Latissimus dorsi flap reconstruction is a breast reconstruction procedure that uses fat, muscle, and skin from the upper back ( latissimus dorsi muscle) to rebuild the breast shape after a mastectomy. Your latissimus dorsi muscle is one of the largest muscles in your body, which is located just below your shoulder and behind your armpit. I use a large flap from this area to rebuild your chest in order to create a more natural-looking breast shape.