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A Case of Ectopic Thyroid at the Suprasternal Notch with Cervical Compressive Discomfort
Int J Thyroidol 2022;15(2):144-147
Published online November 30, 2022;  https://doi.org/10.11106/ijt.2022.15.2.144
© 2022 Korean Thyroid Association.

Sang-Wook Park1, Changhyeon Lee1, Seongjun Won1,2 and Jung Je Park1,2

Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine1, Institute of Health Sciences, Gyeongsang National University2, Jinju, Korea
Correspondence to: Jung Je Park, MD, PhD, Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, 79 Gangnam-ro, Jinju 52727, Korea
Tel: 82-55-750-8177, Fax: 82-55-759-0613, E-mail: capetown@gnu.ac.kr
Received October 2, 2022; Accepted November 10, 2022.
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Ectopic thyroid is an anomaly that arises during embryogenesis of the thyroid gland. It is rare and can cause symptoms such as throat discomfort, dysphagia, and dyspnea depending on its size and location. This case is important because ectopic thyroid presenting as a suprasternal notch mass with a suspicion of thyroid malignancy is rare, and highlights the management decision and its consequence.
Keywords : Ectopic thyroid, Thyroid dysgenesis, Suprasternal notch mass
Introduction

Ectopic thyroid is an unusual form of thyroid dysgenesis resulting from abnormal migration of the thyroid gland. Due to abnormal migration, the ectopic thyroid gland can appear at the suprasternal notch, heart, and esophagus. Ectopic thyroid with symptoms or a suspicion of malignancy should be managed surgically. We present a patient with an isolated suprasternal mass that was confirmed to be ectopic thyroid, and we also provide a literature review.

Case Report

A 69-year-old woman visited our clinic with cervical compressive discomfort. On physical examination, there was no palpable mass such as a lesion at the anterior neck, and there was no definite abnormal finding in the larynx upon laryngoscopic examination. She had once undergone radiofrequency ablation of a thyroid nodule on the right side at another hospital. To investigate the cervical compressive discomfort and follow-up the thyroid nodule, we performed neck ultrasonography. There was a C5 nodular lesion measuring 1.5×1.0×0.6 cm with punctate echogenic foci and a heterogeneous echoic mass with an irregular surface at the suprasternal notch (Fig. 1). Following fine needle aspiration of the thyroid nodule, cytological evaluation revealed atypical cells of undermined significance. We performed neck enhanced computed tomography (CT) to obscure adjacent anatomical structures of the thyroid gland and suprasternal notch mass. There was a relatively highly attenuated mass at the suprasternal notch with a well-bounded circumference, and a hypo-attenuated thyroid nodular lesion was found (Fig. 2). We performed diagnostic right unilateral thyroidectomy with mass excision under general anesthesia. Preoperative serum thyroid hormone, thyroid-stimulating hormone, and calcium levels were within the normal limits. The suprasternal notch mass was encapsulated and well dissected without any connection to the thyroid gland (Fig. 3). It was confirmed to a nodular goiter and diagnosed as ectopic thyroid tissue (Fig. 4). The right thyroid lobe was confirmed to be a nodular goiter. The patient was discharged 6 days postoperatively and has remained free of disease without cervical compressive discomfort for 3 months after surgery.

Fig. 1. Representative sonographic image of the neck. A heterogeneous echoic mass measuring 2.24×1.23 cm with an irregular surface.

Fig. 2. Representative neck computed tomography images. A well-circumscribed irregular mass measuring 2.6 cm at the suprasternal notch (yellow arrow) and a thyroid nodule with low attenuation (black arrow-head) (A: axial, B: coronal).

Fig. 3. Operative findings. (A) A round well-circumscribed mass at the suprasternal notch without any connection to the thyroid gland. (B) A firm mass measuring 2.6×2 cm was removed.

Fig. 4. Representative pathologic section. A section of the suprasternal mass showing follicles of various sizes surrounded by flattened epithelium and containing colloid (Hematoxylin & Eosin staining, original magnification ×200).
Discussion

Ectopic thyroid is a rare form of thyroid dysgenesis and defined as thyroid tissue not located at an orthotropic site.1) It is rare, and its prevalence is approximately 1 per 100,000-300,000 persons.2) It arises mainly along the descending path of the normal thyroid gland during the gestational period and is usually found at the base of the tongue.3) Ectopic thyroid at rare locations, including the trachea, mediastinum, heart, and esophagus, has been reported.4)

The primitive thyroid arises from the pharyngeal base between the first and second pharyngeal pouches.5) As an endodermal proliferation of the pharyngeal base, it forms a diverticulum. Around the fifth week of gestation, the thyroid diverticulum migrates caudally along the midline and passes through the hyoid bone and laryngeal cartilage.1) During this migration, the hollow thyroid diverticulum solidifies with follicular elements.6) At the seventh week of gestation, the thyroid finally locates in the anterior neck, while the fourth and fifth pharyngeal pouches contact and conglomerate at the thyroid with filling of para-follicular elements. If the primitive thyroid gland moves lower than the orthotropic location, an ectopic thyroid gland can appear at the suprasternal notch, mediastinum, and heart.7)

