Typically, a “lazy S” incision is used along the pectoralis major muscle, extending posteriorly at the level of the axillary hair line, and then inferiorly along the latissimus dorsi muscle (FIG 3). For patients with a prior excisional or SLN biopsy incision, this should be encompassed into the ALND incision, and thus might impact the choice of incision. For patients with bulky adenopathy, particularly those with nodes close to the skin, the skin overlying the nodes should be included with the specimen. Be sure there is adequate skin to allow for a tension-free closure.

After incising the skin with a scalpel, electrocautery is used to divide the subcutaneous tissue and elevate skin
flaps. Unless mandated by the presence of bulky disease, the skin flaps should not be too thin and get progressively thicker as they are raised. Thin skin flaps will increase the risk of wound complications and give the axilla a sunken-in appearance.

The skin is elevated using skin hooks or sharp rakes. It is important that the surgical assistant holds the flaps straight up and not retract them back (which residents will sometimes do in order to get a better view). The surgeon retracts the tissue with the opposite hand in order to apply strong countertraction and identify the appropriate tissue plane.

Surgeons are often hesitant to go too far or too deep while elevating the inferior skin flap at this initial point of the operation for fear of injuring the long thoracic nerve. However, raising an adequate inferior flap allows for greater mobility of the specimen and easier dissection. The inferior flap should be raised to approximately the level of the 5th rib.

Once the flaps are elevated, the next step will be to identify some of the borders of the axilla: the pectoralis major and minor muscles, the latissimus dorsi muscle, and the axillary vein. Although individual surgeons have their preferences, there is no correct order, and the presence of large lymph nodes might mandate changing your approach. In this chapter, we will describe a medialto-lateral approach.

The pectoralis major muscle is usually the easiest margin to begin with, as it is often easily palpable upon raising the flaps (and may become apparent while elevating the superior flap). Once the pectoralis major is identified, the length of the lateral border should be exposed (FIG 4).

Once the pectoralis major muscle is freed, it is retracted anteriorly and medially to expose the interpectoral nodes and the pectoralis minor muscle. This, and the remainder of the operation, is facilitated by the use of a Thompson retractor (FIG 5).

The tissue between the pectoralis major and minor muscle that contains the interpectoral (Rotter’s) nodes is included with the specimen, dissecting it off the pectoralis minor muscle. As the dissection proceeds onto the pectoralis minor, the medial pectoral bundle can be observed coming either through or lateral to the pectoralis minor (FIG 6). This should be preserved. There is often an accompanying vein with a branch going into the specimen. This will need to be clipped, taking care not to clip the medial pectoral nerve.

For patients undergoing an ALND for a positive SLN, the pectoralis minor can be preserved. The lateral edge of the pectoralis minor muscle is freed by dividing the axillary fascia (FIG 7). The axillary fascia is an extension of the clavipectoral fascia that divides the subcutaneous fat from the axillary fat. Upon dividing the fascia, you will notice the protrusion of a more yellow, globular fat. This is the lymph node-bearing tissue that needs to be excised.

The axillary contents are now swept laterally and the pectoralis minor muscle exposed along its length. Once this is done, the Thompson retractor can be repositioned so that both the pectoralis major and minor can be retracted anteriorly.

If there is bulky adenopathy and exposure of the upper axillary lymph nodes is difficult, it may be necessary to divide the pectoralis minor muscle, and this is described subsequently.

The vein often becomes visible medially during the elevation of the pectoralis musculature. If not, its general location can be anticipated by identifying the underarm dimple at the inferior aspect of the upper arm and tracing it toward the chest wall (FIG 8). Dissection down to the vein should not be performed directly with cautery to avoid an inadvertent injury, but rather, a careful dissection is recommended (FIG 9). Small venous branches and lymphatics should be clipped or suture ligated. It is also important not to find yourself superior to the vein, as the axillary artery and brachial plexus can be injured. Once the vein has been identified, the inferior margin should be cleared. It is not necessary to skeletonize the vein.