Introduction

In mediastinal masses, video-assisted thoracoscopic surgery (VATS) is used for diagnosis, staging, and treatment [1, 2]. VATS was initially used in the removal of tumors of limited size (< 5 cm), especially neurogenic tumors, bronchogenic cysts, and some pleura-based masses [3]. More recently, VATS in mediastinal masses and cysts has been widely used for diagnostic or therapeutic purposes in selected cases [4]. This practice is increasingly being used in the diagnosis and treatment of benign mediastinal masses, because of the advantages of VATS tools and techniques and as it is less invasive and has fewer side effects compared to open surgery, and provides a shorter healing period, earlier return to work, and lower costs [5].

In our study, 44 benign mediastinal mass cases, treated by VATS in the single thoracic surgery center, were retrospectively evaluated. The cases were evaluated in terms of age, sex, complaints, clinical findings, localization, size, diagnostic evaluations, pathologies, hospital stay, and complications, and were compared to the information in the literature.

Material and Method

Forty-six of the 178 cases of benign mediastinal masses were treated using the VATS method in our clinic, between January 2009 and January 2015. The researchers were able to obtain information regarding 44 of 46 patients with VATS, who were reported to have pathologically benign mediastinal masses, and these cases were evaluated retrospectively. The cases were evaluated in terms of age, gender, complaints, clinical findings, lesion localization, preoperative radiological evaluation, computed tomography (CT) and pathologic dimension, histopathological diagnosis, hospital stay and early postoperative period (first seven days) complications; and were compared with the literature.

The study includes the cases that underwent total excision by VATS due to mediastinal mass, and with a benign histopathology. The average follow-up period of the cases was 7.2 months (2-26 months). Patients who were started with VATS approach and converted to open surgery (because of intraoperative complications or surrounding tissue invasion) were not included in the study. Pathologies regarding heart, large vessel, lung, diaphragm, skeletal structures, and metastatic tumors were excluded from the study.

Results

Forty-four benign mediastinal masses treated by VATS in our clinic were included in the study. Twenty-eight of our cases were female, 16 were male, and the mean age was 49 (19-75). Left-sided VATS was applied to 9 (20.5%) cases, whereas right-sided VATS was applied to 35 (79.5%). Thirty-four (77.3%) of the benign mediastinal masses treated with VATS were cystic and 10 (22.7%) were massive. The rate of asymptomatic cases was 27.3%, 22.7% of the cases had shortness of breath, 20.5% had chest pain, 11.4% had coughing, 4.5% had hemoptysis, 4.5% had myasthenia gravis , 4.5% of patients had indole weakness, 2.3% had back pain, and 2.3% had dysphagia (Table 1).

There were two patients who presented with hemoptysis complaint: a 69-year-old female patient with a 5 cm bronchogenic cyst located in the visceral mediastinum and a 75-year-old male with a 6 cm parathyroid cyst located in the visceral mediastinum. The hemoptysis was suspected to have hemorrhagic origin due to cystic degeneration.

Myasthenia gravis (MG) was determined to affect only two cases of all patients with thymic pathology. A 33-year-old male with a 5 cm mass lesion located at the anterior mediastinum and a 33-year-old woman with a 2.5 cm mass lesion located at the anterior mediastinum were histopathologically diagnosed with thymic hyperplasia. During the follow-up period, MG findings were observed to have decreased in both cases.

All of our cases were evaluated by PA chest x-ray and all cases were evaluated by thorax CT. The additionally requested diagnostic examinations were as follows: three mediastinal cysts and three thymic lesions, thorax magnetic resonance imaging (MRI); two mediastinal cysts, echocardiography; one mediastinal cyst, MRI angiography; one mediastinal cyst, CT angiography; two parathyroid cysts, thyroid USG and parathyroid scintigraphy; and 1 mediastinal cyst, PET- CT. Invasive procedures for diagnostic purposes were not performed except for the imaging methods. VATS was applied for the treatment of lesions with cystic maturity in the imaging examinations and for the diagnosis and treatment of the lesions with solid maturity.

