[The extragonadal seminoma: a differential diagnosis for mediastinal growth].

The extragonadal seminoma rarely manifests as a mediastinal tumour. It is histologically similar to the testicular seminoma and is often combined with other malformations. The tumour produces signs and symptoms due to its space-occupying or infiltrating nature. Radiological methods cannot establish the diagnosis, which is performed by surgery; however, in most of the cases staging is required (thoracotomy). Treatment is possible by surgical excision, irradiation or drug therapy, with an average five-year survival rate of 75%.