A. R. Marcadis1, M. Rodriguez1, S. Liu1, B. Wang1, J. I. Lew1 1University Of Miami Miller School Of Medicine,Division Of Endocrine Surgery,Miami, FL, USA
Introduction: With the advent of better imaging technology and its widespread utilization in the clinic setting, incidental thyroid nodules are often discovered while evaluating patients for unrelated disease. If the risk of underlying thyroid malignancy in such incidental nodules is common, further evaluation is required. However, if thyroid cancers are exceedingly rare in such incidentally discovered thyroid nodules, further costly evaluations can be avoided. The purpose of this study is to compare the rate of malignancy in incidentally-discovered thyroid nodules (IDTN) by imaging to nonincidentally-discovered thyroid nodules (NDTN) in surgical patients.
Methods: A retrospective review of prospectively collected data of 1370 patients who underwent thyroidectomy at a single institution was performed. Before surgical resection, all patients underwent surgeon-performed ultrasound (SUS) and fine-needle aspiration (FNA). Patients who had IDTN by imaging studies for unrelated reasons (n=536) and patients who had NDTN (n=834) were further stratified according to age, gender, FNA results, SUS characteristics and final pathology. Rates of malignancy in IDTN and NDTN were calculated and statistical significance was determined by two-tailed Z-test.
Results: Of 1370 patients, 536 presented with IDTN by imaging and 306 (57%) were found to have malignancy on final pathology. Of patients with IDTN found to have malignancy, 92% (n=283) had papillary thyroid cancer, 5% (n=14) medullary thyroid cancer, and 3% (n=9) follicular thyroid cancer. Of the patients with NDTN, 401 (48%) were found to have malignancy following surgery with 44% (n=366) papillary thyroid cancer (PTC), 2.2% (n=18) medullary thyroid cancer, 2% (n=14) follicular thyroid cancer, and <1% anaplastic thyroid cancer (n=3). The rate of PTC on final pathology for IDTN was statistically higher than the rate of PTC found in NDTN (p<0.05). Patients with IDTN had statistically higher rates of microcalcifications (34%), hypoechogenicity (60%), and irregular borders (35%) by SUS compared to patients with NDTN (p<0.05). There was also a significantly higher rate of patients with IDTN who had all three SUS features together (14%) compared to patients with NDTN (10%) (p<0.05). There was no significant difference in percentage of malignant FNA results between patients with IDTN and NDTN.
Conclusion: For IDTN, malignancy rates may be higher than expected in surgical patients. Furthermore, certain characteristics of SUS may help predict malignancy in IDTN. The high rate of malignancy suggests that total thyroidectomy by an experienced surgeon should be strongly considered when managing such patients with IDTN.