Germ cell tumors, frequently observed in the gonads, can also be found in the (anterior) mediastinum, which is the most predominant extragonadal site, and manifests as a mature teratoma accounting for the majority of primary germ cell tumors in the mediastinum. Most mediastinal mature teratomas are insidious and therefore are generally discovered during abnormal medical examinations. Teratomas usually compress adjacent structures, predominantly altering the respiratory and circulatory systems. Another typical feature of mediastinal mature teratoma is tumor bleeding or rupture into the bronchus, pleura, vessel, or pericardium. Mediastinal mature teratoma can be definitively diagnosed by histopathological examination as the tumors are generally composed of ectodermal, mesodermal, and endodermal derivatives. Video-assisted thoracoscopic surgery (VATS) technology has evolved from its multiport origins to even less invasive approaches due to its identified advantages compared with open surgery for a series of thoracic cavity tumors. During the course of its evolution, Uniportal VATS (UniVATS) has emerged, which has proved to be superior to multiport VATS and has extended the surgical boundaries. In the present case, we describe a giant mature teratoma in the anterior mediastinum of a 31-year-old male with complex rupture into the right lung and compression of the right atrium, as well as the superior vena cava and ascending aorta, which was completely resected using UniVATS.
A 31-year-old male patient was admitted to our hospital complaining of progressive chest pain, exertional dyspnea and cough, accompanied by recurrent hemoptysis, and a low-grade fever. The patient had been treated with antibiotics for 5 d, but this was unsuccessful in relieving his symptoms.
History of present illness
Chest pain and exertional dyspnea in this patient started 6 wk ago, and recurrent hemoptysis developed 10 d previously.
History of past illness
The patient had no previous medical history.
Personal and family history
The patient had no disease-related personal or family history.
Physical examination on admission showed that the patient was normothermic and normotensive, without tachypnea, cyanosis or tachycardia. In addition, no abnormalities of features, thyroid, lung fields, abdomen, skin, arms and legs, lymph nodes, or testicles were observed during the examination. Neurological examination and routine stool as well as urine analysis were generally within normal limits. A 12-lead resting electrocardiogram demonstrated sinus rhythm.
Routine blood test showed a slightly higher C-reactive protein level of 12.98 mg/L, suggesting a mild inflammatory response. Tumor markers, such as CEA, AFP, CA-125, NSE, β-HCG, and CA 19-9, were within normal ranges, except for TK1 (5.60 pmol/L). In addition, no abnormalities were found following respiratory function tests. Transthoracic echocardiography in the parasternal view revealed a normal-sized heart with normal function and blood flow velocities.
An earlier computed tomography (CT) report from a local hospital showed a large oval mass measuring approximately 9.0 cm × 6.0 cm × 5.0 cm in the anterior mediastinum. To further define the location, nature, composition, characteristics, and operability of the tumor, contrast-enhanced CT of the chest and soft tissue three-dimensional reconstruction were performed, which confirmed the presence of a right anterior mediastinal mass with extrinsic compression of the right atrium and right lung (Figure 1).
Figure 1 Enhanced chest computed tomography scan before surgery.
A: In the coronal mediastinal window, the presence of a right hilar enlargement.an emerging cavity with high-density consolidation, high-density opacities occupying the right upper and middle lobe, diffuse high-density opacities with shadows and stripes, irregular soft tissue of mixed density in the anterior right upper mediastinum, and consolidation with cavitation and calcification adjacent to the mediastinum are shown; B: In the mediastinal window; C: In the lung window.
Further diagnostic work-up
Moreover, contrast-enhanced CT further revealed an oval, polycystic, heterogeneous mass with fatty, liquid and calcified components in the right anterior mediastinum, measuring 8.3 cm × 4.4 cm × 4.8 cm in size. The mass was closely related to the surrounding tissues and organs, presenting as infiltration of the right upper and middle lobes with pneumonitis, and encased the origin or terminal of the superior vena cava as well as the ascending aorta. Heterogeneous enhancement of the mass was confirmed following administration of Ultravist 300.
The patient underwent VATS via a uniportal right-sided anterior approach with surgical resection via the 5th intercostal space on day 7 after admission. The extracorporeal circulation system was prepared in advance for possible intraoperative haemorrhage. Intraoperative thoracoscopic exploration revealed extensive adhesions around the thorax, including a large mass measuring approximately 9 cm × 6 cm × 5 cm, located in the right anterior mediastinum. The tumor was located above the superior border of the left brachiocephalic vein and was partially solid and cystic in nature. Moreover, the tumor was adjacent to the pericardium, the terminal superior vena cava and the left brachiocephalic vein, and infiltrated the right upper and middle lung lobes and the right phrenic nerve, and it was extremely difficult to separate the mass. We therefore performed en bloc resection of the giant teratoma, a wedge resection of the upper and middle lobes of the right lung, and partial pericardial resection in this patient. The tumor was resected with utmost care to preserve vital structures, such as the phrenic nerve, recurrent laryngeal nerve, aorta, superior vena cava, left brachiocephalic vein, pulmonary vessels, and subclavian vessels. In addition, the enlarged mediastinal lymph nodes and the right portion of the thymus were also resected to ensure that no tumor tissue remained. Basal thoracostomy tubes were placed.
