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

Male primary retroperitoneal choriocarcinoma (PRC) is rare with poor prognosis. No literature reports co-occurrence of testicular teratoma and PRC diagnosed after puberty.

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 11.0×10⁹/L, C-reactive protein of 40.0 mg/L, and β human chorionic gonadotropin of 5,350.27 IU/L. Ultrasound found a hypoechoic mass (0.8 cm × 0.5 cm) in the right testis. Image examinations confirmed a retroperitoneal mass (42 mm × 42 mm) bleeding with hematoma and lung metastasis. Orchiectomy and the excision of the retroperitoneal mass were done on 27 October and 3 November, 2023, respectively. Surgery helped relieve his pain and obtain the tissues for histopathology but its location made the surgery difficult to conduct. The cryopathological results of the testicular mass showed small tissues of cartilage and squamous epithelium with mature differentiation and which immunochemical markers testing showed Ki-67+ (positive), inhibin A+, vimentin+ and WT-1+. The histopathological results of the retroperitoneal mass confirmed choriocarcinoma with massive necroses and neural invasion and which immunochemical markers testing showed inhibin A+, HCG+, CK7+, CK+, Ki-67(80%+), P40(partial+), and CD34(vascular+). The patient had routine chemotherapy after surgery and followed up to his death on 27 September, 2024.

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.