A reconstructive breast prosthesis suitable for implantation into a void in a breast following a lumpectomy procedure in which a body of tissue is excised from the breast, the reconstructive breast prosthesis including an implant body at least generally configured to assume an implant shape corresponding to the shape of the body of tissue excised from the breast and an implant shape retaining structure adapted to maintain the implant body in the implant shape, the reconstructive breast prosthesis having an overall density which is less than the density of the body of tissue excised from the breast.