Case Report
 

By Dr. Samah Khayat , Dr. Alaa Al-Juaid , Dr. Arif Khorchid , Dr. Mohammad Othman , Dr. Basem Othman , Dr. Attiya Al-zahrani
Corresponding Author Dr. Attiya Al-zahrani
Department of General Surgery, Al-Hada Armed Forces Hospital, Al-Hada Armed Forces Hospital, Taif 21947nSaudi Arabia - Saudi Arabia
Submitting Author Dr. Mohammad Othman
Other Authors Dr. Samah Khayat
Department of General Surgery, Al-Hada Armed Forces Hospital, Al-Hada Armed Forces Hospital, Taif 21947 nSaudi Arabia - Saudi Arabia

Dr. Alaa Al-Juaid
Department of General Surgery, Al-Hada Armed Forces Hospital, Al-Hada Armed Forces Hospital, Taif 21947 nSaudi Arabia - Saudi Arabia

Dr. Arif Khorchid
Department of General Surgery, Al-Hada Armed Forces Hospital, Al-Hada Armed Forces Hospital, Taif 21947nSaudi Arabia - Saudi Arabia

Dr. Mohammad Othman
King Abdullah Medical City, Maternity and Children Hospital, Madinah, Saudi Arabia, 84 Bradfield Road - United Kingdom M32 9LE

Dr. Basem Othman
General Surgery Department, Al-Hada Armed Forces Hospital, Al-Hada Armed Forces Hospital, Taif 21947 nSaudi Arabia - Saudi Arabia

SURGERY

Retrosternal Goiter, Substernal Goiter, Goiter, Intrathoracic Goiter, Thyroidectomy, Sternotomy, Cervicothoracotomy

Khayat S, Al-Juaid A, Khorchid A, Othman M, Othman B, Al-zahrani A. Retrosternal goiter with posterior mediastinal extension surgery in a patient with superior vena cava obstruction through a classic neck incision; Case report. WebmedCentral SURGERY 2015;6(5):WMC004890

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Submitted on: 08 May 2015 08:51:06 AM GMT
Published on: 08 May 2015 12:02:46 PM GMT

Abstract


Intrathoracic goiters are usually located anteriorly, in the superior or anterior mediastinum, and are termed substernal or retrosternal goiters. Posterior mediastinal goiters are rare, about 10% of all intrathoracic goiters. Patients with retrosternal goiter usually have a visible or palpable cervical mass. In addition, tracheal deviation may be present with compression symptoms.

Posterior mediastinal goiter with mediastinal compressive symptoms is an indication of surgery. Lateral thoracotomy is an alternative approach for intrathoracic goiter extending into the posterior mediastinum.

We report a case of 75 years old gentleman, referred with right neck swelling, difficulty in swallowing and breathing and changes of voice. Total thyroidectomy was performed. Histopathology report showed multi nodular goiter with no evidence of malignancy.

This patient had both types of extension. Both were delivered successfully through a classic neck incision without sternotomy or combined cervicothoracotomy. It would be reasonable to consider surgical management for such symptomatic goiters if there were no contraindications.

Introduction


Retrosternal goiter was first described by Haller in 1749 [1, 2]. From that time, there were controversies concerning its definition. The most common definition was proposed by deSouza and Smith, as that in which more than 50% of the total bulk of thyroid tissue resides below the thoracic inlet [1, 3, 4].

The intrathoracic thyroid adenoma or goiter is mostly located in the anterior mediastinum, about 8%-15% are in the posterior mediastinum [1, 3, 5, 6]. It is derived from embryonic thyroid tissue and developing into isolated thyroid tumor within the mediastinum or descending into the retrosternal loose tissue space from neck, which may cause various compressive symptoms when it reaches a certain size [1, 7, 8]. Most of the anterior mediastinal goiters can be removed by a transcerival approach, but posterior mediastinal goiters may require additional extracervical incisions [1, 4, 9].

