Discussion

PMGCTs are rare neoplasms, accounting for less than 5% of all germ cell tumors, with the nonseminomatous subtype comprising approximately 60-70% of mediastinal cases [5]. Unlike their gonadal counterparts, NS-PMGCTs are uniformly malignant, demonstrate aggressive local behavior, and are associated with inferior outcomes. Distant metastases are present in nearly 35% of patients at diagnosis, most commonly involving the lungs, liver, and retroperitoneal lymph nodes [8], [9], underscoring their aggressive nature.

Clinical presentation is typically due to mass effect, with patients commonly reporting chest pain, cough, dyspnea, fever, or weight loss. SVC syndrome has been reported in 20-50% of NS-PMGCT cases, although it is seldom the predominant presenting feature [2]. In contrast, our patient presented with prominent venous distension and respiratory symptoms secondary to complete SVC occlusion, reflecting advanced mediastinal compression at presentation. This pattern places the current case at the severe end of the clinical spectrum described in the literature.

The diagnostic evaluation of NS-PMGCTs remains challenging due to substantial overlap with other anterior mediastinal malignancies, particularly lymphoma, thymoma, thymic carcinoma, and metastatic disease [2,8]. This complexity is further amplified by frequent tumor necrosis and poor differentiation on biopsy specimens. In the present case, initial histopathology demonstrated necro-inflammatory tissue with atypical cells, necessitating an expanded immunohistochemical panel and correlation with serum tumor markers to establish the diagnosis. Positivity for AFP and glypican-3, combined with markedly elevated serum AFP and exclusion of lymphoid and epithelial markers, was critical in confirming NS-PMGCT [10].

Tumor burden at presentation is another defining feature of NS-PMGCTs. Reported median tumor sizes range from 9 cm to 12 cm, while lesions exceeding 15 cm are uncommon but have been described [2], [5]. The mass in our patient measured 15.8 cm, placing it at the upper extreme of reported dimensions and likely accounting for the extensive local complications observed. Pericardial effusion occurs in a minority of cases, whereas progression to cardiac tamponade is rare, reported in approximately 6-7% of patients in larger series [2]. Pleural effusions are similarly infrequent and typically mild [8,9]. Unlike thrombotic SVC obstruction, malignancy-associated SVC syndrome generally requires prompt treatment of the underlying malignancy rather than anticoagulation or endovascular stenting alone. In aggressive lymphomas, early initiation of chemotherapy may rapidly relieve symptoms and improve clinical outcomes. Recognizing SVC syndrome as an oncologic emergency enables timely multidisciplinary evaluation and management.

Current treatment strategies recommend cisplatin-based combination chemotherapy as first-line treatment for NS-PMGCTs [8,9]. Although chemotherapy often results in significant tumor regression, residual masses are common and may represent fibrosis, necrosis, or persistent viable tumor. In the present case, chemotherapy achieved substantial reduction in tumor size but failed to resolve SVC obstruction, illustrating the limitations of systemic therapy in the setting of fixed vascular invasion. Surgical resection is therefore recommended for residual disease following chemotherapy, particularly when viable tumor or ongoing complications are suspected [8]. While most reported surgical interventions involve tumor excision alone, the need for segmental SVC resection with PTFE graft reconstruction under cardiopulmonary bypass, combined with extensive pericardial and pulmonary adhesiolysis, distinguishes this case as surgically complex and rarely reported in the existing literature [9].