A case of primary mediastinal choriocarcinoma involving an elderly patient who developed multiple lung metastases shortly after surgery

A 65-year-old man was referred to our hospital due to a mediastinal tumor, because chest CT revealed growth of the tumor in comparison with two years previously. CT showed a 57-mm lobulated tumor in the anterior mediastinum. Inside the tumor were cystic and marginal parts and it showed thickness of the wall with enhancement. It also showed enlargement to the surroundings and adipose tissues, but no invasion to great vessels or dissemination. FDG-PET and MRI showed similar findings. We suspected invasive thymoma or thymic cancer and performed an operation. The tumor invaded the left upper lobe and pericardium, and combined resection was performed. The pathological diagnosis was primary mediastinal choriocarcinoma. We planned adjuvant chemotherapy, but one month after surgery, chest Xp and CT showed multiple lung metastases and β-HCG was 18.67 ng/mL (