Abstract
BACKGROUND: Ultrasound guided fine-needle aspiration (USFNA) biopsy of thyroid nodules often gives a result of indeterminate pathology, placing thyroid specialists in difficult management situations. The aim of this study is to evaluate the incidence of malignancy in patients undergoing surgery and to correlate these results with the McGill Thyroid Nodule Score (MTNS). METHODS: We performed a retrospective study comparing USFNA results, MTNS and histopathology of patients undergoing thyroid surgery between 2010 and 2012. Pre-operative USFNA results were divided into three subgroups: benign, indeterminate and suspicious for/malignant. The indeterminate USFNA subgroup comprised of Bethesda type III (atypia of undetermined significance) and Bethesda type IV (follicular neoplasms, including Hurthle cell neoplasms) lesions. Post-operative histopathology was divided into benign or malignant groups. RESULTS: Of the 437 patient charts reviewed, 57.0% had an indeterminate USFNA biopsy. Within the indeterminate group, the malignancy rate was 39.8%. For indeterminate USFNA, the median MTNS was 7 (32% risk of malignancy) for benign nodules and 9 (63% risk of malignancy) for malignant nodules on post-operative histopathology (p < 0.05). CONCLUSION: The rate of malignancy in operated patients with an indeterminate USFNA result was 39.8%. The MTNS can be of value to thyroid specialists in pre-operative decision-making when dealing with an indeterminate result of a thyroid nodule on USFNA.