Risk of malignancy in patients with follicular neoplasm: predictive value of clinical and ultrasonographic features.

OBJECTIVE To identify clinical and ultrasonographic features that may help in predicting malignant tumors in patients with a diagnosis of follicular neoplasm on findings from fine-needle aspiration cytology (FNAC) because FNAC diagnosis of follicular neoplasm does not differentiate a benign tumor from a malignant tumor. DESIGN Prospective study of 98 patients having a diagnosis of follicular neoplasm on FNAC. SETTING Tertiary cancer referral center. PATIENTS Ninety-eight patients with thyroid nodules diagnosed by FNAC as being a follicular neoplasm. INTERVENTIONS Ultrasonography was performed in each patient, and microcalcifications, echo structure, and echogenicity of the nodules were assessed. All patients underwent surgery. MAIN OUTCOME MEASURES Sensitivity, specificity, positive predictive value, and negative predictive value of ultrasonographic features. RESULTS Thyroid cancer was diagnosed in 26 patients (27%). Ultrasonographic features (eg, a solid echo structure, microcalcifications, and a hypoechoic pattern) were predictive for malignant neoplasms. The variable associated with the highest sensitivity was the presence of a solid nodule (88.5%), and the variable associated with the highest specificity was the presence of microcalcifications (94.4%). The combination of the 3 ultrasonographic features (solid echo, hypoechoic pattern, and microcalcifications) resulted in a sensitivity of 95.0% and a specificity of 98.6%. Older age, male sex, solitary nodule, and larger nodule size were not predictive for malignant neoplasms in patients with follicular neoplasm cytologic findings. CONCLUSIONS We confirmed that the best compromise between the risk of missing carcinomas and the need for reducing unnecessary surgical procedures would consist of submitting to surgery those nodules presenting a solid echo structure, microcalcifications, or a hypoechoic pattern. Low-risk patients may be observed closely if they are willing to accept a small risk of cancer and if they appreciate the need for a close clinical follow-up.