Sonographically-detected impalpable testicular cancer with retroperitoneal bulky metastases: a case report

We report a case of a sonographically-detected impalpable embryonal cell carcinoma with bulky retroperitoneal metastases. A 34-year-old man, who presented with left flank pain, was presumed to have an extragonadal retroperitoneal germ cell tumor. Scrotal sonography revealed a hypoechoic lesion, 7 mm in diameter, which was histologically diagnosed as a primary embryonal cell carcinoma. Evidence suggested that the primary tumor had grown slowly, as the tumor was well encapsulated. This case suggests that some extragonadal germ cell tumors arise from a primary testicular cancers, and that successful treatment of these tumors should include consideration that they may have arisen as a primary testicular mass.