Abstract PS2-01-09: The Structural Mastectomy: Application of circum-mammary ligament preservation in nipple-sparing mastectomy

Abstract Background: The anatomic boundaries of conventional nipple-sparing mastectomy (NSM) is poorly defined. As such, deeper support structures, such as the circummammary ligament, the anterior lamellar fascia, and adjacent perforators, lymphatics and nerves are disrupted, compromising perfusion, wound healing, and reconstructive outcomes. The structural mastectomy preserves these structures to enhance perfusion, reduce complications, and facilitate direct-to-implant (DTI) reconstruction without acellular dermal matrices in the prepectoral plane. This study evaluates reconstructive outcomes associated with structural versus conventional NSM with immediate DTI reconstruction. Methods: A retrospective review was conducted of all patients who underwent NSM with DTI reconstruction at a single institution between November 2020 and July 2024. Patients were stratified by mastectomy technique into those who received a structural NSM (s-NSM) and those who underwent conventional non-structural NSM. s-NSM was characterized by the preservation of the circummammary ligament, superficial fascial system, and associated neurovascular bundles through dissection along well-visualized planes through a 6 cm incision. Primary outcome was short-term (≤30 days) and long-term (>30 days) reconstructive complications. Results: A total of 122 patients (225 breasts) underwent conventional NSM (135 breasts, 60.0%) or s-NSM (90 breasts, 40.0%) with immediate DTI reconstruction. Baseline demographics, comorbidity profiles, and oncologic indications were similar between groups. Compared with conventional NSM, s-NSM was associated with shorter operative time (p=0.002), lower ADM use (55.6% vs. 94.1%, p