Navigating a Giant Thyroglossal cyst: A Compelling Case Study

Abstract

Thyroglossal duct cysts are congenital neck cysts, formed as a result of the failure of the thyroglossal duct to involute during embryogenesis. We present a case of a 55- year-old male who presented with a history of a large anterior neck mass measuring 11 x 8.5 cm. The mass was long standing and the patient presented to us 30 years after noticing it due to dysphagia and change in voice. A clinical diagnosis of TGDC was made based on clinical history, fine-needle aspiration biopsy and radiographic findings. The patient was treated with Sistrunk’s procedure. No recurrence and post-operative morbidity was noted on a 3 year follow-up. Sistrunk’s procedure with dissection of the posterior hyoid space is the standard of care with time-tested outcomes.

Introduction

Thyroglossal duct cysts (TGDCs) are one of the most prevalent congenital anomalies of the neck, making up for around 70% of all such anomalies. The thyroid gland, a vital endocrine organ, starts developing in the fourth week of gestation, emerging from the endodermal layer located in the developing floor of the pharynx. It descends caudally from the foramen cecum and positions beneath the thyroid cartilage at the end of the seventh week of gestation [1]. This developmental process underscores the intricate embryological origins of the thyroid gland, paving the way for understanding various anomalies associated with its development. The thyroglossal duct, an epithelial remnant, forms a link between the thyroid gland and the foramen cecum in the phases of embryonic development. Ordinarily, it undergoes involution by the tenth gestational week. However, if involution fails, it can lead to the development of cysts, sinuses, or fistulas along its course [2]. TGDCs normally appear as painless, midline neck masses which move with deglutition or when the tongue is protruded [3]. TGDCs usually measure between 1.5 and 2.5 cm, although there have been instances of larger cysts [1]. While generally benign, there is the risk of infection or malignant transformation.

The initial appearance, diagnosis, and management of TGDCs demonstrate major variations, and understanding these distinctions is necessary for appropriate clinical management. The case report documents a large TGDC in a 59-year-old male, who presented with a midline swelling in the neck, accompanied by dysphagia and hoarseness of voice. The clinical presentation, diagnostic workup, and subsequent surgery are discussed, highlighting the importance of thorough evaluation and individualised treatment planning in patients with thyroglossal duct cysts.

Case Report

A 55-year-old visited the Out-Patient Department of Head and Neck Services at Shanku’s Medicity Hospital, with a history of a large anterior neck mass that had been present for 30 years. The swelling was initially small and gradually progressed to attain the present size. He reported no pain during deglutition or palpation. Over the past two weeks, he started expressing concerns about issues with dysphagia and hoarseness in his voice. There was no history of radiation exposure or personal/familial history of thyroid cancer and no prior record of hypo or hyperthyroidism. There were no significant anomalies in his medical and surgical history. Habit history revealed active smoking amounting to 20 pack-years.

On examination, there was a large visible neck mass (Fig. 1), measuring 8.5 × 11 cm, extending to the mandible superiorly. It demonstrated limited mobility during deglutition and was non-tender, with no associated palpable cervical lymphadenopathy. The examination of the thyroid proved challenging due to the sizeable mass that was impeding the gland. The remainder of the examination yielded no significant findings. Differential diagnosis involved a thyroglossal duct cyst, thyroid malignancy, multinodular goitre, dermoid cyst, lymphadenopathy, and lipoma. A USG-guided fine needle aspiration biopsy was conducted, yielding negative results for malignancy, indicating a benign cystic lesion.

Fig. 1.

A) Pre-operative frontal view; B) Pre-operative lateral view; C) Pre-operative representative axial CT cut; D) Pre-operative sagittal CT

Diagnostic Assessment

The remainder of the clinical examination, upper airway endoscopy, and laboratory results were within the normal range. A computed tomography (CT) scan was carried out, showing a well-defined cystic lesion that extended from the infrahyoid neck region to the Manubrium sterni. The lesion measured 8.3 cm axially, 10.8 cm anteroposteriorly, and 10.8 cm craniocaudally, and did not exhibit contrast enhancement. The anterior thyroid lamina displayed a slight widening. A clinical diagnosis of a TGDC was established through an assessment of history, clinical findings, and radiographic evidence.

Surgical Procedure

A horizontal neck crease incision was made 3 cm above the sternal region Bilateral subplatysmal flap was raised in the neck. Bilateral Sternocleidomastoid (SCM) was identified. SCM was delineated from the internal jugular vein (IJV) and carotid arteries. Common carotid and thyroid were subsequently identified. The trachea was exposed after anteriorly incising strap muscles. A plane was cleaved between the trachea and thyroglossal cyst with gentle dissection. Laterally a plane was created between the common carotid thyroid and thyroglossal cyst. Blunt dissection was carried out to reach the thyroid cartilage and pharynx. The hyoid was identified superiorly. This was followed by meticulous blunt dissection around the cyst taking care not to rupture it. The thyroglossal tract was identified and the central portion of the body of the hyoid bone was resected along with the tissue along the tract (Sistrunk’s procedure). The specimen was delivered in toto and sent for histopathological examination which confirmed the diagnosis of TGDC. Fig. 2 illustrates key steps of the surgical procedure. At a 3-year follow-up, there was no evidence of recurrence or fistula formation. Skin overlying the neck was normal in appearance with a minimal scar along the neck crease. The patient had no difficulty in speech and deglutition.

