[Case of Primary Mediastinal Non-Seminomatous Germ Cell Tumor with Pathological Complete Response after Induction Chemotherapy and Residual Tumor Resection Accompanied by Late-Onset Bilateral Pneumothorax].

A man in his late teens presented to our hospital with left-sided chest pain. CT showed a 12 cm sized anterior mediastinal tumor and tiny nodules in the bilateral lower lobe of the lungs. The patient also had elevated serum AFP and hCG levels. Pathological findings of the CT-guided biopsy specimen suggested a yolk sac tumor, and no testicular abnormality was seen on ultrasound. Following whole body examination, he was diagnosed with primary mediastinal non-seminomatous germ cell tumor. After sperm cryopreservation, 4 courses of BEP(bleomycin[BLM]plus etoposide[ETP]plus cisplatin[CDDP]) chemotherapy were administered to normalize the tumor markers. The mediastinal tumor shrank but was still widely in contact with the left pulmonary artery. He underwent mediastinal tumor resection and segmentectomy of the left upper lobe via a median sternotomy. The maximum tumor size was 9 cm in diameter, and pathological examination of the specimen revealed only an immature teratoma with no malignant findings. At the same time, both the lower lung nodules were resected and pathologically identified as intrapulmonary lymph nodes. No recurrence was observed, but 6 months after surgery, he made an emergency visit to our department due to dyspnea. Bilateral pneumothorax was detected, and chest tube insertion was rapidly performed that improved with only right chest drainage. Cytology of the right hemorrhagic pleural effusion showed no evidence of malignancy. It was possible that a postoperative right-to-left shunt of the anterior mediastinum was present, leading to bilateral pneumothorax.