Mediastinal seminoma in a pediatric patient managed with multi-modality treatment approach: A case report.

Abstract

Introduction

Mediastinal seminomas arise due to abnormal migration of the totipotent stem cells during development. They occur very occasionally and makes up about 0.5–5 % of all mediastinal tumors. These usually occur in middle aged men, between 20 and 40 years. In pediatric age group, it is considered as an extremely rare finding, accounting for 3 %–7 % of all primary germ cell tumors.

Case presentation

We report a rare case of a 16-year-old boy with biopsy proven seminomatous type of germ cell tumor in anterior mediastinum who presented with productive cough and progressive dyspnea. The occurrence of mediastinal seminoma especially in pediatric population is a very infrequent finding, hence, very little literature is found in this regard as per our knowledge.

Discussion

The incidence of primary mediastinal germ cell tumors is approximately around 3 %–6 % of all the germ cell tumors in pediatric population. Diagnosis of mediastinal seminomas need a multipronged approach and treatment is associated with multidisciplinary procedures including chemotherapy combined with subsequent surgical resection for long term survival benefits.

Conclusion

From the above presented case, it can be safely concluded that multimodality treatment approach of chemotherapy combined with surgical resection could ensure long-term survival benefits in extra-gonadal mediastinal seminomas.

Highlights

• •16 year old boy with progressive dyspnea
• •Biopsy proven seminomatous germ cell tumor
• •Involving left phrenic nerve and recurrent laryngeal nerve
• •Multidisciplinary treatment with chemotherapy and surgical resection

1. Introduction

Germ cell tumors have been the most predominant carcinoma in adolescent males, the primary site of origin being the testes. [1] They have been divided into two groups; seminomatous germ cell tumor and non-seminomatous germ cell tumor. [1] Primary extragonadal germ cell tumors occur very infrequently, accounting for 1–5 % of all the germ cell malignant lesions, and are usually located in the mediastinum and retroperitoneum. [2] Primary mediastinal germ cell tumor make up about 10–15 % of all the mediastinal masses. [2] Most common mediastinal germ cell tumor is mature teratoma. [3]

Mediastinal tumors in pediatric age group are a very rare finding and makes up about 6 %–25 % of all the mediastinal masses, while 3 %–7 % of all the pediatric germ cell tumors. [4] The typical presentation in patients are usually symptoms which arise due to mass effects. Tracheal compression leads to respiratory symptoms such as cough and dyspnea. Other symptoms include superior vena cava syndrome, chest pain, weight loss and heart failure. [4] The main modalities of investigation include raised serum tumor markers, such as beta-human chorionic gonadotropin hormone and alpha-fetoprotein, followed by computed tomography or magnetic resonance imaging, and assisted with histopathology for definitive diagnosis. [4]

We present a rare case of a 16-year-old boy who presented with complains of persistent cough and progressive dyspnea. He was diagnosed with biopsy proven extra-gonadal seminomatous type of germ cell tumor of the mediastinum and was referred for surgical excision of the tumor. The occurrence of such cases are very unique and little amount of literature is found regarding mediastinal seminomas to the best of our knowledge. The following case has been reported in line with the SCARE 2020 criteria [5].

2. Case report

A 16-year-old boy presented to us, with no prior comorbid conditions and no history of smoking or any addiction. He started experiencing on and off cough and progressive dyspnea for 3 years. His investigations were done. Initial Chest X-ray showed significant enlargement of the superior mediastinum with some collapse of the left upper lobe. (Fig. 1). A computed tomography scan was done which showed a large heterogenous mass measuring 150 × 120 mm identified in the anterior mediastinum, encasing the major vessels, superior vena cava, arch of aorta and descending thoracic aorta, along with trachea, left main bronchus and esophagus. No mediastinal or hilar lymphadenopathy was noted. Biopsy was done on the basis of suspicion of mediastinal tumor, and the mediastinal mass was diagnosed as extra-gonadal seminomatous germ cell tumor.

Fig. 1.

