Mature Cystic Teratoma of Anterior Mediastinum in a Child: A Case Report and Literature Review

Abstract

Mediastinal mature cystic teratomas are rare benign germ cell tumors that predominantly affect children. Despite their low incidence, they present unique diagnostic and management challenges. Early recognition and appropriate surgical intervention are crucial for optimal outcomes. This case report aims to highlight the importance of prompt diagnosis and management of mediastinal mature cystic teratomas in pediatric patients. We present the case of a 10-year-old female patient who presented with persistent chest pain and dyspnea. Imaging studies, including a chest X-ray and contrast-enhanced chest CT scan, revealed a large, well-circumscribed anterior mediastinal mass with calcifications. The patient underwent a right thoracotomy, resulting in the excision of a 6 × 5 × 5 cm mature cystic teratoma. Histopathological examination confirmed the diagnosis. The patient had an uneventful recovery and was discharged in stable condition. Mediastinal mature cystic teratomas pose diagnostic challenges due to their nonspecific symptoms and heterogeneous imaging characteristics. Differential diagnosis includes other mediastinal masses containing fat and calcifications. Surgical excision is the preferred treatment, although complete removal can be challenging due to adhesions to neighboring structures. Close follow-up is necessary to monitor for recurrence and complications. Mediastinal mature cystic teratomas are rare tumors with variable clinical presentations. Early detection and surgical intervention are crucial for optimal outcomes. These tumors should be included in the list of differential diagnoses for mediastinal masses in pediatric patients.

Introduction

Mature teratoma is a benign germ cell tumor that is rarely found in the mediastinal region of children, accounting for approximately 1% to 5% of all mediastinal tumors. ¹ Teratomas are estimated to occur in approximately 1 in every 4000 live births worldwide. ² These teratomas are predominantly diagnosed during the second and third decades of life, with an equal distribution between males and females. ³ A mediastinal teratoma originates from pluripotent embryonic cells that differentiate into tissues representing all 3 germ cell layers. ¹ They are classified into mature solid or cystic teratoma, immature teratoma, and teratoma with malignant transformation. ⁴ Signs and symptoms of mediastinal tumors usually appear when the mass presses against nearby organs, which include dysphagia, shortness of breath, stridor, cough, and chest pain. However, the clinical manifestation of teratomas might also include nonspecific symptoms, making an early diagnosis difficult. More than 60% of patients with mediastinal masses are asymptomatic and are only discovered by chance when chest imaging is done for other medical purposes. ⁵

Herein, we present a 13-year-old girl’s case with mediastinal mature teratoma that was discovered as a result of ongoing pain and successfully treated surgically.

This case has been reported in line with Surgical CAse REport (SCARE) criteria. ⁶

Case Presentation

We present the case of a 10-year-old female patient who visited the clinic accompanied by her mother on January 10, 2024. The patient complained of persistent chest pain over the past month, which radiated to her right shoulder and worsened with breathing and exertion. She also reported experiencing dyspnea but denied having a cough, abdominal pain, or abnormal bowel movement. Upon examination, a fullness was observed over the patient’s right anterior chest wall, and breath sounds were diminished over the right hemithorax. The patient’s vital signs were as follows: temperature 36.9°C, O2 saturation 98%, heart rate 130 beats per minute, and blood pressure 116/70 mmHg.

A chest X-ray was performed, revealing the presence of a mass with calcifications. Subsequently, a contrast-enhanced chest CT scan was conducted, which showed a large, well-circumscribed anterior mediastinal mass measuring 5.3 × 6.5 × 6.8 cm in size (Figure 1). Based on these findings, our initial differential diagnosis included teratoma or thymoma.

Figure 1.

The X-ray and CT scan with contrast, showing anterior mediastinal mass (5.3 × 6.5 × 6.8 cm) and surrounding anatomical structures.

Laboratory results indicated an elevated white blood cell count of 6.3 × 10⁹/L (RI: 4.5–11.0 × 109/L), a platelet count of 321 × 10⁹/L (RI: 150–400 × 109/L), and a hemoglobin level of 12.6 g/dL (RI: female: 12.0–16.0 g/dL). Electrolyte levels were within the normal range. Serum levels of beta-human chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase were tested and found to be within normal limits.

The patient subsequently underwent a right thoracotomy via a right intercostal incision. The surgical approach involved opening the layers, revealing the presence of an anterior and posterior upper mass. Resection of the mass was performed, measuring 6 × 5 × 5 cm, and a sample was obtained for histopathological analysis (Figure 2). Additionally, a swab of the fluid within the thoracic cavity was collected. Thoracic drainage was installed, and the surgical site was closed in layers.

Figure 2.

(A) Excised mass. (B) Incision site after mass excision.

Histopathological examination of the resected tumor confirmed the diagnosis of a mature cystic teratoma (Figure 3). The patient had an uneventful postoperative recovery and was discharged in a stable condition 9 days after the surgery.

Figure 3.

A histological overview of the mass, highlighting the presence of 3 different tissue types: (1) cartilage, (2) pancreatic, and (3) adipose tissues.

