodules: papillary thyroid carcinoma and thyroid involvement by an underlying Burkitt lymphoma. Therefore, the prevalence of malignancy among incidentally detected thyroid nodules on thoracic CECT in pediatric patients in this study was 5.7% (2/35 patients; 95% CI, 2-18%). The remaining four of six patients (67%) had benign thyroid nodules. Eighteen of the 35 (51%) patients (group 2) had only clinical follow-up information (mean follow-up, 27.1 +/- 21.1 months); no neoplasm subsequently developed from incidentally detected thyroid nodules among this subset. CONCLUSION. Thyroid nodules detected incidentally on thoracic CECT are rare in pediatric patients. However, when thyroid nodules are present, ultrasound (with or without biopsy for pathologic evaluation) is an appropriate strategy because of the rare but real possibility of an underlying thyroid malignancy in the pediatric population.