Mediastinal cysts (38.6%) and thymic lesions (38.6%) were the most common pathological diagnoses. Bronchogenic cysts were the most common mediastinal cysts, and thymic hyperplasia was the most common among thymic lesions (Tables 3 and 4). In our study, lesions were most commonly detected on the anterior mediastinum (50.0%). In the anterior mediastinum, the majority (72.7%) were thymic lesions. Mediastinal cysts (73.3%) were seen frequently in the visceral compartment (Table 2).

Bronchogenic cysts (41.1%), which are foregut cysts, were the most common among the mediastinal cysts (Figure 1). Among seventeen cystic lesions, bronchogenic cysts are followed by pericardial cysts (35.2%), paraesophageal cysts (17.6%) and parathyroid cysts (5.8%). The distribution of mediastinal cysts by region is presented in Table 3.

Sixteen (94.1%) of 17 thymic lesions completely resected with VATS, had anterior mediastinal localization. Only one case of thymoma was localized in the visceral compartment. Ten patients had thymic hyperplasia (58.8%). They made up 22.7% of all mediastinal benign masses. Five of the thymic lesions were thymoma (29.4%) and they made up 11.3% of all benign mediastinal masses (Figure 2). There was thymolipoma in one case, and atrophic thyroid tissue was detected in another case (Table 4). The average size of the lesions was 3.56 cm (1.5-6.0 cm).

One of the two neurogenic tumors was detected in the posterior compartment and the other was detected in the anterior mediastinum. Both of our cases were diagnosed as schwannoma (Figure 3). The incidence among all benign mediastinal cysts was calculated as 4.5% (Table 2).

Mesenchymal tumors constituted 4.5% of the patients in our study group. In both cases, the diagnosis was reported as a solitary fibrous tumor. The lesions were located in the posterior compartment.

Among the other benign mediastinal pathologies included in our study, two cases of Castleman’s disease with visceral and anterior mediastinal localization, two cases of parathyroid adenomas localized to visceral mediastinum, and two mature cystic teratoma cases localized in the anterior mediastinum were also successfully excised by VATS.

The average hospital stay was 5.5 days (2-14 days). In our study, 40 patients (90.9%) had no complications, two patients (4.5%) had prolonged air leak, one case (2.3%) had hemorrhage and one case (2.3%) had atelectasis.

Aspiration was performed with posterior drainage and fiberoptic bronchoscopy due to the development of postoperative atelectasis in the 69-year-old male patient with Castleman’s disease. A 46-year-old woman with thymic hyperplasia developed hemorrhagic drainage on the first postoperative day, which could be controlled with one unit of fresh frozen plasma, and was controlled without the need for revision. A 57-year-old female patient with thymic hyperplasia and a 69-year-old female patient with mediastinal cyst developed postoperative prolonged air leak.

In the follow-up period, recurrence was seen in two cases. A 68-year-old woman was diagnosed postoperatively with pericardial cyst 2 years later and a 50-year-old male patient was diagnosed postoperatively with type B1 thymoma recurrence 1 year later.

Discussion

Primary tumors and cysts of the mediastinum are most commonly localized in the anterior mediastinum. This is followed by posterior mediastinal and visceral mediastinum [1, 2]. In our study, we found pathology in the anterior mediastinum to be the most common, with the rate of 50.0%; 34.1% of the cases were visceral, 15.9% were posterior mediastinal.

According to Donahue, thymomas are the most common mediastinal tumor in adults [6]. Mullen and Richardson have reported that in adults, 47% of anterior mediastinal tumors were composed of thymic lesions [7]. The most common mediastinal lesions according to localizations are thymomas in the anterior, enteric cysts in the visceral, and schwannomas in the posterior [6]. In our study, thymic hyperplasia (22.7%) was the most common among all benign mediastinal pathologies. In compliance with the literature, thymic lesions (72.7%) were the most common in the anterior mediastinum. The mediastinal cysts (73.3%) were found to be more common in the visceral compartment.

