A case of squamouse cell carcinoma arising in a pectoralis major myocutaneous flap used in the oral cavity is reported.
A 64-year-old woman was treated for lower gingival squamouse cell carcinoma. After radiation therapy, radical neck dissection, mandibulectomy, total resection of oral floor, and resection of buccal mucosa and skin were performed. A PM-MC flap was used to reconstruct the defect. Six years later, recurrence in the gingiva of the maxilla was diagnosed, and the maxilla was resected partially. Eight years after the first operation, a new tumor showing papillary proliferation was noted in the center of the transplanted PM-MC flap. The tumor was simply resected and pathological examination showed that it was a well differenciated squamouse cell carcinoma in situ. In six months, a tumor was noted on the flap again. After complete resection of the tumor, there has been no recurrence for 3 years.