The gross pathological diagnosis revealed a predominantly mature cystic teratoma with a foreign-body reaction that measured 10 cm × 6 cm × 4.5 cm (Figure 2). The tumor infiltrated the lung, and the tissue was filled with sebaceous materials. An immunohistochemical diagnosis was conducted and showed positive markers of epithelial as well as T cells. However, neither mesenchymal nor neural elements were observed (data not shown). Moreover, there was no histological or morphological evidence of malignancy in the tumor (Figure 3). In addition, atrophic thymus and inflammatory lymph nodes were observed in the tissue surrounding the tumor.
Figure 2 The images of surgical specimen histopathology.
Surgical specimen’ largest diameter was 10 cm. A: The macroscopical image of the mass; B: Cut of the mass shows sebaceous material; C: Image of the cartilage tissue of the mass.
Figure 3 Hematoxylin and eosin staining of teratoma.
Histopathologic analysis revealed mature tissues, cartilage tissue and sebaceous material with the mass. A: Lower magnification (40 ×, scale bar = 250 μm) shows cartilage tissue; B: Loupe image of the tumor shows mature tissues (100 ×, scale bar = 100 μm); C: Higher magnification (200 ×, scale bar = 33 μm) shows sebaceous material.
Mature teratomas comprise the vast majority of all histological types of germ cell tumors, which predominantly originate from the gonads. Extragonadal germ cell tumors are found in the mediastinum, peritoneum, sacral pineal gland, thyroid, and gastrointestinal tract, of which the anterior mediastinum is the most frequent extragonadal site and these tumors are named mediastinal teratomas. Mediastinal teratoma should be differentiated from a series of thoracic tumors, including mediastinal lymphomas, thymomas, esophageal cysts, bronchogenic cysts, pericardial tumors, lymphangiomas, neurogenic tumors, and mesenchymal tumors.
The majority of mediastinal teratomas are benign, which means the tumors grow quite slowly and are almost asymptomatic in the early stages. Few cases of rapidly growing mediastinal mature teratomas have been published. Thus, most of these tumors were diagnosed incidentally during medical examination. However, the specific mechanism of action of mediastinal mature teratoma development is unclear. It is documented that tumors which proliferated and grew to a certain extent could induce extrinsic compression of adjacent vital structures, which results in representative clinical symptoms including chest congestion, bronchial cough, blood-streaked phlegm, hemoptysis, as well as dyspnea. Moreover, the tumors can also rupture into adjacent structures, such as the pericardium, bronchus, and pleural space, where sebaceous materials or hair can be observed by electric bronchoscope or fine needle aspiration biopsy. As an extreme example, a case report illustrated a mature mediastinal teratoma with complex rupture into the skin with a cysto-cutaneous fistula, which produced sebum and hair. Some teratomas contain malignant components, indicating that radiotherapy and chemotherapy may be acceptable management options.
In clinical practice, the most effective diagnostic modality for mediastinal teratomas is CT, which provides unambiguous signs of tumor rupture as well as infiltration of adjacent structures, crucial for early diagnosis and surgical decisions.
Surgical resection is the mainstay of teratoma treatment, particularly for mature teratomas. The choice of surgical approach for mediastinal teratomas depends to a large extent on the size, location, invasiveness, histological classification, metastases, the relationship of the tumor to the relevant vital structures, as well as the experience of the surgeon. Traditionally, a lateral, anterolateral or median sternotomy is the primary approach for resecting teratomas. Moreover, robotic surgery and VATS-assisted surgery are increasingly used in the surgical excision of mediastinal tumors. In recent years, the application of VATS has played an important role in thymectomy, which also provides the rational for teratoma resection[6,14]. However, there are few reports on the application of VATS to resect mediastinal teratomas. There are always extensive and widespread adhesions between mediastinal teratomas and adjacent vital organs and tissues. In addition, some teratomas are also inflamed, infiltrated, and ruptured. Therefore, great care must be taken during resection of the tumor. Serious cardiopulmonary complications, such as hemorrhage, cardiac arrest, and diaphragmatic paralysis, may occur when adjacent vital structures are damaged. In addition, some anesthesia-related problems may occur during mediastinal tumor excision due to adjacent structures such as the superior vena cava. For example, Kumar et al reported a case of intraoperative catastrophe during benign mediastinal tumor mass excision, which demonstrated that adequate preoperative assessment, as well as standby extracorporeal circulatory support is critical for successful management. In the present case, we successfully applied the UniVATS technique to resect a large infiltrating mediastinal teratoma with a significant degree of structural and functional preservation of the adjacent tissues and organs.