Sonographic Features of Nodular Hashimoto Thyroiditis Daniel Corey Oppenheimer, MD,* Ellen Giampoli, MD,† Simone Montoya, MD,* Swapnil Patel, MD,* and Vikram Dogra, MBBS‡ Objective: The aim of the study was to analyze the sonographic fea- tures of nodular Hashimoto thyroiditis (HT) in patients with diffuse background thyroiditis and normal background thyroid parenchyma. Subjects and Methods: Eighty-six patients who had fine-needle as- piration biopsy of 100 thyroid nodules confirmed to be HT and a thy- roid ultrasound within 1 year of the biopsy were included in the study. Retrospective analysis of several sonographic features of each nodule was then performed. Results: The mean age of patients with nodular HT was 53 years, 84% of which were female. Nodular HT occurred in a background of diffuse thyroiditis in 85% and in a homogeneous normal background in 15%. Ninety-three percent of nodules were completely solid and 7% of nodules were cystic and solid. Although the sonographic appear- ance of nodular HT was variable, the most common appearance was a solid (93/100) and hypoechoic nodule (44/100) with a thin hypoechoic halo (42/100) without calcifications (96/100). On color Doppler, 17% of nodules showed peripheral hypervascularity, 14% of nodules were diffusely hypervascular, 34% were iso vascular, 32% were hypovascular, and 3% were avascular. The sonographic appearance of nodular HT was not significantly different in patients with diffuse background thyroiditis compared with those without background thyroiditis. Conclusions: The sonographic appearance of nodular HT is variable, but the most common appearance is a solid sharply circumscribed hypoechoic nodule with thin hypoechoic halo without calcification. There was no significant difference in the appearance of nodular HT in patients with diffuse background thyroiditis compared with pa- tients with normal background thyroid parenchyma. Key Words: Hashimoto thyroiditis, chronic lymphocytic thyroiditis, fine needle aspiration (Ultrasound Quarterly 2016;32: 271–276) H ashimoto thyroiditis (HT), also known as chronic lym- phocytic thyroiditis, is an autoantibody-mediated thyroid disease, which results in gradual destruction of follicles within the thyroid gland. Hashimoto thyroiditis is the most common cause of hypothyroidism in the United States and typically re- sults in painless enlargement of the thyroid gland. 1 Classi- cally, the diagnosis is confirmed by demonstrating low serum T4 and high thyroid stimulating hormone (TSH) levels with the presence of autoantibodies to thyroglobulin and thyroid peroxidase. 2 However, the clinical and serological presentation is highly variable, and a significant subset of patients have ab- sent or low autoantibody levels. 3 The sensitivity and specificity for diagnosing HT improve when clinical and serologic as- sessments are combined with ultrasound examination, but the criterion standard for diagnosis remains fine-needle aspi- ration biopsy (FNA-B) and/or histologic analysis. 4 Sonographically, HT most commonly presents as a dif- fusely enlarged thyroid gland with coarsely heterogeneous paren- chymal echogenicity, echogenic septations, and micronodularity, usually with diffuse hyperemia—so called diffuse HT. 5 Less commonly, more discrete macronodules may occur within a background of diffuse HT or even within normal background thyroid parenchyma. 6 This pattern is known as nodular HT. The purpose of this study was to analyze the sonographic features of nodular HT. Subjects and Methods Subjects Patients at a single US medical center were included in this institutional review board–approved study. All patients underwent FNA-B of at least 1 focal thyroid nodule between January 2011 and June 2015 and a diagnostic thyroid ultra- sound within 1 year of the FNA-B. Pathologic Analysis Patients were included in the study if the FNA-B results were interpreted as HT or chronic lymphocytic thyroiditis. The cytology report was reviewed to ensure that the biopsied nodule was correctly located on ultrasound. Histology slides were re-examined on a selected basis. Sonographic Analysis Ultrasound images of patients with at least 1 nodule, which had FNA-B, were retrospectively reviewed by a single radiologist and a variety of predetermined sonographic features were analyzed (Figs. 1–8). Nodule dimensions were measured in 3 planes. The composition of the nodules was characterized as solid or solid and cystic. No purely cystic nodules were eval- uated. The solid noncalcified component of each nodule was evaluated for echogenicity relative to the adjacent thyroid pa- renchyma (hyperechoic, isoechoic, or hypoechoic). The echo- texture of the solid noncalcified component was interpreted as Received for publication December 29, 2015; accepted January 22, 2016. *From the Department of Imaging Sciences, University of Rochester Medi- cal Center; †Department of Pathology and Laboratory Medicine; and ‡Departments of Imaging Sciences, Biomedical Engineering and Urology, University of Rochester Medical Center, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, NY. The authors declare no conflict of interest. Address correspondence to Vikram S. Dogra, MD, Departments of Imaging Sciences, Biomedical Engineering and Urology, University of Rochester Medical Center, School of Medicine and Dentistry, 601 Elmwood Ave, Box 648, Rochester, NY 14642 (e‐mail: Vikram_Dogra@urmc.rochester.edu; Vikram.Dogra54@gmail.com). Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/RUQ.0000000000000228 Ultrasound Quarterly • Volume 32, Number 3, September 2016 www.ultrasound-quarterly.com 271 ORIGINAL RESEARCH Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.