How would you treat a patient with retroperitoneal lymphadenopathy that has been biopsy proven metastatic seminoma, who is not a candidate for orchiectomy, RPLND, or systemic therapy?  

Very unusual case, but primary seminomas can be found in sites other than the testes. Of non-testicular primary sites, the mediastinum is probably the most well-known but other sites including the retroperitoneum have been described in the literature. Various theories for how these develop include ...