Sonographic Features of Diffuse Hashimoto Thyroiditis: Determining Sensitivity of Features and Predictors of Malignancy

Abstract

Objective The objective of this study was to determine the sensitivity and accuracy of five sonographic features of Hashimoto thyroiditis (HT) in histologically confirmed cases. In addition, to determine if sonographic features can serve as a predictor of underlying malignancy. Methods A cohort of 101 patients who underwent thyroidectomy for malignancy or other clinical conditions with histologically confirmed HT and a pre-operative thyroid ultrasound examination were included. A retrospective analysis of sonographic features and radiology reports was conducted and comparative statistical analysis completed. Results Among the cohort of 101 patients, 84% demonstrated sonographic evidence of HT. The following features were used for the identification of HT: Diffuse hypoechoic echogenicity, parenchymal heterogeneity, hypoechoic micronodularity, echogenic septations, and hypervascularity. There was a female predominance (9:1) with an average age of 50 years. Among the studied sonographic features of HT, parenchymal heterogeneity was the most sensitive (88.2%) and hypervascularity was the least sensitive (17.7%). Approximately 44% of the study cohort had malignancy; papillary thyroid carcinoma was by far the most common, accounting for 89% of all malignancies. Hypoechoic micronodularity was the feature with the greatest positive predictive value (PPV) for malignancy. Nodal metastasis was less common in patients with sonographically evident HT. Conclusion HT is the most common cause of hypothyroidism in iodine sufficient areas of the world. Parenchymal heterogeneity and diffuse hypoechogenicity were the most sensitive sonographic features of HT. Hypoechoic micronodularity demonstrated the greatest PPV for malignancy.