Endocrine Abstracts

Introduction: Most studies which scrutinized the ATA 2015 thyroid nodule guidelines were performed retrospectively, in tertiary centers of excellence and in Western populations. We sought to prospectively apply these guidelines, under ‘real world’ conditions and in an eastern Mediterranean population.

Methods: Thyroid nodules were prospectively and independently assessed by two experienced sonographers and classified as per the guidelines. Only nodules that underwent USS-guided FNA were included for this study. Descriptive statistics are provided. Statistical analysis was performed using the chi-square test.

Results: 214 nodules in 175 consecutively assessed patients were included (mean age 54.3 years; females 84.6%). They were sonographically classified as per the ATA guidelines as very low, low, intermediate and high risk in 7 (3.3%), 110 (51.4%), 65 (30.4%) and 32 (15%) nodules, respectively. Their cytological classification was Thy1, Thy2, Thy3a, Thy3f, Thy4 and Thy5 in 10 (4.7%), 169 (79%), 15 (7%), 9 (4.2%), 5 (2.3%) and 6 (2.8%). The correlation between the sonographic and cytological classification of nodules was excellent (P<0.0001); for example, Thy2 appearances were observed in 7/7 (100%), 100/110 (90.9%), 52/65 (80%) and 10/32 (31.2%) of nodules sonographically classified as very low, low, intermediate or high risk, respectively. Histology was available for 47 nodules; 16/47 (34%) were malignant. The risk of malignancy was 1/1 (100%), 2/17 (11.8%), 2/12 (16.7%) and 11/17 (64.7%) with very low, low, intermediate and high risk USS appearances, respectively (P=0.002). The two patients with low risk USS features who were diagnosed with malignancy included one patient with a nodule at 5 cm and another with incidental mPTC not in the nodule which was aspirated. The risk of malignancy was 0/1, 3/18 (16.7%), 1/10 (10%), 2/7 (28.6%), 4/5 (80%) and 6/6 (100%) with Thy1, Thy2, Thy3a, Thy3f, Thy4 and Thy5 cytological appearances, respectively (P=0.001). The three patients with Thy2 cytology with malignancy on histology included a 49-year-old lady with a positive family history and a large cystic nodule with very dark/viscous material aspirated, a 25 year-old with intermediate risk nodule but rapid growth associated with discomfort and a 66-year-old lady with a low risk nodule with a diameter up to 3.7 cm.

Discussion: Apart from the relatively higher rate of malignancy observed in Thy2 cytology results, our prospective data are similar to those provided at the guidelines, indicating the utility of the guidelines in routine secondary care practice and in different populations. Notwithstanding, clinical acumen remains of paramount importance when applying the guidelines.