A case of testicular cancer with retroperitoneal lymph node metastasis of teratoma with somatic‐type malignancy 18 years after initial treatment

INTRODUCTION: In testicular cancer, late relapse of teratoma with somatic‐type malignancy is rare and associated with a poor survival. A case of retroperitoneal lymph node metastasis of teratoma with somatic‐type malignancy 18 years after initial treatment for testicular cancer is reported. CASE PRESENTATION: A 46‐year‐old man had a 15‐mm‐sized mass in the para‐aortic region 18 years after initial treatment for testicular cancer, without elevated serum alfa‐fetoprotein or human chorionic gonadotropin levels. Laparoscopic retroperitoneal lymph node dissection was performed. The pathological findings showed teratoma with somatic‐type malignancy, and the findings of primary testicular cancer reported a yolk sac tumor, not teratoma. CONCLUSION: Late relapse of teratoma with somatic‐type malignancy was resected by laparoscopic retroperitoneal lymph node dissection. Therefore, long‐term follow‐up should be considered if patients with small retroperitoneal masses did not undergo retroperitoneal lymph node dissection, and early detection and surgical resection for relapse might be effective.