Invasive thymoma extending to the right atrium with superior vena cava syndrome presenting massive intracardiac thrombosis immediately after the start of chemotherapy: an autopsy case report.

Invasive thymomas with intraluminal tumor thrombi are rare. Removal of the thymoma and infiltration of the superior vena cava (SVC) is a curative alternative. We report an autopsy case of invasive thymoma with intraluminal growth into the intracardiac right atrium extension. Furthermore, the patient died of massive intracardiac thrombosis 5 days after the start of chemotherapy. A 66-year-old man with SVC syndrome was referred to our hospital. He had been aware of swelling of the face for 6 months. The patient was diagnosed with invasive thymoma by a CT-guided needle biopsy of the anterior mediastinal mass. Contrast-enhanced chest computed tomography showed a mass in the anterior mediastinum extending to the SVC and right atrium. As a result of discussion with surgeons and radiotherapists, we planned a multidisciplinary treatment in which neoadjuvant chemotherapy would reduce the tumor size, and surgery and postoperative radiotherapy were followed by chemotherapy. He was administered neo-adjuvant chemotherapy with CBDCA + PTX (carboplatin, area under the curve = 6, and paclitaxel, 200 mg/m2). On the 4th day of chemotherapy, he suddenly developed obstructive shock due to intracardiac thrombosis in the right ventricle. We believe that chemotherapy may trigger rapid thrombus formation. If an invasive thymoma spreads into a large vessel or the right atrium, surgical treatment should be considered if possible. However, if surgery is impossible, administration of anticoagulants should be considered to prevent thrombus formation before chemotherapy.