What Is Modified Radical Mastectomy? MRM doesn’t remove chest muscles like a traditional radical mastectomy does. During the procedure, the surgeon removes the breast, including the skin, breast tissue, areola, and nipple, and most of the lymph nodes under the arm. The lining over the large muscle in the chest is also removed, but the muscle itself is left in place.
Simple mastectomy and modified radical mastectomy. A simple mastectomy (left) removes the breast tissue, nipple, areola and skin but not all the lymph nodes. A modified radical mastectomy (right) removes the entire breast — including the breast tissue, skin, areola and nipple — and most of the underarm (axillary) lymph nodes.