A 72-year-old man presented with aggravating dyspnea and swelling of the face due to thymic carcinoma, which was diagnosed based on a transfemoral biopsy specimen. Chest computed tomography and transthoracic echocardiogram showed a mediastinal mass that invaded the superior vena cava and the right atrium. The patient underwent successful chemotherapy with multimodal regimens including cyclophosphamide, vincristine and the dyspnea, facial edema improved. Here, we present a case of spreading thymic carcinoma identified as an intraluminal growth spreading from the mediastinum into the superior vena cava and cardiac cavity.