We report the case of a 64-year-old woman with recurrent mediastinal dedifferentiated liposarcoma. She had undergone surgical resection twice. Subsequently, on regular follow-up visits, chest computed tomography demonstrated a third local recurrence of the tumor with invasion into adjacent intrathoracic organs. Adhesion of the heart to the anterior chest wall through a pericardial defect that had been inadvertently created at the second operation was suspected. We decided to use a thoracoabdominal approach with four-dimensional computed tomography (4DCT) for preoperative guidance. The patient had also undergone MRI; however, the result was equivocal regarding adhesion of intrathoracic organs. The use of 4DCT enabled successful en bloc resection of the tumor. Results of the pathology examination showed complete resection of a dedifferentiated liposarcoma. The patient’s postoperative course was uneventful, and she was discharged on postoperative day 19.