The operation is performed under general anesthesia. After the initial intubation, muscle relaxants are avoided so that nerve function can be assessed. Position the patient supine with the ipsilateral arm extended on an arm board (Fig. 18.1A). If necessary, place a small, folded sheet under the shoulder to improve exposure. Avoid hyperextending the shoulder because this can cause neurapraxia. Some surgeons routinely drape the arm free so that it can be moved during the course of the dissection.

The choice of incision depends on several factors, including the location of the lesion, any prior biopsy incisions, and planned reconstruction. When immediate reconstruction is to be performed, design the skin incision in consultation with the plastic surgeon who will scrub in to do the reconstruction. In many cases, skin-sparing flaps can be created in such a manner as to be oncologically correct and yet provide an aesthetically pleasing outcome. See Chapter 19 for skin-sparing and nipple-areolar–sparing incisions and further details on these more complex procedures.

When delayed reconstruction is a possibility, a generally transverse incision is favored as it facilitates reconstruction. When reconstruction will not be performed, a generally oblique incision that is high at the axillary end and low medially provides excellent access. Flaps generally heal very well with this incision and the end result is a flat chest wall to which prostheses can easily be adapted.

For a standard mastectomy, the skin incision should include the nipple-areolar complex and the skin overlying the tumor, biopsy cavity, and any prior biopsy incision (Fig. 18.1B). The biopsy cavity is considered to be contaminated by the tumor cells and frequently contains gross residual disease. It must be excised in its entirety as dissection progresses. Therefore, if the biopsy is performed through an incision located at some distance from the mass, a correspondingly larger amount of skin should be sacrificed. Alternatively, an ellipse of skin around the biopsy incision may be excised separately. Do not compromise the skin incision because of the fear of difficulty in closure. A skin graft will heal well over the underlying muscle and may be used if necessary. This is rarely necessary if flaps are designed properly.

Figure 18.1C and D shows how a “lazy S” type incision provides flaps that can accommodate a variety of lesion locations, yet slide together to afford primary closure with minimal

tension. The easiest way to create the lazy S is to first outline a diamond shape around the nipple areola and tumor location, then round the corners a bit. Remember, whenever possible, to keep the skin incision low medially and high laterally. This will make it easier for the patient to conceal the scar under her clothes and will also facilitate your access to the axillary tail of the breast and any axillary nodal tissue as needed.

As the incision is closed, flaps are allowed to slide from side to side and from top to bottom as shown. The result is a flat scar that may be hidden under clothing even for some upper inner quadrant lesions.

Incise the skin and subcutaneous tissue. Visualize the breast as lying encapsulated in a separate layer of subcutaneous fat that lies 0.5 to 1 cm below the skin. Often, this layer can be defined as the skin incision is made. Place Lahey clamps on the dermal side of the upper flap and have an assistant place these under strong upward traction (Fig. 18.2A). Apply countertraction by pulling the breast tissue down and toward you strongly with a lap sponge. Avoid manipulating the breast overlying the biopsy site. Develop flaps by sharp dissection using a shaving motion with a sharp knife or electrocautery. If a knife is used, change the blades frequently. Dissection in the proper plane is surprisingly bloodless. A network of large subcutaneous veins is often visible on the underside of the flap and will be preserved if dissection progresses in the proper plane. Ligate occasional bleeders on the underside of the flap. (Use electrocautery with caution on the flap because it can burn through the thin flap to damage the overlying skin surface.) Confirm the thickness of the flap by palpation as the dissection progresses.

An alternative technique uses slightly opened Mayo scissors to develop the flaps by a push-cut technique. This is particularly useful when the skin incision is small as during skin-sparing mastectomy.

In the axilla, the skin flap will be crossed by hair follicles and apocrine glands. Divide these sharply or pass into a very slightly deeper plane to avoid these. Raise the flaps to the level of the clavicle superiorly, the midline medially, the anterior rectus sheath inferiorly, and the anterior border of the latissimus dorsi muscle laterally (Fig. 18.2B). Of these, the lateral border of the latissimus dorsi is generally the most difficult to find.

Identify this muscle by palpation of a longitudinal ridge of muscle tissue. Dissect sharply down to confirm its identity by visualizing longitudinal muscle fibers. Trace the muscle up toward the axilla. Check the upper flap for hemostasis and place a moist laparotomy pad under the flap. Place the Lahey clamps on the inferior skin incision and develop the inferior flap by the same technique. The plane between the breast and the subcutaneous tissue is frequently less well-defined inferiorly, and unless care
is taken, the inferior flap may be cut too thick. Guard against this by constant palpation of the thickness of the flap. If white fibrous tissue (breast or suspensory ligaments of the breast [Cooper ligaments]) is seen the flap is too thick and must be cut thinner.

Draw a line around the margins of the dissection by incising the fascia at the perimeter of the field with electrocautery. This will prevent your dissecting too far in any direction. Recheck both flaps for hemostasis and place warm moist lap pads under them. Take care throughout the operation not to allow the subcutaneous fat of the underside of the flaps to become exposed and desiccated.

The breast is a conical ectodermal derivative limited to superficial fascia. The base of the breast overlies the chest wall from the second rib to the sixth and from the edge of the sternum to the midaxillary line. A lateral tongue of breast tissue—the axillary tail of Spence—extends into each axilla from the otherwise conical breast. This tail sometimes passes through the deep fascia of the axilla and approaches the pectoral group of axillary lymph nodes. Superficial to the breast is the superficial layer of the superficial fascia, whereas deep into the breast is the deep layer of superficial fascia. The subcutaneous fat lobules are small and easy to differentiate from the larger fat lobules of the breast itself.