Retrosternal goiter refers to the thyroid mass grows along dermal sternum from the neck to the substernal portion, descending below the thoracic inlet [4, 6]. It is characterized by slow progression and a longer course of illness [4, 5]. If the substernal goiter compresses the adjacent esophagus, trachea, nerves and blood vessels, then the corresponding symptoms would occur [4, 5, 8, 9]. These symptoms included anhelation and wheezing secondary to tracheal compression, superior vena cava syndrome caused by supe­rior vena cava compression, hoarseness caused by recurrent laryngeal nerve compres­sion, and Horner syndrome caused by periph­eral adrenergic nerve compression [2, 10, 11]. Some patients may be asymptomatic, and the abnor­malities were detected by physical examination [3, 6, 12].

Retrosternal nodular goiter usually results from simple goiter [5, 6, 13]. Although bilateral glands are often involved, the large lesions are usually located in unilateral gland [3, 12, 14]. Large substernal nodular goiter often causes compression of surrounding structures, secondary hyperthy­roidism and malignant changes [3, 4, 12, 14]. Therefore, sur­gery will be indicated when the diagnosis is confirmed. However, if it is treated with surgery, the operative bleeding risk was high [4, 6]. Most of the cases are operated upon via a cer­vical or combined cervical-thoracic approach. Substernal goiter resection performed through cervical approach is minimally invasive with less potential complications [1, 4, 6]. The patients don’t require thoracotomy and rehabilitate fast post­operatively. In contrast, combined cervi­cal-thoracic approach pose more risk of intra­operative damages and complications, as well as slower postoperative rehabilitation [1, 4, 6, 8].

The mediastinum constitutes a compartmentalized septum or partition that vertically divides the thorax [9, 15]. It is anatomically bound on the lateral side by the parietal pleural reflections along the medial aspects of both lungs, superiorly by the thoracic inlet, inferiorly by the diaphragm, anteriorly by the sternum, and posteriorly by the anterior surfaces of the thoracic vertebral bodies [9, 11, 13, 16].

Swallowing, gravity and thoracic negative pressure help the growing goiter direct into the chest cavity [4, 9]. Anatomically speaking, goiter in the chest cavity generally grows to the position of relatively low resistance. At first, the tumor will grow into the anterior superior mediastinum between trachea and sternum, forming the common retrosternal thyroid goiter [1, 4, 6]. Because there are thymus (which may atrophy), left and right brachiocephalic veins and superior vena cava in the front, aortic arch and its three branches (phrenic nerve and vagus nerve have smaller resistance) in the middle left of retrosternal space, tumor growth will be resisted there [1, 4]. Right posterior mediastinum has relatively low resistance than left posterior mediastinum, and it helps form right posterior mediastinal goiter. The primary intrathoracic goiter only accounts for 0.2 ~ 1% of all the intrathoracic goiters, it affects females more often (male: female = 1 : 3 or 1 : 4). Its causes are totally different from the ones of secondary intrathoracic goiter [1, 4, 9, 12]. During the embryonic developmental period of thyroid gland, part or all of the thyroid blastoma leaves primordium and is pulled into the thoracic cavity by the descendent heart and great vessels, then continues to develop in the thoracic cavity, forming the final primary intrathoracic goiter [1, 2, 7, 12]. Because of different originations, secondary posterior mediastinal goiter is often continued with the cervical thyroid gland, with blood supply from inferior thyroid artery and its branches while primary posterior mediastinal goiter maintains little or no connection with the cervical thyroid gland, and has a blood supply derived from intrathoracic arteries [3, 7, 12].

Radiographic image is the most effective and necessary diagnostic method for intrathoracic goiter[1, 13]. CT scan is the most common one for preoperative evaluation. On CT films, intrathoracic goiter usually manifests as a clear boundary mass, its density varies due to the amount of iodine contained: when the amount of iodine in the mass is low, its density is close to the soft tissue of chest wall, and when the amount of iodine is high, its density could be greatly higher than soft tissue [1, 4, 9, 13]. In addition, its density can be uneven due to colloid cysts and calcified plaque. Radionuclide scan is also one of the common diagnostic methods, but it is not so effective when compared with its usage in thyroid goiter of other regions because the intrathoracic goiter does not always uptake iodine [1, 5, 7, 12].

