Testicular teratoma and primary retroperitoneal choriocarcinoma with lung metastasis: a case report.

Background: Male primary retroperitoneal choriocarcinoma (PRC) is rare with poor prognosis. No literature reports co-occurrence of testicular teratoma and PRC diagnosed after puberty. Case Description: A 23-year-old man presented pain in the right lower abdomen for 11 days without any other symptoms. He claimed he was not a smoker and had no history of any disease. Physical examination found his pain got worse in supine position. Laboratory testing found white blood cell count of 11.0×10 Conclusions: This is the first study that has reported such a rare co-occurrence of male PRC with lung metastasis and testicular mature teratoma diagnosed after puberty. Surgery is the first choice for this case. A thorough evaluation of the retroperitoneal tumor before surgery is critical for the surgeon to pick an appropriate operation program. Immunochemical markers can provide some evidence for the subsequent treatment and prognosis prediction. Very poor prognosis with only 11-month survival time is predicted by both tumors having high percentage of Ki-67 +, the retroperitoneal tumor having vascular and neural invasiveness with lung metastasis, and high malignancy of male PRC at the late stage.