Giant middle mediastinal lesions: when tumor size correlates with mesenchymal origin-a retrospective single-center analysis

Background

The International Thymic Malignancy Interest Group (ITMIG) proposed an internationally accepted division of the mediastinum into three compartments based on computed tomography (CT): anterior (prevascular), middle (visceral) and posterior (paravertebral) compartment. There is no generally accepted definition for the term "giant" when applied to middle mediastinal lesions. We defined the term "giant" and described our surgical experience in treating patients with giant lesions of the middle mediastinum.

Methods

CT imaging of patients operated in our center from January 2016 to August 2021 for mediastinal lesions was reviewed. Lesions were categorized to one of the ITMIG-defined compartments. Lesion size at diagnosis was measured at its largest diameter on axial CT imaging. Giant middle mediastinal lesions were defined as lesions having a size ≥90th percentile of our middle mediastinal lesion cohort. Patients with giant middle mediastinal lesions were further analyzed.

Results

Thirty-six patients (23%) had lesions located in the middle mediastinal compartment. Most common diagnoses were mediastinal cysts (n=10, 28%), metastatic lesions (n=6, 17%), lymphomas (n=5, 14%), and sarcomas (n=3, 8%). Ninetieth percentile lesion size was 73 mm. As per definition, four patients had giant middle mediastinal lesions. All these four lesions were of mesenchymal origin including oesophageal leiomyoma, synovial sarcoma, leiomyosarcoma and undifferentiated round cell sarcoma. Resection was performed through posterolateral thoracotomy or sternotomy, with or without cardiopulmonary bypass.

Conclusions

The term "giant" could be defined as a mass larger or equal to 73 mm. This definition selected specifically lesions with mesenchymal origin and may therefore guide diagnostic algorithm and patient management.

A case report of a giant middle mediastinal leiomyosarcoma

Primary mediastinal leiomyosarcomas are extremely rare soft tissue tumors, accounting for less than 15% of all primary mediastinal sarcomas. Middle mediastinal tumors are very rare, with a prevalence of 0.1% in healthy individuals. Usually, mediastinal leiomyosarcoma originates and involves mediastinal structures such as oesophagus, heart or great vessels. Here we report the rare case of a giant middle mediastinal leiomyosarcoma without involvement of any surrounding structures in a 70 years old female. Main related symptoms were cough and increasing dyspnea. Imaging work-up showed an 11-cm giant middle mediastinal tumor located in the subcarinal space and compressing the oesophagus. Cytopathologic examination of endobronchial ultrasound-guided transbronchial needle aspiration diagnosed leiomyosarcoma. The tumor was completely removed through a right posterolateral thoracotomy in the fifth intercostal space. None of the surrounding structures were involved by the tumor intraoperatively. The patient underwent adjuvant chemoradiation as advised by the sarcoma tumor board (5 cycles of dacarbazine and doxorubicin followed by 60 Gy). At last follow-up, no evidence of recurrence was seen on imaging ten months after surgery. This rare case confirms that giant middle mediastinal leiomyosarcoma may not involve surrounding mediastinal structure and that resection can be completely and safely done without the need for resection of neighboring structures. The relevant literature on the subject is reviewed here.

Epicardial carvernous hemangioma: The diagnostic challenge of a middle mediastinal mass

Primary tumors in the middle mediastinum are rare and pose diagnostic challenges. Lymphomas, mediastinal cysts and thymomas most frequently affect this anatomic area. Primary cardiac tumors are rare and constitute a differential diagnosis for the inferior middle mediastinum. Surgical exploration and resection is often mandatory in order to make a definitive diagnosis. Here, we report the case of a 69 year-old women who presented with persistent dyspnea. A complete preoperative workup revealed a large tissular mass adjacent to the right atrium. A diagnosis of a typical epicardial cavernous hemangioma was made following surgical resection.

Ectopic thymoma in the middle mediastinum: A case report and literature review

ABSTRACT

Thymomas are typically located in the anterior mediastinum and are rarely identified in other locations. A 48-year-old male patient was admitted to the hospital due to myasthenia gravis (MG). A mass in the middle mediastinum, obstructing the superior vena cava, was revealed by computed tomography and magnetic resonance imaging examination. The postoperative diagnosis was thymoma type AB, stage III. After surgery, he was treated with radiation therapy neoadjuvant. At the 5-year follow-up, recurrence was not observed. Ectopic thymoma in the middle mediastinum has been reported in 26 other cases in the literature. Most were classified as thymoma type A or AB, and all were stage I or II. Most of them were located in the upper right mediastinum, adjacent to the right trachea, and in the retro innominate vein area. Thymoma should be considered a differential diagnosis when a mass is observed in the middle mediastinum.

Sarcoidosis Presenting as a Right Paraesophageal Mass Abutting the Left Atrium

We herein report a unique case of sarcoidosis in a 44-year-old Caucasian female. The patient was initially evaluated for hematochezia and diagnosed with diverticulitis after computed tomography (CT) scan of the abdomen and pelvis. This imaging also incidentally showed a large mass abutting the esophagus. Further imaging of the mass revealed widespread lymphadenopathy in the thorax without any respiratory or classic B symptoms present. The remaining workup caused concern for possible lung or hematologic malignancy. Following biopsy of a thoracic lymph node, the patient was diagnosed with sarcoidosis. This patient met only one of the usual demographic criteria associated with sarcoidosis and none of the lab criteria. While sarcoidosis is typically a benign disease, this case exemplifies how it may appear as a more sinister entity and warrants extensive workup to rule out malignancy.

A large schwannoma of the middle mediastinum: A case report and review of the literature

Schwannoma of the mediastinum is a rare and typically benign type of tumor. The present study describes the case of a 61-year-old woman who presented with a continuous cough and facial edema. Pre-operative chest radiography, enhanced computed tomography (CT) and three-dimensional CT scans identified a well-circumscribed mass. The large cyst, measuring 6.5×6.1×5.0 cm, was located anterior to the trachea and posterior to the superior vena cava. The mass was observed to be in close proximity to the right pulmonary hilum and the superior vena cava was flattened due to the pressure on the right vagus nerve. Therefore, the encapsulated tumor was completely resected under thoracoscopy and was subsequently diagnosed as a benign schwannoma upon pathological examination. The respiratory tract symptoms and facial edema resolved immediately after the surgery, and no recurrence was observed during the 6-month follow-up period. At the time of writing, the patient remained alive. The present study records the rarely successful resection of a middle mediastinal tumor by video-assisted thoracoscopy.