Ultrasonographic features associated with malignancy in cytologically indeterminate thyroid nodules

ContextThyroid nodules with indeterminate cytology usually are treated with surgery, but most are benign. Neck ultrasonography has varied results in predicting malignancy.ObjectiveTo evaluate the predictive value of ultrasonography and the frequency of malignancy in patients who had indeterminate thyroid nodules.DesignRetrospective study.SettingUniversity hospital.PatientsThere were 78 patients who had thyroid nodules that were diagnosed on cytology (fine needle aspiration) as a follicular lesion (atypia of undetermined significant) or follicular neoplasm. Ultrasonography was available in 69 patients (88%).Intervention and main outcome measuresDiagnostic fine needle aspiration (cytology), ultrasonography, and surgical pathology of thyroid nodules.ResultsFine needle aspiration was indeterminate in all patients, with follicular lesions in 60 patients (77%) and follicular neoplasm in 18 patients (23%). Ultrasonography showed micro calcification in 6 patients (9%), irregular border in 15 patients (22%), size ≥ 3 cm in 31 patients (45%), and hypoechogenicity in 43 patients (62%). Surgical pathology showed that the nodules were benign in 50 patients (64%) and malignant in 28 patients (36%).Malignancy was significantly associated with male sex (relative risk, 2.3), solid nodule structure (relative risk, 2.6), and irregular border (relative risk, 3.6). Compared with other ultrasonographic characteristics, irregular borders had the highest specificity (93%), positive predictive value (80%), and accuracy (78%) for malignancy.ConclusionsThe frequency of malignancy is high in indeterminate thyroid nodules. Based on the limited accuracy or predictive value of ultrasonographic risk factors, surgery is the treatment of choice for indeterminate thyroid nodules.