Ectopic thyroid is usually asymptomatic and often found incidentally on radiological examinations.6) If the ectopic thyroid grows to a considerable size, it can cause various symptoms depending on its location.2) Lingual thyroid can cause throat discomfort, hoarseness, and dysphagia. Cervical ectopic thyroid can be a palpable mass and even cause dyspnea if it presses on the airway.4)

Neck ultrasonography, CT, and radionuclide thyroid scanning are useful to diagnose a cervical midline mass suspected to be ectopic thyroid.4) Neck ultrasonography is noninvasive and rapid, and can provide information about the properties of a mass, such as its size, cystic changes, and vascularity.8) Ectopic thyroid has similar sonographic features as the normal thyroid gland with the exception of its shape and size. Variable echotexture of ectopic thyroid has been reported. CT can clarify the size and extension of the mass, and the relationship between ectopic thyroid tissue and adjacent structures.3) Ectopic thyroid is a vessel-rich tissue and is therefore slightly attenuated on CT.9,10) CT can help to determine a resection range before surgery.10) Radionuclide thyroid scanning is a noninvasive diagnostic modality and useful to identify all the sites of ectopic thyroid tissue.6,11)

Patients who are asymptomatic and have normal thyroid function do not require treatment, but patients with any symptoms or complications should be treated in a customized manner with consideration of the size and location of ectopic thyroid, and the thyroid function level.11) Patients with hypothyroidism can be treated with levothyroxine. Levothyroxine suppresses thyroid-stimulating hormone secretion and can decrease the size of ectopic thyroid.3,6) Ectopic thyroid that continues to cause symptoms despite medical treatment or is suspected to be malignant should be managed surgically. Before surgery, it is necessary to confirm the presence of a normal thyroid gland. The ectopic thyroid gland may be the only gland that makes thyroid hormones if there is no orthotropic thyroid gland.9) Without confirmation of the presence of a normal thyroid gland, excision of ectopic thyroid may lead to permanent hypothyroidism.6)

In our case, the suprasternal mass compressed the anterior neck, which led to compressive discomfort, and was suspected to be a metastasis of thyroid malignancy; therefore, surgical resection was necessary for diagnosis and treatment. If a mass at the suprasternal site is clinically found with symptoms, ectopic thyroid should be considered, and treatment should be decided based on the mass properties, thyroid function, whether a normal thyroid gland exists, and patient age.

Conflicts of Interest

No potential conflict of interest relevant to this article was reported.

References
  1. Noussios G, Anagnostis P, Goulis DG, Lappas D, Natsis K. Ectopic thyroid tissue: anatomical, clinical, and surgical implications of a rare entity. Eur J Endocrinol 2011;165(3):375-82.
    Pubmed CrossRef
  2. Mussak EN, Kacker A. Surgical and medical management of midline ectopic thyroid. Otolaryngol Head Neck Surg 2007;136(6):870-2.
    Pubmed CrossRef
  3. Cho IK, Lee SJ, Chung PS. A case of dual ectopic thyroid mistaken as thyroglossal duct cyst. J Korean Thyroid Assoc 2009;2(1):62-6.
  4. Kumar Choudhury B, Kaimal Saikia U, Sarma D, Saikia M, Dutta Choudhury S, Barua S, et al. Dual ectopic thyroid with normally located thyroid: a case report. J Thyroid Res 2011;2011:159703.
    Pubmed KoreaMed CrossRef
  5. Guerra G, Cinelli M, Mesolella M, Tafuri D, Rocca A, Amato B, et al. Morphological, diagnostic and surgical features of ectopic thyroid gland: a review of literature. Int J Surg 2014;12 Suppl 1:S3-11.
    Pubmed CrossRef
  6. Lee BJ, Lee TW, Park SH, Aiba H, Kojima C, Kyogoku Y. Nuclear magnetic resonance study of complexes between CRP and its 22- and 28-base-pair operators. J Biochem 1995;117(2):239-43.
    Pubmed CrossRef
  7. Kousta E, Konstantinidis K, Michalakis C, Vorias M, Sambalis G, Georgiou M, et al. Ectopic thyroid tissue in the lower neck with a coexisting normally located multinodular goiter and brief literature review. Hormones (Athens) 2005;4(4):231-4.
    Pubmed CrossRef
  8. Ryu GH, Chang YW, Lee DH, Choi DL, Kwon GH, Yang SB. Sonographic features of dual ectopic thyroid: report of two cases. J Korean Soc Ultrasound Med 2011;30(2):121-31.
  9. Wang J, Fang J. Ectopic thyroid mass in the left lateral neck and anterior mediastinum: a case report. J Med Case Rep 2014;8:351.
    Pubmed KoreaMed CrossRef
  10. Sohail AA, Shahabuddin S, Siddiqui MI. Ectopic thyroid mass separately present in mediastinum and not a retrosternal extension: a report of two cases. Case Rep Surg 2019;2019:3821767.
    Pubmed KoreaMed CrossRef
  11. Kim YH, Han HJ, Jung D, Moon JH. A case of mediastinal ectopic thyroid cyst inducing severe airway compression. Korean J Otorhinolaryngol-Head Neck Surg 2016;59(12):860-4.
    CrossRef


November 2022, 15 (2)