CASE 18825 Published on 17.01.2025

Giant mediastinal mature teratoma in a child

Section

Paediatric radiology

Case Type

Clinical Case

Authors

Inês Matos 1, Ana Coma 2, Luis Riera 2, Marta Gonzalo 2, Élida Vasquez 2

1 Department of Radiology, Unidade Local de Saúde (ULS) Gaia/Espinho, Vila Nova de Gaia, Portugal

2 Department of Paediatric Radiology, Vall d’Hebron University Hospital, Barcelona, Spain

Patient

2 years, male

Categories
Area of Interest Paediatric, Thorax ; Imaging Technique Conventional radiography, CT, MR
Clinical History

A two-year-old male infant with a recent history of bronchopneumonia, which did not course with fever or elevated inflammatory parameters, was referred to our hospital with a history of new-onset orthopnoea, right hemithorax hypophonesis and basal crackles.

Imaging Findings

A chest radiograph (CXR) was first performed, which showed a right-sided hemithorax opacity with dense structures within it and a slight left mediastinal shift (Figure 1). A chest ultrasound (Figure 2) was next carried out to discern the presence of pleural effusion, demonstrating the presence of a heterogeneous mass occupying the right hemithorax with anechoic and hyperechoic and pleural effusion with debris.

Given these findings, a thorax CT (Figures 3a, 3b, 3c, 3d and 3e) was performed, confirming a voluminous heterogeneous anterior mediastinal mass which occupied the right hemithorax with soft tissue, bone and fat densities compatible with a mature teratoma. Tumour markers (CEA, alfa fetoprotein and b-HCG) were negative. In order to plan the surgery, an MRI and 3D CT reconstruction were also achieved (Figures 4a, 4b, 4c, 5a, 5b and 5c).

The patient had complete surgical excision (Figure 6) with no complications and an uneventful postoperative period with resolution of his symptoms.

Discussion

Mediastinal mature teratomas are the third most frequent type of tumour found in the paediatric mediastinum, after lymphoma and neurogenic tumours. These tumours develop in the mediastinum as a result of migration of foetal germ cell precursors along germinal ridges, moving from the yolk sac to paired structures along the midline [1].

Mediastinal mature teratomas tend to appear at two distinct age ranges: around two years old, as depicted in our case, and during adolescence [1].

The clinical presentation can vary widely based on the variable size of the tumour and the mass effect it causes on nearby structures, including stridor, cough, shortness of breath, and haemoptysis [2]. Mass effect can lead to atelectasis and post-obstructive pneumonia [2].

Such as in our case, persistent non-infectious respiratory symptoms in infants should prompt consideration of a mediastinal mass. Additional signs may include chest pain, orthopnoea, superior vena cava syndrome, or vague symptoms like weight loss. On the other hand, some patients are asymptomatic, with up to 60% being identified through routine CXR. A sharply defined lesion on CXR should raise suspicion of a mediastinal teratoma [1–3].

Cross-sectional imaging is crucial for both diagnosis and surgical planning. Most mediastinal mature teratomas appear as solid, lobulated and encapsulated masses arising from the prevascular space. Calcifications are seen in 25% of cases, and the combination of fat, cystic components and calcifications in an anterior mediastinal mass is suggestive of this diagnosis. Additionally, the presence of a fat-fluid level or teeth within the mass is pathognomonic of a mature teratoma, as depicted in our case [2–4].

A well-defined staging system exists for teratomas arising in gonadal structures; however, because of their infrequency, no specific staging systems have yet been described for primary germ cell tumours of the mediastinum.

Mature teratomas are composed of ectodermal, mesodermal, and/or endodermal germ cell elements, and two of three germ cell layers are required to make this diagnosis [1].

Prevascular tumours include mediastinal teratoma, thymic lesions, lymphoma and vascular anomalies, with solid masses typically representing either mediastinal mature teratoma or lymphoma. A diffuse nodular enlargement of the thymus with mass effect on nearby structures suggests lymphoma [1,2].

There is still limited data on mediastinal teratomas. As it is a rare tumour, there is not any specific work-up and treatment guidelines. As shown in several reports, early referral and treatment show good prognosis [24].

The preferred treatment is complete surgical excision, achieved by carefully separating the tumour from surrounding tissues, which may pose some difficulties such as the proximity to vital structures and the possibility of adhesions. However, it is still feasible to achieve complete excision, which provides a curative approach with minimal complications [2–4].

Patients who undergo resection of benign mature teratomas can be observed for a short period of time (36 months) postoperatively while wound healing and progression of patient activity are monitored [5].

All patient information has been fully anonymised in the manuscript and associated files.

Differential Diagnosis List
Lymphoma
Thymolipoma
Thymoma
Vascular malformations
Anterior mediastinal mature teratoma
Thyroid carcinoma
Final Diagnosis
Anterior mediastinal mature teratoma
Case information
URL: https://www.eurorad.org/case/18825
DOI: 10.35100/eurorad/case.18825
ISSN: 1563-4086
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