Endocrine Abstracts

Objetive: The aim of our study is to asses the validity of ultrasound patterns proposed by the ATA and malignancy risk in the cytological diagnosis classified by the Bethesda System.

Methods: Prospective study including all thyroid nodules (with no previous cytological results), assessed in our center from July/2016 to June/2017. We classified nodules in ATA sonographic risk patterns and follow-up its fine needle aspiration (FNA) recommendations. The statistical study has been carried out with the statistical package SPSS 20.0

Results: We evaluated 402 thyroid nodules. 160 were selected by ATA criteria to citologycal diagnosis. These correspond to 144 patients (80.2% women, mean age 52.8 years). Mean TSH was 1.82 (0.37–6.96) and 28.8% patients presented positive autoinmunity (antitiroglobulin and/or antiperoxidase antibodies). The mean size nodules was 2.8±1.2 cm, with those with lower ultrasound risk of malignancy being higher (3.2 vs 2.1 cm, P 0.02). The frequency distribution in the different sonographic risk categories were: High risk 16.3%, Intermediate risk 10.6%, Low risk 50%, and Very low risk 18.1%. The 5% of the nodules could not be classified in any of the previous patterns. The malignancy rates (according to Bethesda System Classification as malignant o suspicious for malignancy) in each sonographic group was: High risk 61.5%, Intermediate risk 5.9%, Low risk 0% and Very low risk 0%. Thyroidectomy was performed in 42 patients, 27 of them (64%) were thyroid carcinomas. The overall malignancy, including the histology in those patients surgically removed, correlates with the ultrasound data (P>0,001): 80.7% in High risk, 11% in Intermediate risk, 3.75% in Low risk and 0% in those with Very low risk. In non-classifiable nodules, malignancy was observed in 12.5%.

Conclusions: Our prospective results supports sonographic risk patterns of thyroid nodules and FNA recommendation proposed by ATA 2015 guidelines. We have found a highly correlation between each sonographic pattern and likelihood of malignancy, both in cytology and surgical histology.