Background/Aims: To assess whether the presence of certain findings on thyroid ultrasonography (US) correctly diagnoses malignancy even when a fine-needle aspiration biopsy (FNAB) suggests a benign lesion. Methods: We reviewed the charts of 35 children and adolescents with a thyroid nodule who had had an US and a FNAB, and for whom final pathology was available. Results: The global accuracy of FNAB was 83%, with a sensitivity of 75% and a specificity of 94%. 14 FNABs suggested malignancy (40%), only 1 of which was a false positive (7%). By contrast, 5 of the 21 FNABs suggesting benign lesions were false negatives (24%). These 5 cases had US findings suggestive of malignancy. When FNAB suggested a benign lesion, US had a good sensitivity (80%) but a poor specificity and accuracy (50 and 57%, respectively); its negative predictive value was 90% and its positive predictive value 36%. Conclusions: US complements FNAB in the evaluation of thyroid nodules in children. A more aggressive approach is warranted in children with a thyroid nodule and a benign FNAB if US findings suggest malignancy.

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