Elective video-assisted thoracic surgery for a ruptured mature mediastinal teratoma: A case report

Abstract

Introduction and importance

Mature mediastinal teratomas can rarely become symptomatic after a compression of surrounding organs and a rupture and are often treated with an emergency open approach such as median sternotomy. Clinical significance of thoracoscopic approach as elective setting is unknown.

Case presentation

A previously healthy 21-year-old man presented with worsening left-sided chest pain for one week. Chest computed tomography revealed a multilocular cystic mass with no evidence of great vessel invasion. A histopathological examination of the biopsy specimen revealed that the pancreatic glands and ductal elements were without any immature embryonic tissue, consistent with a mature teratoma. After the symptoms improved, he successfully underwent an elective video-assisted thoracic surgery as a substitute for an emergency median sternotomy.

Clinical discussion

The ectopic pancreatic tissue itself may not imply an emergency surgery and a comprehensive workup is essential for an optimal treatment strategy. Elective surgery is worthy of consideration as a therapeutic option.

Conclusion

Elective video-assisted thoracic surgery could be a feasible option even for a ruptured mature mediastinal teratoma in selected patients. Besides its maximum size, a large proportion of the cystic component and the absence of great vessel invasion may indicate the feasibility of a video-assisted thoracic surgery.

Highlights

• •Mature mediastinal teratomas (MMTs) can rarely become symptomatic after a rupture.
• •Ruptured MMTs are often treated in the emergency setting and a median sternotomy is the most frequent approach.
• •Elective video-assisted thoracic surgery could be a feasible option even for ruptured MMTs in selected patients.

1. Introduction

Mature mediastinal teratomas (MMTs) are one of the most common germ cell tumors (GCTs) developing in the anterior mediastinum [1]. Most cases are latent but rarely could become symptomatic after a compression of surrounding organs and a rupture for which an emergency open approach such as median sternotomy is frequently chosen [2]^, [3]^, [4]^, [5]^, [6]. We herein report a case of a ruptured MMT successfully removed by an elective video-assisted thoracic surgery (VATS). This work has been reported in line with the SCARE criteria [7].

2. Presentation of case

A previously healthy 21-year-old man presented with worsening left-sided chest pain for one week. He also had a fever with leukocytosis and an elevated C-reactive protein level. A chest radiograph revealed a homogeneous opacity in the left lower lung field with a blunt costophrenic angle (Fig. 1). Chest computed tomography (CT) revealed a multilocular cystic mass approximately 7.3 cm ∗ 8.2 cm∗ 11.0 cm in size with a left pleural effusion (Fig. 2A). The mass extended along the pericardium, suggesting left phrenic nerve involvement with no evidence of a great vessel invasion. Magnetic resonance imaging confirmed a high-intensity mass on the T2-weighted images and a low-intensity area on the fat-suppressed imaging, suggesting the presence of adipose tissue (Fig. 2B).

Fig. 1.

A chest radiograph on admission showing a large mass in the left hemithorax.

Fig. 2.

A: A chest CT showing a polycystic mass extending along the pericardium with no evidence of great vessel invasion.

B: T2-weighted image showing a heterogenous high-intensity area, suggesting adipose tissue inside (arrow).

He had no testicular abnormalities and normal serum alpha-fetoprotein and human-chorionic-gonadotropin levels. A CT-guided biopsy was performed and a histopathological examination revealed that the pancreatic glands and ductal elements without immature embryonic tissue, consistent with a mature teratoma (Fig. 3).

Fig. 3.

A: Histopathological examination of the biopsy specimen revealed pancreatic acinar-like cells with ductal structures (scale bar: 500 μm).

B: Pancreatic acinar cells were confirmed by the positive immunostaining for trypsin (scale bar: 200 μm).

Elective surgery was planned because of his improving symptoms 4 days after the administration of Sulbactam Sodium and Ampicillin Sodium 12 g per day. We proposed an elective VATS as a substitute for an upfront median sternotomy because of the lack of great vessel invasion. In addition, the preceding right-sided approach was mandatory because the chest CT had strongly suggested left phrenic nerve involvement and contralateral nerve preservation was essential.

