Introduction

Primary mediastinal germ cell tumors (PMGCTs) are a rare subset of extragonadal germ cell tumors, accounting for approximately 1-3% of cases, and are predominantly located in the anterior mediastinum [1]. Most cases occur in young adult males between 20 and 35 years of age and may present incidentally or with symptoms related to mass effect, including chest pain, cough, and dyspnea [1,2]. The median tumor size at diagnosis is approximately 9-12 cm [3,4]. In retrospective series, superior vena cava (SVC) obstruction has been observed in 20-50% of patients, while pericardial effusion progressing to tamponade is less common, with an incidence of approximately 6-7% [2].

There are three main categories of PMGCTs: teratomas, seminomas, and nonseminomatous germ cell tumors (NSGCTs). The International Germ Cell Cancer Collaborative Group (IGCCCG) classifies primary mediastinal NSGCTs as poor-risk tumors. NSGCTs are often associated with elevated alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (β-hCG), and lactate dehydrogenase (LDH), which can assist with diagnosis and follow-up. In contrast to gonadal germ cell tumors, PMGCTs do not have well-established environmental or lifestyle risk factors. However, nonseminomatous tumors have been associated with Klinefelter syndrome and hematologic malignancies, including acute leukemias [5].

Due to the rarity of PMGCTs and the absence of formal consensus guidelines, management is generally based on expert opinion, tumor type, disease extent, and patient presentation. Multidisciplinary treatment with neoadjuvant platinum-based chemotherapy is commonly used, followed by surgical resection or radiotherapy to eliminate residual disease [5,6]. In NSGCTs, median sternotomy or thoracotomy may be used to achieve complete resection when feasible. Despite extensive multimodal therapy, nonseminomatous tumors are associated with a poor prognosis, with a five-year overall survival of approximately 40-50% and most relapses occurring within two years of initial treatment [2,5,7]. In this report, we present the case of a 30-year-old male patient with a large anterior mediastinal germ cell tumor complicated by SVC obstruction and malignant pericardial effusion with impending cardiac tamponade, requiring neoadjuvant chemotherapy followed by complex surgical resection and SVC reconstruction.

Germ cell tumors are neoplasms that arise from primordial germ cells, which normally give rise to sperm or ova. They most commonly originate in the gonads, particularly the testes in males, but may also occur in extragonadal locations, such as the mediastinum, retroperitoneum, pineal gland, or sacrococcygeal region. PMGCTs are considered extragonadal germ cell tumors and are thought to result from abnormal migration of germ cells during embryologic development. These tumors should be distinguished from metastatic germ cell tumors, in which a primary gonadal tumor spreads to the mediastinum or other distant sites. Therefore, evaluation for a testicular or other primary gonadal lesion is important before diagnosing a PMGCT. Nonseminomatous mediastinal germ cell tumors are typically aggressive, often present with large anterior mediastinal masses, and may be associated with elevated serum tumor markers such as AFP, β-hCG, and LDH.