Malignancy rates and initial management of Thy3 thyroid nodules in a district general hospital: The 'Reading' experience

Background Ultrasound-guided fine-needle aspiration cytology is the gold standard for investigating thyroid nodules. Stratifying the Thy3 thyroid nodule risk of malignancy is essential for clinical decision-making. According to the Royal College of Pathologists Guidance (2016), the rate of malignancy for Thy3a is 5-15% and for Thy3f 15-30%. Our aim was to investigate the malignancy rate and the initial management of Thy3 nodules in our institution. Methods A retrospective review was undertaken of 115 patients with Thy3 cytology results from thyroid fine-needle aspirations performed between January 2015 and June 2020 at a single centre. A total of 90 out of 115 patients underwent surgery. Results Of the 90 patients, we had a 40% malignant rate (36/90). Specifically, 14 of 34 (41.1%) Thy3a and 22 of 56 (39.2%) Thy3f nodules were malignant. Of the malignant lesions, 52.7% (19/36) were follicular thyroid carcinoma. 58.8% (10/17) of male patients and 35.6% (26/73) of female patients had a malignant histology. Eighteen patients eventually needed a completion thyroidectomy. Conclusion Compared with national data, we showed a higher risk of malignancy in Thy3 nodules in our centre. Our study should encourage other centres to audit their own data. We propose setting up a national Thy3 registry as a basis to promote research in improving preoperative diagnosis of indeterminate thyroid nodules.