Extragonadal Seminoma: Simultaneous Involvement of the Anterior Mediastinum and Central Nervous System.

We report a case of a 20-year-old male who presented with a two-month history of progressively worsening binocular diplopia, dizziness, chest tightness, and significant weight gain. A comprehensive evaluation, including serial imaging, biopsy, and cerebrospinal fluid analysis, ultimately led to the diagnosis of an extragonadal seminoma with simultaneous involvement of the anterior mediastinum and the brain. Notably, the patient had a longstanding history of nonspecific testicular microlithiasis. The patient exhibited a favorable clinical and radiological response to treatment with whole-brain radiation combined with BEP (cisplatin, etoposide, bleomycin) chemotherapy. This rare presentation, together with the positive therapeutic outcome, provides meaningful insights into the existing literature on extragonadal germ cell tumors, particularly regarding atypical metastatic patterns, diagnostic challenges, therapeutic considerations, and prognosis in complex clinical scenarios.