Sacral Ulcer after Carbon Ion Radiotherapy Reconstructed with a Superior Gluteal Artery Perforator Flap

As carbon ion radiotherapy (CIRT) was developed only recently, reports of CIRT-induced ulcers requiring plastic surgery are still rare, but the number of such cases is expected to increase. Here, we describe a case of a CIRT-induced ulcer to aid the treatment of such ulcers. An 82-year-old man had a sacral chordoma (12 × 7.5 × 7.5 cm), which extended from the fourth to fifth sacral vertebrae. He underwent CIRT (70.4 Gy). An ulcer developed 30 months after the treatment. The ulcer enlarged to 13 cm × 7 cm. Debridement, negative-pressure wound therapy, and antibiotics were used. We tried to avoid injuring the rectum and sciatic nerve, and covered the ulcer with a delayed superior gluteal artery perforator flap. Wound healing was difficult to achieve in the lower half of the flap. Further debridement was appropriate, but we considered that it was likely to cause complications. Once a post-CIRT ulcer develops, its progression and the required extent of debridement can be roughly predicted based on the radiotherapy treatment plan. In this case, the rectum and sciatic nerve were irradiated, but there were no related symptoms. Therefore, we performed surgery to preserve these structures. However, there was very thick scar tissue surrounding these structures, making debridement difficult, and the wound was slow to heal. It is desirable to use a flap with good blood flow, such as a myocutaneous flap, for covering post-CIRT ulcers.