Tylectomy literally means

Lumpectomy (sometimes known as a tylectomy, paial mastectomy, breast segmental resection or breast wide local excision) is a surgical removal of a discrete poion or "lump" of breast tissue, usually in the treatment of a malignant tumor or breast cancer. It is considered a ble breast conservation therapy, as the amount of tissue removed is limited compared to a full-breast mastectomy, and thus may have physical and emotional advantages over more disfiguring treatment. Ref: Internet