Complete surgical resection of a thymic cyst located in the middle mediastinum with extension into the carina through a neck incision: A case report study

Abstract

Introduction and significance

Thymic cysts are rare, located in the middle mediastinum, and are often asymptomatic and discovered incidentally. When they are symptomatic, the symptoms are often due to the effect of the mass, and complete surgical excision is preferred to avoid the risk of complications following their persistence.

Case presentation

We present a case of a patient who had recurrent dyspnea and was later diagnosed with a cystic formation in the middle mediastinum by radiological investigations and successfully treated through a neck incision and completely resected.

Clinical discussion

Many physicians fail to include these cysts in the differential diagnosis of cystic lesions in the middle mediastinum, thus missing the opportunity to successfully manage these benign formations.

Conclusion

The neck incision is considered suitable and has less surgical trauma and less injury than the previously used transthoracic surgical approaches and therefore may be used in the future for the resection of middle mediastinum lesions in general.

Highlights

• •Thymic cysts in the middle mediastinum are rare.
• •Most cases are discovered incidentally and are difficult to diagnose accurately before surgery.
• •Complete surgical excision is considered the gold standard treatment for these cysts.
• •In our case, a complete thymic cyst in the middle mediastinum was successfully removed using a neck surgical approach.

1. Introduction

Mediastinal cysts are generally considered rare, with the majority located in the middle mediastinum, accounting for approximately 12–20 % of mediastinal masses [1]. Thymic cysts are extremely rare, with some studies reporting them as constituting 1–3 % of all mediastinal masses. They are most often found in the anterior mediastinum [2]. Thymic cysts extending into the neck are very rare, located in the posterior mediastinum, and may be mistaken for another neck disease. Most thymic cysts occurring in the neck are found in children and are very rare in adults [3,4]. Thymic cysts can be congenital or acquired, with symptoms varying depending on their location in the mediastinum. They are sometimes discovered incidentally during radiological investigations for other conditions and are primarily treated surgically to prevent complications [5].

This case is described in accordance with the criteria of SCARE [6].

2. Presentation of case

2.1. Patient information

We present a case of a 27-year-old female who had been suffering for about 5 years from recurrent dyspnea that worsened during recumbency. She had previously been treated with medication without response. About a week ago, her dyspnea gradually worsened and she was referred to us for management. The patient did not mention any history of allergies or medications. There is no history of allergies or tumors in the patient's relatives.

3. Clinical findings

On arrival to our emergency department, the patient was in good general condition with no central or peripheral cyanosis and no signs of respiratory distress. No signs of apparent jugular vein distention, no signs of facial congestion. Chest examination showed no wheezing or rales and no heart murmurs.

On examination of the neck, the edges of a mass were palpated, located above the sternum and extending towards the chest, without being able to precisely define its edges.

4. Diagnostic assessment

Laboratory examinations revealed a hemoglobin of 14.8 g/dL, total white blood cell count of 13000/mm3, platelet count of 453,000/mm.

Tumor markers, including carcinoembryonic antigen (CEA), CA 125, CA 19–9, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin (β-HCG), were within normal limits.

Chest X-ray showing enlargement of the upper mediastinum with right tracheal deviation and a normal heart shadow (Fig. 1.A).

Fig. 1.

A: Chest X-ray before surgery showing.

Increased volume of the superior mediastinum (blue arrow) with tracheal deviation to the right side of the chest (green arrow) is seen.

B: Axial CT scan demonstrating The beginning of the cyst formation appears at the top of the neck (blue arrow) behind the trachea and pushes the trachea to the right and forward (green arrow).

C: Axial CT scan demonstrating The cyst is mainly located in the middle mediastinum (blue arrow).

D: Axial CT scan demonstrating The cyst is shown to reach the level of the carina (yellow arrow) and is adjacent to the pulmonary artery (blue arrow) and the pulmonary trunk. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

A computed tomography (CT) scan showed a cystic formation located behind the left thyroid lobe, pushing the trachea to the right and forward, and extending mainly with the majority of its volume towards the middle mediastinum reaching the carina, where it compresses the large blood vessels from behind(Fig. 1.B-D).

Regarding the biopsy using FNA, it was not performed due to the fluid content of the cyst and the fear of spreading the cyst contents.

5. Therapeutic intervention

Based on the above findings, it was decided to perform surgery. Under general anesthesia, a transverse incision was made in the neck, approximately 2 cm above the manubrium. The anatomical structures were exposed until the cystic formation was reached, where a thin-walled, soft cyst was found, directed towards the mediastinum. The cyst was dissected from the neck towards the middle mediastinum, taking care not to damage the pleura on both sides and ensuring its complete release until reaching the carina, where the cyst was completely removed through the neck incision.

During the surgery, care was taken to avoid damage to the blood vessels in the mediastinum, in addition to the presence of the esophagus behind the cystic formation and the importance of maintaining the nerve and blood support of the esophagus.

Histological examination showed multilocular thymic cyst (Fig. 2.B-C).

Fig. 2.

A: Histopathological examination demonstrated.

