Between 2 and 5% of malignant germ cell tumors in males arise at extragonadal sites. The origin of extragonadal retroperitoneal germ cell tumors remains controversial. Whether these develop primarily in the retroperitoneum or are metastases of a primary testicular tumor has long been debated. We report a 38-year-old male who presented with abdominal pain and was diagnosed with retroperitoneal seminoma. The patient gave a history of having undergone a right orchidectomy for an undescended testis via the inguinal route 10 years previously with a reported histology of benign inflammatory mass.

Between 2 and 5% of malignant germ cell tumors in males arise at extragonadal sites. The origin of extragonadal retroperitoneal germ cell tumors remains controversial. Whether these develop primarily in the retroperitoneum or are metastases of a primary testicular tumor has long been debated. We report a 38-year-old male who presented with abdominal pain and was diagnosed with retroperitoneal seminoma. The patient gave a history of having undergone a right orchidectomy for an undescended testis via the inguinal route 10 years previously with a reported histology of benign inflammatory mass.