Successful resection of invasive thymoma directly invading the superior vena cava and right atrium with a pulmonary artery tumor embolus

A man in his forties presented with facial and upper extremity edema. Chest computed tomography (CT) revealed a huge anterior mediastinal mass with a right pulmonary artery embolus, which infiltrated the lumen of the superior vena cava (SVC) and extended into the right atrium (RA). Based on CT-guided biopsy findings, we diagnosed the patient with an invasive thymoma (type B2 per the World Health Organization [WHO] classification and stage III per the Masaoka staging system). Evaluation revealed an unresectable tumor owing to infiltration of the heart, and the patient was administered chemotherapy. However, we observed a poor therapeutic effect with tumor invasion of the right ventricle, which necessitated extended thymothymomectomy including combined resection of the other infiltrated organ except the heart. Preoperative 18 F-fluorodeoxyglucose positron emission tomography revealed left pulmonary artery embolism with high tracer uptake in this vessel, and we performed pulmonary artery embolectomy of the tumor embolus. Histo-pathological evaluation of the resected specimen confirmed an invasive thymoma (type B3 and stage III) and a left pulmonary artery tumor embolus. Currently, the patient is being administered chemotherapy owing to lung metastasis. We report a case of resection of invasive thymoma directly invading SVC and RA with a pulmonary artery tumor embolus.