Pseudoepitheliomatous hyperplasia, commonly lymphocyts, hemorrhage, no atypia, no malignancy.

B: Histopathological examination demonstrated.

Multilocular cysts have more layers of cuboidal, columnar, micropapillary or mixed glandular epithelium.

The patient was monitored 48 h after surgery and discharged in good general condition, a wound with a cosmetic appearance (Fig. 3.A) and normal chest X-ray (Fig. 4.A).

Fig. 3.

A: Clinical image after surgery showing the surgical incision used to remove the cyst.

Fig. 4.

A: Chest X-ray Postoperative showing return to normal mediastinum size with normal tracheal position.

6. Discussion

When discussing diseases, it is essential to comprehend the underlying anatomical structures. One such crucial organ is the thymus gland. Originating embryonically from the third and fourth pharyngeal sinuses, the thymus gland migrates downward during fetal development, from the neck to its final position in the mediastinum. Consequently, any abnormalities in the thymus gland can manifest along its migratory pathway, from the neck to the mediastinum [[3], [4], [5], [6], [7]].

Situated in the anterior mediastinum, the thymus gland plays a pivotal role in the development of the human immune system. This gland is highly active during the neonatal period and prior to adolescence, gradually undergoing atrophy and eventual replacement by fat following puberty [7].

Several pathological conditions may arise from the thymus gland, such as cancers, lipomas, cysts, or thymic hyperplasia. Thymic cysts are considered a benign disease. Many attempts have been made to explain the development of these cysts, including that the cause of these cysts is congenital due to the continuation of the thymic ducts. Some have said that the cause of these cysts is an acquired cause due to the degeneration of some corpuscles with the continued presence of abnormal thymic remnants [[4], [5], [6], [7], [8]]Thymic cysts may form due to an acquired cause such as tumors such as Hodgkin's lymphoma or its treatment, and perhaps from infections such as tuberculosis, or perhaps after chest surgery [9]. The majority of thymic cysts are asymptomatic, and when they manifest with symptoms, they are due to their location, as they may manifest with dysphagia, shortness of breath, or hoarseness due to their mass effect [10].

Thymic cysts share similarities with other conditions such as thyroglossal duct cysts, cystic hygromas, skin and epidermal cysts, and bronchial cysts. Accurate diagnosis before surgery is challenging, and no radiological investigation can definitively confirm the diagnosis without histological examination.

A simple chest X-ray is the initial investigation for patients with chest symptoms or suspected chest lesions. A CT scan can then be performed to assess the lesion's relationship to adjacent structures and its extent, as it can visualize the shape and contents of the cyst, which may be single-chambered or multi-chambered. The sensitivity of CT scans in diagnosing thymic cysts is approximately 55 % [11].

In most cases of mediastinal lesions, surgeons attempt to obtain targeted biopsies via fine needle aspiration. However, for thymic cysts, pre-operative samples should not be obtained for histological examination, as they are often inconclusive and may lead to complications such as infection or death [12].

The gold standard treatment for mediastinal thymic cysts remains surgical excision, which offers excellent outcomes with a low complication rate of 1–6 % [13], While some authors have discussed surveillance as an option for these cysts, the risk of complications associated with thymic cysts, including bleeding, compressive effects, or the presence of occult cancer, makes surgery the preferred approach [5].

Surgical techniques and approaches vary depending on the location of the thymic cyst, but all aim for complete excision.

7. Conclusion

It is not common for thymic cysts to be located in the middle mediastinum and extend into the neck, which makes their management unclear and confusing for surgeons and confuses the appropriate surgical approach. Therefore, our case presented a new and different surgical technique for the successful removal of mediastinal cysts and great cosmetic results.

Abbreviations

CEA

carcinoembryonic antigen

AFP

alpha-fetoprotein

β-HCG

beta-human chorionic gonadotropin

Provenance and peer review

Not commissioned, externally peer-reviewed.

Ethical approval

Ethical approval for this study (Ethical Committee N° NAC 207) was provided by the Ethical Committee NAC of Damascus hospital, Damascus, SYRIA on 6 July 2024.

Guarantor

Ali Alrahil

Sources of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Consent of patient

Written informed consent was obtained from the patient's parents/legal guardian for publication and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Author contribution

Ali Alrahil: Conceptualization, resources, who wrote, original drafted, edited, visualized, validated, literature reviewed the manuscript, and the corresponding author who submitted the paper for publication.

Khaled Alomar: Supervision, visualization, validation, resources, and review of the manuscript.

Walat Omar: Visualization, validation, and review of the manuscript.

Alhasan Rastanawi: Visualization, validation, and review of the manuscript.

Naser Alshaikh M.D. PHD.: Supervision and scientific review, writing and proofreading the manuscript.

All authors read and approved the final manuscript.

Declaration of competing interest

The authors declare that they have no competing interests.

Availability of data and materials

The datasets generated during and/or analyzed during the current study are not publicly available because the Data were obtained from the hospital computer-based in-house system. Data are available from the corresponding author upon reasonable request.