A Case of Metachronous Testicular Tumor Developing Twenty Years after Treatment of Retroperitoneal Extragonadal Germ Cell Tumor

A 49-year-old male visited our department of gastroenterology with chief complaints of blackish feces and ill complexion in February 1997. Computed tomography (CT) revealed a right retroperitoneal tumor, which was removed the same month. Histopathological examination showed teratoma and yolk sac tumor. He was diagnosed with primary retroperitoneal extragonadal germ cell tumor, and received three cycles of chemotherapy (bleomycin/etoposide/cisplatin ; BEP) starting in March 1997. Periodic imaging and determination of tumor markers (α fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase) showed no recurrence or metastasis for five years after treatment. After his visit in April 2002 he stopped visiting our outpatient ward. In November 2017, the patient visited our department with chief complaints of indolent right scrotum enlargement and a right inguinal mass. Past history showed that he had undergone hydrocele of the right testicle in August 1999. Contrast enhanced CT showed a 35-mm contrast effect with uneven contents in the right testis, and enlarged nodes that were suspicious of metastases in the right inguinal and right external iliac lymph nodes. All tumor markers were within the normal ranges. He underwent right high orchiectomy and resection of the right inguinal lymph nodes in the same month. Histopathological findings revealed seminoma (pT1, pN2, M0, S0, and clinical Stage IIA). He received postoperative chemotherapy starting in January 2018 ; one cycle of BEP therapy and three cycles of etoposide and cisplatin (EP) therapy. Post-chemotherapeutic CT confirmed clinical complete response at the right external iliac lymph nodes, and this response was confirmed 12 months later. Neither recurrence nor metastasis has occurred so far.