Discussion

Mediastinal teratomas, uncommon congenital anomalies, are typically identified in individuals during their late second or third decade of life. ⁷ These tumors arise from multiple embryonic germ cell layers and are classified into various subtypes, including immature teratomas, teratomas with malignant transformation, and mature teratomas, which consist of fully differentiated adult tissues. ⁸ Mature teratomas are relatively uncommon, accounting for 8% to 13% of all mediastinal tumors. ⁹ Both genders are equally affected, and these tumors commonly occur in sites such as the sacrococcygeal region, ovaries, testes, brain, neck, and mediastinum. ² Because of its infrequency, understanding of germ cell tumor-associated somatic malignancies (GCTSM) in the mediastinum remains limited, as they typically emerge as secondary complications following chemotherapy and/or radiotherapy in patients initially diagnosed with malignant tumors. ¹⁰

The presentation of mediastinal benign teratomas in children typically involves an anterior mediastinal mass that appears well-circumscribed and heterogeneous on radiographic imaging, resembling multilocular cysts with calcifications and containing solid and fatty component. ⁷ As mature teratomas are benign and slow-growing, they often do not cause symptoms in 60% of cases unless they reach a size sufficient to compress adjacent structures.^4,11 However, when the tumor expands and exerts pressure on surrounding structures, symptoms such as coughing, dyspnea, dysphagia, chest discomfort, and respiratory failure may occur. ¹²

A diverse range of conditions can be considered in the differential diagnosis of a heterogeneous fat-containing mass lesion in the anterior mediastinum. When distinguishing between mature cystic teratomas and other entities such as mediastinal lipoma, mediastinal lipomatosis, thymolipoma, and liposarcoma, the presence of calcification and fluid elements is a key distinguishing factor. ¹³ Lesions arising from the thyroid or primary vascular lesions can be easily differentiated from mature cystic teratomas based on their enhanced vascularity following the administration of contrast material. Cystic or mixed solid-cystic mediastinal lesions, including cystic thymoma, lymphoma, and complex pericardial cysts, may share similar characteristics with mature teratomas. In cases where the anterior mediastinal mass exhibits solid enhancing components, lymphoma, cystic thymoma, and germ cell tumors are among the potential differential diagnoses. Utilizing cross-sectional imaging is typically essential for further differentiation and accurate diagnosis of these conditions in relation to mediastinal mature cystic teratomas.

Surgical intervention is often necessary for mature cystic teratomas due to the potential risks of complications, including skin fistulization, ¹⁴ cardiac tamponade, ¹ and malignant degeneration. ¹⁵ Chest CT remains the preferred morphological examination for assessing mature cystic teratomas. It provides valuable information regarding the tumor’s location, composition, and its relationship with adjacent structures. ¹ Typically, these tumors appear as well-defined heterogeneous masses of varying sizes, displaying a combination of cystic, solid, and fatty components. In about 20% to 40% of cases, intratumoral calcifications can also be observed. ¹⁶ In our specific case, the CT scan revealed a heterogeneous mass with a cystic component, macroscopic fat, and enhancing soft tissue density, along with noticeable coarse calcifications. Tumor marker assays, particularly α-fetoprotein and Human chorionic gonadotropin (β-HCG), are crucial as they can indicate the presence of a malignant component, such as seminomas or nonseminomatous germ cell tumors. ¹⁶ Lactate dehydrogenase levels are also evaluated in cases where lymphomas are suspected. It is worth noting that our patient’s tumor marker assays yielded normal results.

The diagnosis of mature cystic teratomas is confirmed through anatomopathological examination, which also provides valuable information about the extent of resection. ¹⁷ In cases where the resection is not complete (R1 or R2), a combination of chemotherapy, often including platins, and mediastinal radiotherapy can be considered as treatment options.

The primary treatment of choice for teratomas is surgical excision, as they tend to be well encapsulated and rarely invade neighboring structures. ¹⁷ The preferred surgical approach for optimal exposure is typically through a median sternotomy. However, in cases where the tumor is localized to a specific hemithorax, such as in our case, an anterolateral thoracotomy is often favored.^1,16 While complete removal of the tumor is generally achievable, it can be challenging due to adhesions to neighboring structures such as the thymus, pleura, and pericardium.^16,18 In some instances, endoscopic removal may be a viable option for small tumors. ¹⁶

Yasa et al ¹⁹ reported complications related to complete surgical excision, which, despite being successful, increased the risk of surgical site infection, empyema, sepsis, and death because of the large size of the tumor and its adhesion to surrounding organs. Other complications included persistent atelectasis and rupture on some area of cystic mass during difficult dissection with spoiled tumor contents material to the operation field.

Complete surgical resection is generally curative, although in cases where the teratoma exhibits malignant potential or complex interspersing among surrounding structures, additional treatments such as chemotherapy or radiation therapy may be necessary. Follow-up imaging is crucial for assessing any residual or recurrent disease as well as monitoring for postoperative complications.

In children, the postoperative prognosis for mature teratomas is typically favorable, with a survival rate surpassing 96%. ¹⁸

Long-term clinical, laboratory, and imaging surveillance is necessary for individuals who have undergone surgical removal (exeresis) of a mediastinal teratoma. This surveillance should be conducted at shorter intervals during the first 5 years after the surgery and then annually thereafter. ²⁰

Conclusion

Mediastinal teratomas are rare tumors, particularly in children, constituting a small proportion of all mediastinal tumors. Although often asymptomatic, these tumors can elicit symptoms by exerting pressure on adjacent structures. Imaging techniques, including chest X-ray and CT scan, play a crucial role in diagnosing and characterizing mediastinal teratomas. Surgical excision serves as the primary treatment approach for mature teratomas, and complete resection typically leads to a cure. The prognosis for mature teratomas in children is generally favorable, characterized by a high survival rate. This case highlights the significance of contemplating mediastinal teratomas as a potential differential diagnosis for anterior mediastinal masses, particularly in pediatric patients who present with chest pain.