Fine-needle aspiration cytology to exclude the presence of carcinoma is not recommended because intrathoracic goiters are not easily accessible and the procedure may lead to life threatening complications [1, 3, 7]. When mediastinal mass lesions are diagnosed using imaging techniques, image interpretation requires accurate assessment of the lesion origin, area of existence, extension and inner structures [3, 4, 6, 7].

The surgical approach used to gain access to RSG is commonly based on intraoperative findings [1, 7]. The use of CT scanning to aid in this decision has always been limited, but now, it is gaining popularity among many surgeons. Several have emphasized on the importance of CT in preoperative planning of surgery for RSG. Extension to the level of the aortic arch and beyond was found to greatly influence the need for a thoracic approach [1, 2, 7, 10].

The differential diagnosis of intrathoracic goiter are of great variety, it should be differentiated from lymphadenopathy, branchial cleft cyst, arterial aneurysm, neurogenic tumour, pheochromocytoma, spinal cord injury, hiatus hernia, etc [1, 7, 9].

Case Report


75 years old Saudi gentleman, presented to endocrine surgery clinic in Al-Hada Military Hospital, Taif, Saudi Arabia. Patient known to have bronchial asthma, he was referred to the with right neck swelling, difficulty in swallowing and breathing and changes of voice. On examination, the face was congested with dilated with congested neck and upper chest veins (Fig. 1). Air entry was decreased on the right side of the chest but there was no tracheal deviation. There was a 5x6 cm lump on the right side of the neck which was mobile with swallowing. Biochemically, he was euthyroid. Chest X-ray (Fig.2) showed a well-defined huge mediastinal soft tissue dens lesion with tracheal compression. CT with contrast showed heterogeneous bilateral neck masses. The right side mass was 7x5 cm pushing the pharynx to the left and the right carotid laterally (Fig. 3).  Added to that, the left side mass was 11X6 cm with intra-thoracic extension down to the carina  compressing and pushing the trachea to the right side (Fig.3). There was compression on the superior vena cava (Fig. 4) with multiple collaterals on the upper anterior chest wall. There was no cervical or mediastinal lymphadenopathy. Total thyroidectomy was performed through a classical transverse cervical "collar" incision with no complications (Fig. 5). Histopathology report showed multi nodular goiter with no evidence of malignancy. The right lobe weighed 203g and the left lobe weighed 218 g. The patient had a smooth post-operative recovery and was in a good condition when followed up in the clinic.      

Discussion


Intrathoracic goiters represent downward extension of cervical thyroid tissue into the thoracic cavity through the thoracic inlet. With progressive enlargement of the gland, the path of least resistance is inferiorly into the thorax [1, 5, 7, 9]. The weight of the goiter as well as normal swallowing and respiratory motion favors mediastinal displacement [1, 9]. They are usually located anteriorly, in the superior or anterior mediastinum, and are termed substernal or retrosternal goiters. Their incidence in the general population is about 1:5000.  Retrosternal goiters are seen in 5-16% of all thyroidectomies. Most of them are benign, although thyroid cancer is identified in a small, but definite number (2.5-15%) of cases. Posterior mediastinal goiters are rare, comprising only about 10% of all intrathoracic goiters [1, 4, 9].

