Surgical techniques

After the skin incision was performed, skin flaps were elevated to the sternum medially to the latissimus dorsi laterally, clavicle superiorly, and costal margin inferiorly with the Bovie coagulator on the superficial fascial plane anteriorly. Skin flaps were developed along the superficial layer of superficial fascia, which results in an even flap thickness throughout the whole breast. The plane between the pectoralis major fascia and pectoralis major muscle was the posterior plane of dissection.

A skin incision followed by dissection to the sternum medially, clavicle superiorly, latissimus dorsi muscle laterally, and costal margin inferiorly. The main difference between m-NSM and c-NSM is the anterior plane of dissection, which is performed along with the breast capsule, the anterior capsule of corpus mammae. The breast parenchyma is separated from the subcutaneous fat layer by the breast capsule, representing the anatomic dissection plane. This dissection plane can maximize the preservation of the anterior lamellar fat layer, which increases the thickness of the mastectomy flap. When the tumor is close to the breast capsule, dissection above the tumor area is performed along the superficial layer of superficial fascia as in c-NSM to ensure oncological safety. The posterior dissection plane was the same as the c-NSM, which was dissected under the pectoralis major muscle fascia. Graphical illustrations of the dissection planes in both the c-NSM and m-NSM are shown in Figure 1. Regardless of the mastectomy type, sharp dissection was performed in all patients, minimizing the application of electrocautery limited to hemostasis to prevent thermal damage to the mastectomy flap. Intraoperative images of the mastectomy flap immediately after c-NSM and m-NSM are shown in Figure 2.

(A) Dissection plane in c-NSM: a dissection plane is on the superficial fascial plane, and the plane between pectoralis major fascia and muscle is a posterior plane of dissection; (B) dissection plane in m-NSM when the tumor is not close to breast capsule: anterior dissection plane is on breast capsule and posterior dissection plane is between pectoralis major fascia and muscle; (C) dissection plane in m-NSM when the tumor is in contact with the capsule of corpus mammae: anterior dissection plane is on superficial margin near the tumor which is same with c-NSM. c-NSM, conventional nipple-sparing mastectomy; m-NSM, modified nipple-sparing mastectomy.

Images show the intraoperative thickness of mastectomy flaps: (A) 42 years old patient with left breast cancer presented with c-NSM (BMI:23.61 flap thickness = 0.5 cm); (B) 39 years old patient diagnosed with right breast cancer is shown after m-NSM (BMI:25.21; flap thickness = 1.5 cm). c-NSM, conventional nipple-sparing mastectomy; m-NSM, modified nipple-sparing mastectomy.

The patients undergoing either mastectomy types were evaluated intraoperatively right after the mastectomy using ICG (Indocyanine green) angiography (Fluobeam®, Fluoptics) for the quality of perfusion before the IBR is performed.

Immediate autologous or implant-based reconstruction was performed based on the preoperative plan, depending on the desires of the patients and the availability of donor sites. A free muscle-sparing transverse rectus abdominis myocutaneous flap (MS-TRAM) or a pedicled latissimus dorsi (LD) flap was transferred as an autologous reconstruction modality, while implant-based reconstruction was performed either in a single stage using a silicone implant or staged reconstruction using a tissue expander followed by silicone implant insertion. The difference between c-NSM and m-NSM in flap thickness is shown in Figure 3 using preoperative and postoperative MRI images of the breast.

Difference in mastectomy flap thickness between c-NSM and m-NSM on MRI images: (A) preoperative MRI image of the patient with right breast cancer; (B) one-month postoperative MRI image of the same patient after c-NSM and IBR using implant; (C) preoperative MRI image of another patient with right breast cancer; (D) postoperative MRI image after m-NSM and IBR using implant at 1-month follow-up; (E) 2x image of the breast shows the flap thickness of 4.92 mm after c-NSM; (F) flap thickness was 10.23 mm after m-NSM. c-NSM, conventional Nipple Sparing Mastectomy; m-NSM, modified Nipple Sparing Mastectomy.