Intralobular thyroid regeneration: ultrasound signs

IntroductionUltrasound scan (ultrasound) allows the determination of the specific pattern of the thyroid gland changes in Hashimoto thyroiditis (HT) [1-4,etc.]. These ultrasound findings include local lesions, which are also known as micronodules or pseudonodules by specialists [5, 6]. These areas in the gland are moderately or significantly hypoechoic and are spherical or ellipsoidal in shape. They predominantly have a clear edge and lack microcalcifications. Moreover, they are located separately or in groups and are usually several millimeters in size [5, 7, 8].These pseudonodules of the thyroid gland are aggregations of lymphocytes formed due to the replacement of follicular tissue in the lobules and/or lymphoid germinal centers [5, 9, 10]. They clearly differ from thyroid nodules; however, according to some authors, they require needle biopsy for discriminatory diagnosis against microcarcinomas [11]. Despite this precaution, experts assess this focal and diffuse process as highly sensitive and highly specific in Hashimoto thyroiditis ultrasound/sonoelastography diagnosis [7, 10].In recent review articles and guidelines for ultrasound of the thyroid gland, this pseudonodulation process is merely considered as a symptom of Hashimoto thyroiditis, without explaining variants of its changes [12, 13]. Meanwhile, there are facts that significantly complement our knowledge about the pseudonodules of the thyroid gland, which reveal the patterns and essence of this process. The regeneration process is among them [14].