Extension of Multinodular Goiter to the Parapharyngeal Space – a Case Report

Abstract

parapharyngeal space can have a mass of thyroid origin following metastasis from the thyroid or ectopic thyroid tissue. The extension of multinodular goiter into the parapharyngeal space is rare. A 54-year-old female presented with a 5-month history of neck mass and dyspnea. On examination, a large mass was seen on the right side of the neck which was bulging into the right parapharngeal. In the sonography, a large 50 × 57 mm cyst seen at the upper end of the right lobe of the thyroid. Computed tomography (CT) identified a 46 × 56 mm lesion medial to the right carotid sheath with a mass effect on the parapharyngeal space from the posterolateral aspect and appeared to be an exophytic cystic nodule arising from the upper pole of the right thyroidal lobe. The patient underwent total thyroidectomy, and the final pathology of multinodular goiter was reported. The spread of masses of the thyroid origin to the parapharyngeal space should be considered one of the differential diagnoses of these space masses.

Introduction

Thyroid enlargement may extend beyond the normal borders of the thyroid bed [1]. The most common form of extension is caudal, which extends into the anterior or posterior mediastinum. In contrast, the cranial or lateral expansion on either side of the pharynx is less frequent [2]. Rarely, goiters can enlarge and spread upward to appear as a parapharyngeal mass. According to the literature, the first case of multinodular goiter spread to the parapharyngeal space was described by Clark ST et al. [3]. In this article, we present the second case of this presentation. A 54-year-old female who has a multinodular goiter of thyroid extending to the parapharygeal space is presented in this case report.

Case Report

A 54-year-old woman presented with a five-month history of a painless, rapidly growing mass in the thyroid area on the right side of the neck with a “hot potato” voice and dyspnea during sleep and after activity. She did not report dysphagia, odynophagia, or B-type symptoms (fever, night sweats, or weight loss). Her medical history included hypertension and there was no personal or family history of thyroid disease or malignancy. On examination, a large mass was visible and palpable on the right side of the neck without signs of inflammation or tenderness. Video laryngoscopy revealed a mass bulging on the right side of parapharngeal area, with intact vocal fold movement and no further abnormalities (Fig. 1a,b). The physical activity resulted in an audible respiratory sound known as stertor.

Fig. 1.

Physical examination (a) Mass on the right side of the neck. (b) Mass bulging into pharyngeal space

The patient was clinically and biochemically euthyroid (Thyroid-Stimulating Hormone 2 mIU/ml). All other blood tests were normal. Sonography revealed that the thyroid lobes are larger than normal and it contains two solid cystic nodules measuring 32 × 32 mm and 23 × 18 mm. Also, a large 50 × 57 mm cyst is seen at the upper end of the right lobe that extends into the lower region of the right parotid gland. The above cyst contains internal septa. No pathological cervical lymphadenopathy was observed.

Computed tomography (CT) identified a 46 mm × 56 mm lesion that was medially located on the right carotid sheath and exerted a mass effect on the parapharyngeal space from its posterolateral aspect. This lesion appeared to be an exophytic cystic nodule arising from the upper pole of the right thyroidal lobe. Multiple hypo-dense nodules were seen in both thyroidal lobes, with a mass effect on the trachea from its anterolateral aspect (Fig. 2a-c). Ultrasound-guided fine-needle aspiration (FNA) cytology was non-diagnostic.

Fig. 2.

Neck CT scan demonstrated a large, cystic lesion from the thyroid pushing the larynx to the left and extending into parapharyngeal space. (a) Axial. (b) Coronal. (c) Sagittal

Due to rapidly worsening respiratory distress, the patient underwent total thyroidectomy surgery after awake fiberoptic intubation was performed following induction of general anesthesia. The procedure was performed using a transcervical approach, and the thyroid gland was removed. Adequate exposure revealed the superior extension of the right hemi-thyroid and continuity with the parapharyngeal mass (Fig. 3a-c). Surgery was performed to preserve two recurrent laryngeal nerves and four parathyroid. The examination showed that she was successfully treated with a good voice which was confirmed by a laryngoscopy. The patient was kept nothing by mouth (NPO) for 24 h following the operation then fluids and a soft diet were started, which did not have any problem in swallowing. Also, the patient was extubated and admitted to the ICU for 48 h to be closely monitored for airway edema, bleeding, and respiratory problems. Fortunately, the patient did not experience any complications and was discharged after three days with a normal calcium level. After five months of operation, the patient had no problems.

Fig. 3.

