Background <p>Dedifferentiated liposarcomas of mediastinal origin are rare. They are prone to local recurrence and distant metastases; therefore, complete surgical resection is desirable and the most important prognostic factor. In this report, we describe a case of dedifferentiated liposarcoma involving the aortic arch, left common carotid artery, and left subclavian artery that was successfully resected via total arch replacement.</p> Case presentation <p>A 78-year-old man presenting with hoarseness was diagnosed with a mediastinal tumor. After the examination, the tumor was suspected to be malignant, and the patient was referred to our hospital for surgery. We elected to remove the tumor using an artificial vessel replacement in the aortic arch. The surgery was performed, and the patient’s postoperative course was uneventful. The patient was discharged 26&#xa0;days postoperatively. He is currently being followed up on an outpatient basis, with no signs of recurrence.</p> Conclusions <p>We encountered a case of dedifferentiated liposarcoma involving the aortic arch, left common carotid artery, and left subclavian artery. Careful planning of the surgical procedures and complete resection of the tumor are important for successful outcomes in such cases.</p>