Giant mediastinal mature cystic teratoma| Rassegna di Patologia dell'Apparato Respiratorio

Abstract

A 44-year-old lifelong nonsmoker woman with progressive dyspnoea on exertion, dry cough, and morning neck swelling was referred to our Pulmonary Unit at GB Morgagni Hospital, Forlì, Italy. Initial chest X-ray revealed a significantly enlarged mediastinum with an extensive bilobed opacity. The CT scan of the chest confirmed the presence of an anterior mediastinal mass compressing numerous mediastinal organs. The patient underwent thoracotomy, which allowed for the removal of the mass measuring 23×21×13 cm. The mass was diagnosed as mediastinal mature cystic teratoma.

Case report

A 44-year-old Caucasian woman presented to the pulmonary clinic with a two-month history of progressive dyspnoea on exertion, dry cough, and neck swelling in the morning over the past two weeks. She was a never-smoker with no significant family history. Her past medical history was unremarkable, and she did not take regular medications. Physical examination revealed a normal blood pressure (125/75 mmHg), heart rate of 72 beats per minute, respiratory rate of 14 breaths per minute, and oxygen saturation of 96% while breathing room air at rest. Chest auscultation showed reduced breath sounds in the upper right lung and the mid-fields of both lung. Laboratory findings, including alpha-fetoprotein and beta-hCG levels, were within normal limits. Chest radiography showed a markedly enlarged mediastinum due to the presence of extensive bilobed opacity (Fig. 1). The lesion filled the entire anterior mediastinum and did not show a silhouette sign at the right margin of the heart, allowing for the exclusion of pathologies originating from the pulmonary parenchyma, as the normal borders between structures of different densities, such as the heart and pulmonary parenchyma, are preserved. Complete opacification due to atelectasis was observed in the right upper lobe. Subsequent computed tomography imaging of the chest revealed a large heterogeneous anterior mediastinal mass measuring 23×21×13 cm. The mass exhibited mixed density, incorporating calcification, soft tissue, and fat, encompassing the trachea, main bronchi, right atrium, right ventricle, pulmonary trunk, and superior vena cava (Fig. 2). Bilateral clamshell thoracotomy was required for complete resection of the massive lesion and restoration of mediastinal integrity (Figs. 3-4). Postoperative recovery was uneventful, with the patient discharged after one week. A final diagnosis of giant mediastinal mature cystic teratoma, the most common extra-gonadal germ cell tumor (GCT), was established. At the one-year follow-up, the patient’s clinical status was excellent.

Discussion

Anterior mediastinal masses are relatively uncommon and encompass a wide range of entities, often posing a diagnostic challenge for clinicians. The differential diagnosis includes thymic tumors, germ cell tumors, thyroid lesions, and lymphoproliferative disorders, which are the most common malignant neoplasms involving the mediastinum. However, in the appropriate context, the set of clinical data such as age, sex, hematologic tests, and radiological characteristics allow for reaching a presumptive diagnosis of the lesion. GCTs are neoplasms of pluripotent germ cell origin; they usually are well-circumscribed heterogeneous masses, mostly benign and usually asymptomatic due to their slow growth ¹. Mediastinal GCTs originate from germ cells that are incorrectly retained during their migration along the midline during embryonic development ². The treatment is surgical, involving the complete resection of the mass, with an excellent prognosis. Traditionally, large teratomas have been resected using an open approach; however, there is an increasing trend toward the use of video-assisted thoracoscopic surgery (VATS) for resection, as it is less invasive and reduces hospital stay.

In conclusion, this clinical imaging case is highly illustrative, as despite a massive mediastinal mass, the patient may remain largely asymptomatic until adjacent anatomical structures are affected by compressive phenomena.

History

Ricevuto/Received: 04/06/2024

Accettato/Accepted: 06/11/2024

Figure e tabelle

Figure 1.Chest X-ray demonstrates an enlarged mediastinum due to the presence of extensive bilobed opacity.

Figure 2.CT scan showing the large mass with mixed density encompassing the trachea, main bronchi, right atrium, right ventricle, pulmonary trunk, and superior vena cava.

Figure 3.Chest X-ray showing complete restoration of the mediastinum after one-week of surgery.

Figure 4.Giant mediastinal mature cystic teratoma.

Riferimenti bibliografici

1. Fichtner A, Marx A, Ströbel P. Primary germ cell tumours of the mediastinum: A review with emphasis on diagnostic challenges. Histopathology. 2024; 84:216-237. DOI
2. El-Zaatari ZM, Ro JY. Mediastinal germ cell tumors: a review and update on pathologic, clinical, and molecular features. Adv Anat Pathol. 2021; 28:335-350. DOI