Abstract
The latissimus dorsi muscle is a commonly used donor site in breast reconstruction. Congenital absence of this muscle is rare and can present unforeseen challenges during reconstructive surgery. We reported a case of a 62-year-old woman undergoing delayed breast reconstruction postmastectomy for breast cancer, in whom the right latissimus dorsi muscle was unexpectedly absent intraoperatively. After confirming the absence, the procedure was converted to a thoracodorsal artery perforator flap, preserving vascular supply and achieving successful reconstruction. This case highlights the importance of preoperative planning and intraoperative vigilance to identify anatomical variants. Conversion to a thoracodorsal artery perforator flap is a viable alternative when the latissimus dorsi muscle is absent, ensuring safe and effective breast reconstruction.