Signs and symptoms in mediastinal masses depend on the localization, the size, whether the lesion is benign/malignant, whether it is infected, and whether specific endocrine or biochemical products are released. Symptoms that can be seen due to the compression, invasion, and infection in mediastinal masses are as follows: coughing, stridor, dyspnea, dysphagia, voice anomaly, chest pain, vena cava superior syndrome, pleural effusion, pericardial effusion, Horner’s syndrome, upper extremity pain, paraplegia, diaphragmatic palsy [1-6]. In our study, 27.3% of the cases were asymptomatic, 22.7% had dyspnea, 21.7% had chest pain, 11.4% had coughing, 4.5% had weakness, 4.5% had hemoptysis Myasthenia gravis in 4.5%, weakness in 2.3%, dysphagia in 2.3% and back pain in 2.3%.

Chest X-ray, thorax computerized tomography, magnetic resonance imaging, positron emission tomography, and thyroid scintigraphy can be used for non-invasive diagnosis of mediastinal lesions [8]. We also used a PA chest X-ray for the initial evaluation of all our cases, and all cases were evaluated with thorax CT. Six patients were preoperatively diagnosed additionally using thoracic MRI, 2 patients were diagnosed by echocardiography, 1 patient by MRI-angiography, 1 patient by CT-angiography, and 1 patient by PET-CT.

Mediastinoscopy, anterior mediastinotomy, mediansternotomy, VATS, thoracotomy, thoracotomy combined with sternotomy are the surgical methods for the diagnosis and treatment of mediastinal masses [9,10].

VATS is an important surgical method of the diagnosis and surgical treatment of mediastinal masses. The size, histologic features and residential area of the mass are very important in the planning of surgery. Even very large masses (> 10 cm) can be resected by VATS procedure [8]. The patient’s operating position, and the use of 30-degree lens and ultrasonic or bipolar cutters makes these operations possible. VATS technique is primarily recommended in the treatment of mediastinal cysts. In addition, the vast majority of neurogenic tumors, thymic lesions, and benign germ cell tumors can also be resected by VATS [3, 4].

The VATS method has started to be more preferred than the open surgical approaches for mediastinal masses because of the significantly better postoperative comforts of the patients, shorter hospitalization times, shorter time to return to normal life, less postoperative pain, and fewer postoperative complications [3, 5].

Tumors originating from anterior mediastinal thymus are the main group in the VATS approach. It has been suggested in particular that stage 1 and 2 thymomas can be resected by VATS in thymomas [11]. During VATS thymectomy, the thymoma, thymus and all mediastinal fatty tissue should be removed. Complete dissection of the innominate vein and exploration of the bilateral phrenic nerves should be achieved [11-12].

In addition to being an effective and safe method of transsternal thymectomy, the use of video-assisted thoracoscopy allows to have less surgical trauma, less postoperative pain, preservation of pulmonary functional capacity in the postoperative period, shortened hospital stay and cosmetic advantages. Thus, VATS is currently increasingly preferred. As a result of the studies, it has been suggested that VATS should be applied in thymomas smaller than 3 cm and after at least 60 thymectomies [11, 13]. In our study, the average pathological dimension of the lesions treated with VATS thymectomy was 4.3 cm.

It is reported that 95% of thymomas are located in the anterior mediastinum [14, 15]. In our series, four of five cases (80%) of the thymoma were anterior mediastinal. It has been reported to be seen mostly in the 5th and 6th decades [14]. In our study, the mean age was 52.8, in compliance with the literature. As an exception, one case was detected at 39 years of age and the diagnosis was mixed type thymoma. Myasthenia gravis (MG) association can be seen in 30-73% of thymoma cases [12-15]. In our study, MG was not observed in patients with thymoma, but MG was present in two thymic hyperplasia cases.

Rare case reports include thymolipomas that are resected by VATS. In our study, one case of thymolipoma, that was 4 cm in size, was successfully excised by VATS.