Initially, many patients are asymptomatic, but later obstructive symptoms and signs may develop, due to compression and displacement of trachea, bronchi, esophagus or large veins [1, 7, 9, 13]. Patients with retrosternal goiter usually have a visible or palpable cervical mass on presentation. In addition, tracheal deviation may be present. Exertional, nocturnal or positional dyspnea is the most common complaint, seen in 30-60% of cases [2, 11, 16]. Stridor, wheezing, cough, dysphonia or hoarseness as a result of recurrent laryngeal nerve compression are other common symptoms. A positive Pemberton's sign, facial flushing and choking on lying down, occurs primarily due to maneuvers that force the thyroid into the thoracic inlet. A variety of other symptoms can be induced by obstructive goiter. Dysphagia results from esophageal compression [1, 2, 4, 9]. Features of phrenic nerve paralysis, Horner's syndrome due to compression of the cervical sympathetic chain may be present too, and may be indicative of a malignant process. Occasionally, patients suffer acute hemorrhage into the goiter which may cause sudden potentially fatal tracheal obstruction. Rarely, jugular vein thrombosis, cerebrovascular steal syndrome or even superior vena cava syndrome have also been reported. The duration of symptoms may range from months to decades. The onset of obstructive symptoms may be more acute, and the patient's dysphagia may result in recurrent aspiration pneumonia [4, 9, 12]. The prevalence of hyperthyroidism ranges from 0% to nearly 50%. Posterior mediastinal goiters should be differentiated from other mediastinal masses by appropriate work-up. Thyroid function tests must be measured in any patient with a goiter or mediastinal mass suspected to be enlarged thyroid. Substernal goiters can be seen on chest x-ray as a superior mediastinal widening, often unilateral, with or without tracheal deviation or narrowing. Cervical and thoracic computed tomography is the most valuable imaging technique for evaluating mediastinal and cervical masses and diagnosing enlarged thyroid as the cause of that mass [1, 2, 9, 12]. On CT, mediastinal goiter should show high attenuation values due to iodine content, similar to normal thyroid. Nodular elements may show combinations of hypodensity and calcification [3, 7]. The mediastinal goiter is usually continuous with the thyroid tissue seen in the neck. Iodinated contrast agents should not be given routinely due to probability of inducing or exacerbating hyperthyroidism in this category of patients [7]. If contrast agent administration is required, a patient with subclinical or overt hyperthyroidism should be prepared by antithyroid drugs to prevent thyroidal iodine organification. Thyroid ultrasound is not as accurate in the retrosternal region as in the anterior neck because of inaccessibility to the ultrasound transducer. Although thyroid radionuclide imaging with iodine-123 may define areas of autonomous function in large cervical goiters [2, 7]. It is not so useful or even misleading in patients with intrathoracic goiter, because some of them take up radioiodine poorly, and the radioactivity is attenuated by interference from the sternum, clavicles, mediastinum tissue and blood pool. Pulmonary function tests, spirometry with flow-volume loops, may be abnormal even when the patient is asymptomatic. A barium esophagogram may be helpful in confirming esophageal compression from a goiter as the cause of dysphagia [2, 7, 9].  Surgical selective approach for excision of posterior mediastinal goiters is now recommended by most surgeons for symptomatic obstructive goiters. Many patients require surgery for symptomatic relief and to reduce the risk of acute exacerbation of compressive symptoms from hemorrhage or inflammation of the intra-thoracic gland. Observation rather than surgery is recommended for elderly asymptomatic patients who are not a good candidates for surgery, with slow growth, especially if inferior edge of mass is above brachiocephalic vein [4, 6, 7, 9, 12].

The typical anterior substernal goiter can almost always be removed through a cervical incision, although a partial or complete sternotomy may facilitate removal of a large gland [1, 9]. Although many posterior mediastinal goiters can be removed through a cervical incision, most surgeons have adopted a selective approach. Thoracotomy or a combined cervicothoracic approach has been advocated for larger lesions, when the mass is mainly intrathoracic with little or no cervical component or when the mass is malignant [1, 2, 9].

Conclusion


Posterior mediastinal goiter with mediastinal compressive symptoms is an indication of surgery. Lateral thoracotomy is an alternative approach for intrathoracic goiter extending into the posterior mediastinum making presentation atypical. Posterior mediastinal goiter can be differentiated from other posterior mediastinal masses by appropriate investigation, while computed tomography is the most valuable technique that may facilitate earlier diagnosis. In our case, the patient had both types of extension; retrosternal on the right side and to the posterior mediastinum on the left side, both were delivered successfully through a classic neck incision without sternotomy or combined cervicothoracotomy. It would be reasonable to consider surgical management for such symptomatic goiters if there were no contraindications.    

References


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