Surgical view (a, b) Mass with extension to the parapharyngeal space. (C) After total thyroidectomy

Macroscopically, it consists of a thyroid weighing 159 g. Cut sections of the right lobe show a 5.5 cm cyst containing a blood clot, while cut sections of other parts show nodular surfaces containing brownish and gelatinous materials. Microscopically, sections show thyroid tissue composed of different-sized follicles with inflammatory cell infiltration & hemosiderin deposit (Fig. 4). There is no evidence of malignancy in this specimen. Histopathologic findings confirmed the diagnosis of multinodular goiter.

Fig. 4.

Histologic section of the lesion (a, b) Thyroid follicles of various sizes that are rich in colloid and have no evidence of malignancy

Discussion

Multinodular goiter, a diffuse enlargement of the thyroid gland, can also occur in iodine-deficient areas. Other causes are Hashimoto’s thyroiditis, Graves’ disease, thyroiditis, and thyroid cancer. The proximity of the thyroid gland to the esophagus, trachea, and larynx, thyroid goiter can cause various pressure symptoms such as dysphagia, hoarseness, and shortness of breath [1]. Treatment of thyroid goiter is often medical, however, if the goiter is left untreated or if treatment is ineffective or delayed, it can cause excessive enlargement of the gland, requiring surgery [4]. The caudal extension is more common, growing toward the anterior or posterior mediastinum. However, growth in the cephalic or lateral direction, towards both sides of the pharynx is less common [2].

Superior extension of the thyroid gland is uncommon due to anatomic compartments created by the fascial plates in the neck, and goiters tend to grow toward the mediastinum, resulting in substernal or retrosternal goiters, and symptoms associated with airway compression and/ or esophagus creates [5, 6]. It is rare that the goiter grows upwards and spreads and appears as a parapharyngeal mass as in our case.

The fascia mentioned above creates complex but continuous spaces that include the thyroid gland, parathyroid glands, trachea, and larynx which explains the anatomical basis for the extension of the enlarged thyroid toward the retropharynx and parapharynx [1, 2]. Therefore, despite its rarity, clinicians should be aware of this possibility when evaluating a parapharyngeal space mass. The parapharyngeal space (PPS) is a complex anatomical region in the neck. This space is like an inverted pyramid, whose base starts in the skull floor and its apex ends in alignment with the large horn of the hyoid bone [3]. PSS masses are rare and account for only 0.5% of head and neck neoplasms [7]. Most of these masses have a salivary origin and are benign [3]. Spread from thyroid tissue to PPS occurs very rarely. In this study, we describe a case of multinodular goiter (MNG) that extended to the PPS.

In our case, the pathologist reported mass contained a blood clot, which could explain the recent start of the patient’s symptoms, following bleeding in the cyst, which led to progressive enlargement of the thyroid gland and extended to the parapharyngeal space. One of the causes of respiratory distress in thyroid disease is the rapidly progressive pressure on the trachea caused by spontaneous bleeding inside the thyroid [8]. Venous bleeding is thought to be the most likely cause of bleeding in goiter [9].

Adenomatous goiter is more fragile than normal thyroid and is often caused by increased vascular flow and lack of true capsule. These features increase the possibility of bleeding in blunt trauma [10] or after fine needle aspiration biopsy [11]. However, the mechanism underlying spontaneous thyroid bleeding is unclear.

Our knowledge is the second reported case in the literature of a multinodular thyroid goiter with an extension to PPS. The first case was a 35-year-old man with a 3-year history of a painless and slowly enlarging right-sided oropharyngeal mass. After evaluation, it was determined that the mass originated from the thyroid and had extended into the parapharyngeal space. Multinodular goiter pathology was reported [3]. Also, one case was described by Cetik et al. [7]. The patient was a 22-year-old woman who had complained of a painless mass in her neck and dysphagia and hoarseness for two years. After the necessary evaluations, it was determined that the tumor is a mass originating from the upper pole of the right lobe of the thyroid, which has extended to the lower part of the parapharyngeal space. The final pathology showed a follicular variant of papillary thyroid carcinoma.

So, one of the manifestations of huge benign or malignant thyroid masses can be extended to adjacent neck spaces such as the parapharyngeal space, and these masses should be considered as a differential diagnosis of masses in this space.

Conclusion

Our case demonstrates in the patient’s multinodular thyroid goiter, it is essential, to consider the possibility of thyroid gland extension to adjacent structures and spaces, and we must take these cases into account as a differential diagnosis of a parapharyngeal mass.

Funding Statement

No funding has been taken from any sources.

Declarations

Conflict of Interest

None.

Ethical Statement

This manuscript was written by the Code of Ethics of the World Medical Association (Helsinki Declaration) and it was sanctioned by the Ethics Committee of GUMS (IR.GUMS.REC.1402.175). I confirmed a patient’s anonymity. I have obtained informed consent from the participant presented in the study.