In our study, mediastinal cysts (38.6%) were the most common along with thymic lesions (38.6%). VATS should be preferred against thoracotomy in cases with mediastinal cystic lesions, because of its current advantages, as long as the cyst can be completely excised by VATS [16]. In our study, bronchial cysts (41.1%) were the most common mediastinal cysts that could be excised by VATS, and pericardial cysts (35.2%) were the second most common. Even if asymptomatic bronchogenic cysts are present, surgical excision is recommended because of the precise tissue diagnosis, prevention of perforation and risk of malignant transformation [17, 18]. However, in symptomatic cases, surgery is the only option and total excision of the cystic lesion is necessary. If total excision cannot be performed, recurrence may develop [18]. In our study, one case of pericardial cyst recurred 2 years after surgery.

Neurogenic tumors are tumors which mostly consist of schwannomas or ganglioma, which are rarely malignant, with posterior mediastinal paravertebral sulcus placement [19, 20]. Treatment consists of surgical resection. Surgery removes symptoms associated with local growth, confirms the diagnosis, and excludes malignancy. In addition, long-term malignant degeneration is also prevented [4, 19]. Hazelrigg et al. found that among 23 patients that underwent VATS due to neurogenic tumors had a mean hospitalization time of 2 days (1-9) [21]. Transcervical, thoracotomy, and VATS approaches were compared in another series of twenty-three cases, and the duration of hospital stay and blood loss were significantly lower in the VATS-treated patients compared to the other groups [22]. In our study, two neurogenic tumors were successfully excised by VATS. Postoperative hospitalization time was 5 and 7 days, and no complications occurred in the two patients.

Germ cell tumors constitute 10-20% of mediastinal masses. Although they are frequently anterior mediastinal, 3-8% of them can be placed in the posterior mediastinum. Patients who cannot be diagnosed by non-surgical methods require excision for definitive diagnosis and treatment purposes [23]. In our study, both germ cell tumor cases we excised with VATS were located in the anterior mediastinum.

Mesenchymal tumors constitute less than 6% of mediastinal lesions [24]. In our study, benign mesenchymal tumors located in the posterior compartment constituted 4.5% of all benign mediastinal lesions.

In our study, we found two rare cases of Castleman’s Disease that we excised by VATS. Castleman’s disease, a benign lymph node hyperplasia, is usually asymptomatic and most patients are diagnosed under the age of 30 [25]. The average age of the cases in our study was 65 years.

VATS can also be used in the surgery of endocrine system-derived tumors. Twenty percent (20%) of the parathyroid glands with primary or secondary hyperparathyroidism are ectopic and 1-2% are localized in the mediastinum. Adenomas localized in the anterior mediastinum, or in the paratracheal area, especially those that are localized ectopically in the mediastinum, can be resected by VATS [25]. In our study, two parathyroid adenomas were successfully excised with VATS, and patients were discharged on the 3rd and 7th day without postoperative complications.

In the invasive diagnosis and treatment of mediastinal masses, localization and pathological diagnosis of the lesion are determining factors. Surgical approach with VATS is important in the diagnosis and treatment of mediastinal lesions except for limited cases.

In cases that are appropriate for VATS in the surgical treatment of mediastinal masses and cysts, VATS should be preferred to open surgical methods due to reduced hospitalization time, return to normal life or work, shorter postoperative pain, fewer postoperative complications.

VATS should be considered primarily in the treatment of mediastinal cysts. In addition, VATS should be the first choice for the treatment of neurogenic tumors, thymic lesions, benign germ cell tumors, and parathyroid adenomas.

Scientific Responsibility Statement

The authors declare that they are responsible for the article’s scientific content including study design, data collection, analysis and interpretation, writing, some of the main line, or all of the preparation and scientific review of the contents and approval of the final version of the article.

Animal and human rights statement

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. No animal or human studies were carried out by the authors for this article.

Funding: None

Conflict of interest

None of the authors received any type of financial support that could be considered potential conflict of interest regarding the manuscript or its submission.

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