Sonographic Features of Thyroidal Fatty Lesions in the Thyroid Gland: A Preliminary Study

To my knowledge, no previous study has evaluated the sonographic features of thyroidal fatty lesions. The present study aims to assess the features of thyroidal fatty lesions as seen on ultrasound images and to determine the frequency of such lesions.

From January 2013 to December 2014, a total of 940 patients underwent preoperative ultrasound and CT examinations of the neck before undergoing thyroid surgery. The criterion for the diagnosis of thyroidal fatty lesions was the presence of intraglandular fatty tissue on CT images, regardless of lesion size. One radiologist retrospectively analyzed all the ultrasound and CT images of these patients.

Of the 940 patients whose images were reviewed, 20 (2.1%) had thyroidal fatty lesions noted on neck CT and 17 of these 20 patients had thyroidal fatty lesions (mean of largest diameter, 6.3 mm; range, 4.8-9.2 mm) noted on ultrasound. The 20 involved sites included the right lobe (n = 11), the left lobe (n = 9), and the isthmus (n = 0). For 17 of these 20 cases (85%), continuity with the adjacent thyroid capsule or perithyroidal fatty tissue was seen on ultrasound or CT. All thyroidal fatty lesions showed hyperechogenicity, no calcification, no posterior shadowing or enhancement, and an ovoid shape, and most thyroidal fatty lesions had inhomogeneous echogenicity and a smooth margin.

On ultrasound images, thyroidal fatty lesions characteristically appear as ovoid inhomogeneously hyperechoic thyroid nodules with no calcification, no posterior shadowing or enhancement, a smooth margin, and continuity with the adjacent thyroid capsule or perithyroidal fatty tissue.