A 71-year-old man was found to have a 7.4 × 2.9 × 7.0 cm myxofibrosarcoma of the right medial arm close to neurovascular structures. He received 50 Gray (Gy) of preoperative external beam radiation. Radical resection resulted in a 15 × 10 cm defect. Nine brachytherapy catheters were placed, and a pedicled latissimus dorsi myocutaneous flap was used in reconstruction. Final pathology confirmed myxofibrosarcoma, high grade. The tumor was <1 mm from 2 margins. A total of 17.5 Gy of brachytherapy was delivered to the surgical bed from postoperative days 7 to 9. The flap developed fat necrosis distally which eventually required surgical debridement on postoperative day 58. It subsequently healed well and maintained good function of the limb. The patient remains under surveillance without evidence of recurrence.