Summary: Adjuvant treatment planning can change after breast cancer resection and definitive pathological examination. Radiation therapy is often chosen as a supplementary treatment. Rectus abdominis–based muscle flaps are one of the main choices when breast reconstruction plans must be changed from implant-based to autologous methods. We herein report a case in which the patient’s own tissue expander capsule was used to repair an abdominal wall defect after muscle-sparing transverse rectus abdominis myocutaneous flap reconstruction.