Zuckerkandl Tubercle of the Thyroid Gland: Correlations between Findings of Anatomic Dissections and CT Imaging

Abstract

Background and purpose: The Zuckerkandl tubercle is located at the posteromedial border of the thyroid lobe, and it may be confused with a neoplasm or other mass. This study was performed to clarify the position and morphologic characteristics of the Zuckerkandl tubercle by dissecting cadavers and to compare the findings with the corresponding CT images obtained in the same cadavers.

Materials and methods: One hundred thyroid lobes from 50 fresh cadavers were dissected for this study (20 males and 30 females; mean age at death, 77.3 ± 11.5 years). CT scans were obtained in 10 of the cadavers by using a 128-channel multidetector row CT scanner before dissection.

Results: The Zuckerkandl tubercle of the thyroid gland was observed in 83% of the specimens. It was mostly located at the posteromedial border of the thyroid lobe and within the middle two quarters (2nd and 3rd) of the thyroid lobe. The Zuckerkandl tubercle was classified into 3 types based on its direction of extension: posteromedial in 64% of the specimens, posteromedial and superior in 13%, and posteromedial and inferior in 6%. On axial CT, the Zuckerkandl tubercle was usually continuous with the posteromedial part of the thyroid lobe and extended posteromedially to the esophagus. The parts of the Zuckerkandl tubercle that protrude posteromedially and superiorly or posteromedially and inferiorly from the thyroid lobe appeared separated from the thyroid gland by a thin, low-density string on axial CT.

Conclusions: Zuckerkandl tubercles that protrude toward the posteromedial and superior or inferior direction could cause confusion due to their separation when performing diagnoses with CT images.

Fig 1.

Location of the ZT and its superior and inferior borders according to the thyroid lobe (A) and the level of the tracheal rings (B). CC indicates cricoid cartilage; TC, thyroid cartilage; Rt, right; Lt, left; Sup, superior; Inf, inferior.

Fig 2.

Types of ZTs based on the direction of extension: posteromedial (A), posteromedial and superior (B), and posteromedial and inferior (C). D, A specimen with an uneven ZT surface, which divides into 2 parts due to a deep groove (arrowhead) representing impressions of the blood vessels. Arrows indicate the ends of ZT extensions. Es indicates esophagus; PThG, parathyroid gland; Tr, trachea.

Fig 3.

Comparison of ZT on axial CT (A), cross-sectional (B), and histologic (C) images of the same specimen. The ZT (arrows) is continuous with the posterior part of the thyroid lobe, extends posteromedially toward the posterior end of the esophagus, and is compatible with the other areas of thyroid tissue in the microscopic finding. LB indicates lateral border of the thyroid lobe; Es, esophagus; ThG, thyroid gland; Tr, trachea.

Fig 4.

ZTs protruding posteromedially and superiorly (left side) and posteromedially and inferiorly (right side) in both thyroid lobes of the same cadaver, and their shapes on axial CT images at different levels. Arrowheads and arrows indicate the ZT and the slit between the ZT and the thyroid lobe, respectively. PThG indicates parathyroid gland.

Fig 5.

Comparison of clinically acquired axial CT images between the ZT appearing discontinuous from the thyroid gland and as a separate nodule or lymph node. A, Contrast-enhanced CT scan of a 33-year-old male patient who had undergone neck CT for work-up of lymphoma. There is a bulging structure (arrow) at the posterior aspect of the right thyroid lobe, and a fat plane between this structure and the thyroid lobe. The bulging structure protrudes toward the posterior and medial direction. The fat plane is not evident at the lower level of the CT image (B), which means that the bulging structure is a ZT protruding in the posteromedial and superior direction. C, Contrast-enhanced CT scan of a 65-year-old female patient who had hyperparathyroidism. An oval nodular lesion (arrowhead) separated from the thyroid gland with a fat plane is seen posterior to the right thyroid lobe and is protruding in the posterior and lateral direction. This nodule is suggested to be a parathyroid adenoma or hyperplasia in the delayed image of the parathyroid scan (D).