Initial Chest X-ray demonstrating large anterior mediastinal mass.

Baseline work-up was sent for staging and grading of the tumor which included serum tumor markers which revealed that serum beta human chorionic gonadotropin was markedly raised. Bone scintigraphy scan was negative. Four cycles of BEP regimen (bleomycin, etoposide, cisplatin) neoadjuvant chemotherapy were given. Repeated computed tomography scan showed a decrease in size to 36 × 69 mm. There was significant interval reduction in the soft tissue encasement of major mediastinal vessels including arch of aorta, left common carotid, subclavian arteries, superior vena cava, descending thoracic aorta. There is also significant decrease in the soft tissue surrounding the trachea and the left bronchus as well (Fig. 2). After discussion with tumor board, patient was referred to Cardiothoracic Surgery for resection/debulking surgery of the mediastinal seminoma.

Fig. 2.

Post Neoadjuvant Chemotherapy showing anterior mediastinal mass with encasement of major vessels. A: Axial view. B: Coronal view.

He underwent resection of mediastinal seminoma via median sternotomy as it gives the best exposure for the anterior mediastinum, great vessels lying in middle mediastinum and for phrenic and recurrent laryngeal nerves. Intra-operatively we found a large, very vascular tumor, firmly adherent to the pericardium and left pleura, and encasing phrenic nerve, recurrent laryngeal nerve and innominate vein. (Fig. 3A) Following median sternotomy and pericardiotomy, resection was assessed. Left lung adhesions were dissected. Aortic arch was exposed and dissected. Aorto-pulmonary area dissected. Mass was resected from mediastinum leaving tumor on the left of pericardial fold to safeguard nerves. Innominate vein and arch vessels freed from tumor. (Fig. 3B) Hemostasis was secured, drainage tubes were placed, chest closed and histopathology samples were sent. Patient was shifted in a vitally and hemodynamically stable condition. He was closely monitored for post-operative complications, and no hoarseness or left diaphragm hemiparalysis was noted. Pain was managed with analgesics and regular physiotherapy was carried out after which the condition of the patient gradually improved hence, he was discharged home as planned with early clinic follow-up.

Fig. 3.

A: Shows the mediastinal mass excised. B: Anterior mediastinum after resection of mass with no residual mass over major vessels. Blue arrow signifies aorta and black arrow signifies pulmonary artery. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Mediastinal tumor specimen biopsy showed no residual malignant germ cell tumor was noticed. A single focus of stratified squamous epithelium was revealed indicative of mature teratomous component. Rest of the findings were consistent with post-chemotherapy changes exhibiting hyalinization, necrosis and inflammation. Computed tomography scan was repeated upon follow-up which showed resolution of upper mediastinal mass with small amount of residual tissue. Central tracheobronchial tree and mediastinal great vessels were unremarkable (Fig. 4). Since the mass was not completely excised by surgical removal, hence, the remaining 2 cycles of chemotherapy was given for complete eradication of the disease. Patient was followed with repeated baselines and Beta human chorionic gonadotropin hormone which declined. He showed no signs and symptoms of disease recurrence.

Fig. 4.

Post-operative CT scan showed resolution of anterior mediastinal mass with small residual tumor in area of phrenic and left recurrent laryngeal nerves. A: Axial view. B: Coronal view.

3. Discussion

Extra-gonadal germ cell tumors, principally, primary mediastinal germ cell tumor is an extremely rare occurrence. Parini et al. in their study has reported the incidence of primary mediastinal germ cell tumors to be about 10 %–15 % of all the the tumors arising in the mediastinum. [6] While, Liello et al. has mentioned that malignant mediastinal germ cell tumors account for 1 %–4 % of mediastinal tumors. [7] Primary mediastinal germ cell tumors originate from totipotent primordial germ cells which failed to migrate during fetal development. [4] Mediastinal tumors can be divided into seminomatous and non-seminomatous germ cell tumors. [7] Primary mediastinal seminomatous germ cell tumor was first reported in 1955 by Woolner et al. [8] Primary mediastinal germ cell tumors usually arise in the third to fifth decade of life in young adult males, the most predominant site being the anterior mediastinum. [6]

