A 59-year-old female patient visited our oral and maxillofacial department clinic complaining of a sense of discomfort in the right posterior palatal area. The patient did not remember exactly when the symptom began. The patient had no other concerned medical history. On clinical examination, a dome-shaped mass of 2.0 × 2.5 × 1.0 cm with clear border and no ulceration was observed in the right posterior palatal area. On the next days of admission, incisional biopsy was performed under local anesthesia. Pleomorphic adenoma (with central coagulative necrosis, most likely traumatized pleomorphic adenoma) was reported histopathologically. Hence, the patient underwent simple mass excision with safety margin under general anesthesia without any additional examination. Postoperative histopathologic report was epithelial myoepithelial carcinoma with positive basal resection margin. Magnetic resonance imaging of the head and neck and whole-body positron emission tomography were performed for further examination, but there was no evidence of distant metastasis (pT2N0M0, stage II) that was shown. Postoperative radiation therapy was administered to the primary site at the Department of Radiation Oncology, and the total radiation dose was 6148, 5400, and 4500 cGy at the operation site, border area, and lateral cervical lymph node level IB and II, respectively, for 39 days. There were no significant complications other than oral mucositis. After radiation therapy, a 1.5 × 1.0 cm fistula occurred in the right site, which was the operated site, and a fistula closure was done using two-flap palatoplasty under general anesthesia at 8 months after radiation therapy. However, the operated right side flap, which had poor blood circulation after radiation therapy, was necrotized. We removed the necrotized flap under general anesthesia and designed a facial artery myomucosal island flap containing the right mucosal membrane and buccinators, using the facial artery as a trophic blood supply to the flap. The flap was transposed by tunneling to restore the defect through the lingual side of the mandible. The donor was restored using the ipsilateral buccal fat pad flap. After the operation, the nasal and oral opening was closed and properly healed up.