Nonpalpable testicular pure seminoma with elevated serum alpha-fetoprotein presenting with retroperitoneal metastasis: a case report.

<bold>Background: </bold>Patients with a primary pure seminoma in the testis who have elevated serum alpha-fetoprotein are rare and should be treated as patients with nonseminomatous germ cell tumors. However, nonpalpable testicular tumors in this condition have never been reported. We describe a case of nonpalpable pure testicular seminoma with elevated serum alpha-fetoprotein presenting retroperitoneal metastasis. <bold>Case Presentation: </bold>A 29-year-old Asian man was referred to our hospital with right flank pain. Computed tomography showed a mass located between his aorta and inferior vena cava, but a testicular tumor was not detected. His serum levels of lactate dehydrogenase, alpha-fetoprotein, and DUPAN-2 were high. Although no tumor or nodule was palpable in his testis, ultrasonography revealed multiple low echoic lesions in his right testicular parenchyma. He was diagnosed with right testicular cancer with retroperitoneal lymph node metastasis and underwent right high orchiectomy. A pathological examination revealed pure seminoma and no nonseminomatous components were found in the specimen. Three courses of induction systemic chemotherapy (cisplatin, etoposide, and bleomycin) normalized his serum alpha-fetoprotein and DUPAN-2 levels. Three additional courses of chemotherapy (etoposide and bleomycin) were performed, and treatment was completed with laparoscopic retroperitoneal lymph node dissection. Pathology of the dissected specimen showed fibrous and necrotic tissue with no viable cells. He is alive without recurrence 54 months after orchiectomy. <bold>Conclusions: </bold>We report a case of pure testicular seminoma with elevated serum alpha-fetoprotein and DUPAN-2 presenting retroperitoneal metastasis. We recommend an ultrasound examination of bilateral testes when large retroperitoneal tumors are detected in young men, even if a mass is not palpable in the scrotum. [ABSTRACT FROM AUTHOR]