Fig. 2.

A) Intraoperative after elevation of flap; B) Intraoperative bed after resection; C) Resected specimen with tract and central body of hyoid; D) Post-operative closure

Discussion

TGDC are the most prevalent form of congenital neck cysts, contributing to roughly 70% of documented cases. Although typically observed in paediatric patients, almost a third of cases have been identified in adults [4]. Thyroglossal duct cysts present as masses in the anterior neck, which results from the incomplete involution of the thyroglossal duct during embryonic development. They are conventionally located inferior and in proximity to the hyoid bone. They are generally asymptomatic central neck masses; however, inflammation may result in tenderness. The paper outlines an unusually large long-standing TGDC with a greater than average diameter in a male adult who experienced dysphagia and hoarseness, successfully treated using Sistrunk’s procedure. To our knowledge, there are 11 literature reports concerning unusually large TGDCs. The majority of those cases presented with symptoms including dysphagia, hoarseness, stridor, mild pain, drooling, and discomfort [5].

There are several instances of unusual TGDC in literature. Shaari et al. documented a case that included a large TGDC, which was eroding the thyroid cartilage and encroaching upon the pre-epiglottic space [6]. An uncommon case of a significant large TGDC (measuring 5 × 4.5 × 2.5 cm), in a neonate was reported by Fang et al. The cyst led to airway compression and breathing difficulties in the neonate [7]. It is pertinent to note that a large TGDC diversifies the spectrum of potential diagnoses. The differential diagnosis of TGDC encompasses dermoid and epidermoid cysts, lymphatic malformations, branchial cleft cysts, goitre, pyriform sinus fistulas, abscesses, thymic cysts, laryngocele, primary tumours, and lymph node metastasis [8]. Carcinoma can develop in approximately 1% of thyroglossal duct cysts, predominantly presenting as papillary carcinoma [9]. Thyroglossal duct cyst carcinomas usually range from 1 to 5.5 cm in size with the largest recorded carcinoma measuring 1.3 × 6 × 4.9 cm. Thyroglossal duct cysts show up on CT as thin-walled hypoattenuating masses, while TGDC carcinomas indicate increased wall nodularity, calcifications, and solid components within the cyst. The identification of calcifications can be considered a more specific marker for carcinoma when compared to solid debris, which may additionally be found in infected TGDCs [10]. In a series involving 685 cases, the cysts ranged in size from 0.2 to 8.5 cm, with mean measurements of 2.6 cm [1]. The mean diameter of thyroglossal duct cysts in adult patients was greater than in paediatric patients (2.8 cm and 2.1 cm, respectively). This suggests that smaller cysts tend to be more prevalent and make up the majority of the cases. On a literature review, there are a few notable reports of large TGDC. El-Ayman et al. reported a case involving a giant thyroglossal duct cyst, measuring 9.2 × 7.6 cm upon physical examination, in an 85-year-old male patient who was experiencing a slow, progressive increase in the size of the mass since the age of 20 [11]. Baisakhiya reported a case involving a 65-year-old male with a huge, multilobular thyroglossal duct cyst, measuring 11 × 9 cm upon physical examination [12]. Ramalingam documented a case in an adult presenting with a cystic neck tumour measuring 8 × 7 cm upon physical examination [8]. A sizeable thyroglossal duct cyst in a 55-year-old male, appearing as a middle mediastinal mass without any neck abnormalities was reported by Alavi and Gharabaghi [13]. This remains the only reported case of a substantial mediastinal thyroglossal duct cyst so far. Significantly, all these patients surpassed the usual age of presentation for a thyroglossal duct cyst, facilitating the anticipated progressive development of the mass, ultimately resulting in its manifestation as a huge cyst.

Conclusion

Thyroglossal duct cysts usually appear as clearly defined lesions in the anterior neck area, with sizes commonly ranging between 1.5 and 2.4 cm, though cases of larger cysts have been noted. Although larger cysts are unlikely to directly relate to severe symptoms, their size can complicate the task of making a differential diagnosis and thorough excision and pose airway challenges. It is imperative to rule out carcinoma with imaging and biopsy before surgery. Sistrunk’s procedure involves the excision of the cyst and dissection of the posterior hyoid space and is considered as the standard of care for such cases [14].

Author Contributions

The content of the manuscript has been checked and approved by the co-authors.

Funding

No funding was received to assist with the preparation of this manuscript.

Data Availability/Code Availability

Not applicable.

Declarations

Ethics Approval and Consent to Participate

The study was approved by the institutional research ethics committee (SMC IRB:579614) and performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki.

Informed Consent

Informed written consent was taken from the patient for the procedure in the patient’s own language.

Consent for Publication

Consent for reproduction of images and documenting the case for publication was also taken as part of the same consent from the patient and the relatives as part of a standard proforma. Patients signed informed consent regarding publishing their data and photographs.

Conflict of Interest

All authors have no conflicts of interest to declare.

Competing Interests

The authors have no competing interests to declare that are relevant to the content of this article.