Risk of Malignancy in Patients With Follicular Neoplasm

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.