How to combine ultrasound and cytological information in decision making about thyroid nodules

The purpose of this study was to evaluate the role of sonographic-cytological correlation in determining which nodules should be reaspirated to reduce the false-negative rate of fine-needle aspiration biopsy (FNAB). A retrospective cohort study was performed on a database of 568 patients with 672 focal thyroid nodules. An independent two-sample t-test was used to compare the risk of malignancy according to clinical factors. We evaluated the risk stratification of malignancy according to US groupings and cytological results. Additionally, we calculated the false-negative rate of FNAB and investigated the cytological results of repeat aspiration. The malignancy rate (92.2-98.5%) was high in thyroid nodules designated "malignant" or "suspicious for papillary carcinoma" on FNAB, regardless of US features. In contrast, when focal thyroid nodules had "benign" readings on FNAB, the malignancy rate was lower for the "probably benign" US features (2.9%) than for the suspicious nodules (56.6%). The false-negative rate of FNAB was 5.8%. Repeat aspiration revealed "suspicious for malignancy" or "malignancy" results in 15 (93.8%) of 16 thyroid cancers with "benign" results on initial aspirate. This study demonstrated repeat FNAB should be performed on focal thyroid nodules with suspicious US features even when initial FNAB results are benign.