High-Concentration Hydrogen Peroxide Gels Containing Calcium Polyphosphate Associated With Violet Led Light: Bleaching Efficacy and Effects on Enamel Properties.

Germ cell tumors (GCTs), derived from primordial germ cells, are classified into two major groups, i.e., seminoma and non-seminoma, which differ in biological behavior, prognosis, and treatment response. Seminomas are generally highly sensitive to chemotherapy and radiation therapy and are associated with a favorable prognosis. While most GCTs arise in the gonads, a small proportion occur in extragonadal sites without an identifiable primary tumor in the testes or ovaries. These extragonadal germ cell tumors (EGGCTs) account for approximately 1-3% of all GCTs and most commonly involve the anterior mediastinum, retroperitoneum, and central nervous system []. Primary mediastinal seminomas are rare, and central nervous system involvement is even less common, usually occurring as metastatic disease. Synchronous involvement of both sites at presentation is exceedingly rare and presents diagnostic and therapeutic challenges. We report a unique case of extragonadal seminoma with concurrent involvement of the anterior mediastinum and central nervous system, highlighting the importance of recognizing atypical presentations and the need for a multidisciplinary approach to management.