With the patient in the supine position, a thoracoscopic view from the third intercostal space of the right anterior axillary line confirmed no involvement of the right phrenic nerve. The thymic tissue was dissected from the pericardium towards the left hemithorax, and the right phrenic nerve was totally preserved (Fig. 4A).

Fig. 4.

A: The thoracoscopic view from the right side revealed the dissected thymic tissue (arrows) preserving the right phrenic nerve (arrow heads).

B: The thymic tissue and mediastinal mass (arrows) were completely removed from the pericardium into the left thoracic cavity.

A subsequent left exploratory thoracoscopy revealed a distended mediastinal mass involving the left phrenic nerve without any adhesions to other surrounding organs (Fig. 4B). A total thymectomy and combined resection of the left phrenic nerve was completed thoracoscopically with a 316-min operation time, and the intraoperative blood loss was 10 ml. The excised specimen was retrieved in a surgical bag from the left fifth intercostal space with a 12 cm skin incision.

The histopathological findings revealed that the inner cavity of the cystic wall was lined by epithelial cells such as squamous and ciliated columnar epithelial cells. There was diffuse pancreatic tissue in the surrounding stroma without any inflammatory changes or any immature components (Fig. 5). The amylase activity of the pleural effusion was normal at 38 U/l. The postoperative course was uneventful and the patient was discharged 5 days after surgery.

Fig. 5.

A: Cartilage and adipose tissue without immature components were also seen (scale bar: 500 μm).

B: Histopathological examination of the surgical specimen revealed keratinizing squamous epithelium and skin appendages (scale bar: 500 μm).

3. Discussion

MMTs are the most common extragonadal germ cell tumor composed of well-differentiated elements of several germinal layers [8]. Most cases are latent but could become symptomatic by compression of the surrounding organs and rarely after a rupture[2]^, [3]^, [9]^, [10]. Because malignancies such as a seminoma or non-seminomatous GCT should also be raised as a differential diagnosis of anterior mediastinal tumor in young adult males even with a normal serum tumor marker level, a CT-guided biopsy was essential in the present case [1]^, [11].

A median sternotomy is the conventional standard surgical approach for anterior mediastinal tumors including ruptured MMTs [12]^, [13]. Recent advances in endoscopic surgery have promoted the VATS approach and achieve better surgical outcomes with less morbidity, and the conventional eligibility includes the maximum tumor size and absence of vascular invasions [14]^, [15]^, [16]^, [17]. Besides its maximum size, its cystic component diameter has also been proven to be a significant eligibility criterion [15]. The tumor in the present case was larger than 10 cm and contained a 5.9 cm-long cystic component inside that was successfully removed via VATS. Those results suggest that the VATS approach might be feasible even for ruptured MMTs in selected patients. The bilateral approach in the supine position also plays an important role to identify left phrenic nerve involvement and also to preserve the contralateral nerve in advance [18].

Ruptured MMTs are often treated in the emergency setting mainly due to their sudden onset [19]. Pancreatic tissue, one of the most frequent contents of MMTs, may also raise the concern of inflammation due to pancreatic secretion [3]. However, ectopic pancreatic tissue alone would not routinely be activated enzymatically because of the absence of gastric acid or cholecystokinin without parasympathetic nerve stimulation, and several hypotheses for the mechanism of a rupture other than autolysis due to digestive enzymes have been reported [3]^, [20]. There was no inflammation or necrosis in the resected specimen, and the amylase activity of the pleural effusion was normal in the present case. Those results suggested that emergency surgery can be avoided in selected patients with a ruptured MMT even in the presence of ectopic pancreatic tissue.

4. Conclusion

Elective VATS could be a feasible option even for a ruptured MMT in selected patients. Besides its maximum size, a large proportion of the cystic component and the absence of great vessel invasion may indicate the feasibility of VATS. Ectopic pancreatic tissue itself may not imply emergency surgery, and a comprehensive workup is essential for an optimal treatment strategy.

Ethics approval and consent to participate

Ethical Approval was waived by the authors institution.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

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Guarantor

Toru Nakamura.

CRediT authorship contribution statement

MW wrote this paper. All authors read and approved the final manuscript.

Declaration of competing interest

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