Predicting malignancy of thyroid nodule using EU-TIRADS ultrasound score in an area of iodine deficiency

Background: In iodine-deficient region, thyroid nodules (TN) are more frequent and the proportion of benign nodules is higher compared to areas with sufficient iodine intake. Objective The aim of this study was to assess factors associated to malignant TN specially the Eu-TIRADS ultrasound score in a Moroccan population with high prevalence of iodine deficiency. Methods: In a prospective cross-sectional study, we enrolled outpatients referred for TN with Fine Needle Aspiration Biopsy (FNAB) indication according to EU-TIRADS 2017 classification. Malignancy of TN was defined by histological results indicating a thyroid malignancy on thyroid micro-biopsy or after surgical resection if indicated. Results: 225 TN were enrolled. The median of the patients’ age was 54 (42.5 ; 62) years-old. The prevalence of malignant TN was 8.9%. Malignant TN were significantly smaller than non-malignant ones (p = 0.008) and sub-centimetric TN were more frequent in malignant TN (25% vs 1.5%; p < 0.001). On multivariate analysis, male gender (OR : 9.33 ; 95% CI 2.02 ; 43.01; p = 0,004) and EU-TIRADS 5 score (OR : 55.6 ; 95% CI 9.34 ; 327.91 ; p < 0.001) were independent factors associated with malignant TN. The EU-TIRADS 4 score was not associated to malignant TN. Conclusion Our data suggest a trend of over-diagnosing indolent thyroid cancer. The EU-TIRADS 4 score was not associated to TN malignancy. Considering clinical, accessory sonographic features and size threshold for FNAB in EU-TIRADS 4 score TN may refine the diagnosis performance of this score category in our population.