Does the presence of additional thyroid nodules on ultrasound alter the risk of malignancy in patients with a follicular neoplasm of the thyroid?

Background: Follicular neoplasms of the thyroid are associated with an approximately 20% risk of malignancy. We sought to determine whether the presence of additional thyroid nodules on preoperative ultrasound decreased the risk of malignancy in a patient with a follicular neoplasm. Methods: Between January 2000 and November 2006, 325 patients underwent thyroidectomy with a fine needle aspiration diagnosis of either follicular neoplasm, Hürthle cell neoplasm, or indeterminate (not including suspicious for papillary thyroid cancer). Records were reviewed retrospectively and statistical analysis was performed using SPSS (SPSS Corporation, Chicago, Ill). Results: The rate of malignancy in our patient population was 20% (23% in follicular neoplasm, 19% in Hürthle cell neoplasm, 9% in indeterminate). Overall, 57% of patients had multiple thyroid nodules on preoperative ultrasound. The risk of malignancy was lower in patients with greater than or equal to 1 additional nodule in comparison with those with a solitary nodule (16.6% vs 28.0%, P = .02). The risk of malignancy was lowest in those with 1-3 additional nodules in comparison with those with greater than or equal to 4 nodules (14.5% vs 21.7%, P = .04). Conclusions: The presence of additional thyroid nodules on preoperative ultrasound is associated with a lower risk of malignancy in a patient with a follicular neoplasm.