A recent case report stated that at the time of diagnosis around 30 % of the patients are asymptomatic. [9] In a study carried out by Zhai et al. the three most common symptoms were chest pain (14.3 %–44 %), cough (14.3 %–38 %) and dyspnea (14.3 %–38 %). [10] Diagnosis of extra gonadal seminomatous germ cell tumor needs a multifaceted approach. [4] Serum tumor markers, such as, alpha-fetoprotein, beta human chorionic gonadotropin and lactate dehydrogenase are observed and high levels of any of these enzymes may suggest a germ cell tumor. [2] Next modality of investigation includes computed tomography or magnetic resonance imaging to aid in staging the tumor. [4] An image guided biopsy is always necessary to confirm the diagnosis and histopathological samples taken during the biopsy assist in the definitive diagnosis of the tumor. [4]

Treatment of extra-gonadal germ cell tumors requires an interdisciplinary approach between different modalities, which include chemotherapy, radiotherapy and surgical resection. [4] Huang et al. mentioned in their study that the 5-year-survival rate for primary mediastinal seminoma was over 80 %, and approximately around 50 % for non-seminomatous germ cell tumor. [3] Surgical resection of primary mediastinal germ cell tumors is the primary modality of treatment. [4] The main approaches can be via anterolateral thoracotomy, posterolateral thoracotomy or median sternotomy. [4] In the above mentioned case the tumor was approached via median sternotomy. Rivera et al. concluded in their study that surgical resection of primary mediastinal germ cell tumors is an individual prognostic factor to improve the overall survival rate. [8] Even though, chemotherapy is essential for primary malignant mediastinal germ cell tumors, surgical resection is of equal importance to increase the survival benefits. [11] Kakkar et al. mentioned in their study that the surgical resection of the tumor has an increased overall survival benefit, as it helps in removing chemotherapy resistant tumor cells, as well as the histopathological assessment helps in planning further management. [4]

The significant factor of the above described case is the rarity of occurrence of primary malignant mediastinal germ cell tumor in pediatric population. Tudor et al. in their case report mentioned that the incidence of pediatric germ cell tumors is about 2 %–3 %. [12] Another study published in 2017 concluded that primary mediastinal germ cell tumors make up about 3 %–6 % of all the germ cell tumors among patients younger than 18–years of age. [13] In a study carried out in 2019, the incidence of mediastinal germ cell tumors in pediatric age group was reported to be 6 %–25 % of all the mediastinal tumors, and about 3 %–7 % of the entire pediatric germ cell tumors. [4] Heimsburg and Battersby described that germ cell tumors make up about 17 % of all the mediastinal masses under the children of 16 years of age. [14] Seminomas comprise 50 % of the primary malignant mediastinal germ cell tumors in adults but it is a rare occurrence in the pediatric age group hence, very little literature is found regarding this to the best of our knowledge. [12]

4. Conclusion

From the above presented case it can be concluded that even though primary mediastinal seminoma has a rare occurrence in the pediatric population, it should still be considered by the clinicians in the differential diagnosis of the patients presenting with mediastinal compression symptoms. Chemotherapy is now considered the first line treatment of extra-gonadal germ cell tumors, however in order to increase the rate of survival, collaborative treatment approach, combining chemotherapy, radiotherapy and surgical resection should be considered in order to increase the survival rate of the patients and to prevent further recurrence.

Funding

None.

Ethical approval

Our case report has been exempted from Ethical Review Committee of our institute, as per policy.

Consent

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.

CRediT authorship contribution statement

• 1.Abdul Ahad Sohail: Was involved in critical review, editing and finalizing the case report.
• 2.Rida Wahab: Was involved in writing the initial draft, data collection, literature search and finalizing the case report.
• 3.Waris Ahmed: Was involved in critical review, editing and finalizing the case report.

Guarantor

Abdul Ahad Sohail.

Declaration of competing interest

N/A