An autopsy case of primary mixed choriocarcinoma and mature teratoma located in the thymic region associated with elevated human chorionic gonadotropin levels and characteristic testicular changes

An autopsy case of a 19-year-old male Japanese student with a primary mixed choriocarcinoma and mature teratoma in the thymic region is reported. The patient died 7 days after he first noticed fever and dyspnea. On autopsy, an anterior mediastinal mass was found to be in contact with the thymic gland. The mass weighed 270 g and measured 12.5 cm × 10 cm × 5 cm. The left thoracic cavity contained 2200 ml bloody pleural effusion and 200 g coagula due to hemorrhage from the tumor. Metastasized choriocarcinoma was seen in both lungs and the liver. High serum levels of human chorionic gonadotropin (HCG, 1 634 000 mIU/ml) and a decreased weight of the testes (2.0 g each) with Leydig cell hyperplasia/hypertrophy and the seminiferous tubules with hyaline ghost tubules or Sertoli cell only tubules were seen; other male reproductive organs were histologically normal. Although the serum testosterone level was within the normal range (5.75 ng/ml), luteinizing hormone (LH, 0.1 mIU/ml) and follicle-stimulating hormone (FSH, 0.3 mIU/ml) levels were decreased. High serum levels of HCG and characteristic testicular changes are drscribed.