Metachronous gonadal and extragonadal primary germ cell tumors: two case reports.

Bilateral synchronous or metachronous germ cell tumors (GCT) of the testis are recognized in 2-3% of patients. Extragonadal GCT in the mediastinum or the retroperitoneum have been rarely reported in patients with primary GCT of the testes. Two patients were observed with two separate primary GCT; in 1 a retroperitoneal embryonal carcinoma was successfully treated with chemotherapy and surgery and a new primary developed 14 years later in the testicle as a seminoma. A second patient had a primary teratocarcinoma of the testes treated with surgery only; 4 years later he developed a mediastinal endodermal sinus tumor, which was fatal. These cases suggest that not only is the remaining testicle at risk for a second primary GCT, but also that extragonadal sites impose a similar risk and monitoring of patients should consider all potential sites for the development of GCT.