The regional anatomy of the breast is illustrated in Figures 1 and 2. The principal blood supply to the breast comes from the medial perforating branches of the internal mammary artery and vein after they transverse the pectoralis major muscle and its anterior investing fascia. The medial aspect of the breast has lymphatic drainage into the internal mammary chain of lymph nodes within the chest; however, this is quite variable. The majority of the lymphatics from the breast drain to the axillary lymph node basin. The most proximal node or nodes may be located in atypical locations such as within the breast in the axillary tail of the upper/outer quadrant or very low on the lateral chest wall. The identification of these nodes using radionuclide tags and blue dye localization techniques is one of the additional benefits of a sentinel lymph node dissection. Axillary lymph nodes have been classified according to three levels or areas delineated by anatomic boundaries of the pectoralis minor muscle (Figure 2). In general, level I or II nodes are removed in axillary lymph node dissections. The overall boundaries of this standard axillary lymph node dissection (ALND) are the chest wall (serratus anterior muscle) medially, the axillary vein superiorly, the subscapularis muscle plus thoracodorsal and long thoracic nerves posteriorly, and the axillary fat laterally. Level I nodes are defined as those lateral to the edge of the pectoralis minor muscle. This area includes the external mammary, subscapular, and lateral axillary nodes. Level II nodes are behind or posterior to the muscle and are commonly defined as the central axillary lymph nodes. Level III nodes are located medial or superior to the pectoralis minor muscle. This group includes the subclavicular or apical lymph nodes. They reside in the apex of the axillary space behind the clavicle and deep to the axillary vein.
The axillary vein is the major structure defining the superior border of the surgical dissection. The axillary artery (posterior and pulsatile) plus the brachial plexus (superior and solid) are palpable but not exposed. Common regional findings are dual axillary veins or a very large, long thoracic vein running longitudinally along the lateral chest. After the axillary vein is exposed by the surgeon, a key landmark aids in finding thoracodorsal nerve, which is deep upon the subscapularis muscle. A pair of subscapular veins are identified (Figure 1). The more superficial one is divided, revealing the deep subscapular vein and the adjacent subscapular artery, which may be mistaken for the thoracodorsal nerve. This nerve, however, is posterior to the axillary vein and medial to the deep subscapular vein. It tends to angle toward the deep subscapular vein, whereas the subscapular artery is more parallel. A gentle mechanical stimulation of this nerve will result in muscle contraction.
Also running parallel to the axillary vein and rising perpendicularly from between the ribs on the chest wall are the sensory intercostal brachial skin nerves. One or more of these nerves may pass directly through the axillary fat and lymph nodes that will be removed in the dissection. Division results in hypesthesia in the posterior axillary web and in the upper/inner arm. Conversely, the long thoracic nerve runs longitudinally over the serratus anterior at the depth of an axillary dissection. If the surgeon dissects the axillary fat and specimen cleanly off of the serratus anterior muscle, the long thoracic nerve will be found not on the muscle but rather out in the axillary fat about 7 or 8 cm deep to the lateral edge of the pectoralis minor muscle. Gentle mechanical stimulation will elicit contraction of the serratus anterior muscle. It is also important to note that the long thoracic nerve tends to arch anteriorly as it proceeds caudally.
The principal indication for biopsy is the presence of clinically suspicious findings on physical examination or diagnostic studies. Studies may be sampled with fine needle aspiration (FNA) and cytologic evaluation. A better diagnosis is obtained with a core-cutting biopsy and histologic study. Asymmetric nodularity, architectural distortion, or suspicious patterns of microcalcifications may require excisional biopsy guided by wire localization. In general, a wide excisional biopsy with a clear margin of several millimeters of surrounding normal glandular tissue is planned. The placement of the incision is determined by the location of the lesion (Figure 3). If possible, incisions in the upper/inner quadrants should be avoided, as they are most visible. Circumareolar or inframammary incisions tend to give the best cosmetic result. Curvilinear incisions along Langer's lines may be used in most areas; however, some surgeons prefer radial incisions, especially in the medial breast. The incision should be kept small and placed over the lesion. The incision for a wire localization need not be placed about the entrance site of the wire, because most wires are flexible enough to be drawn through the skin and subcutaneous fat into an open biopsy site.
A simple or total mastectomy is indicated in patients who are not candidates for breast-conserving (lumpectomy) operations. The principal indications are for large cancers that persist after adjuvant therapy, especially in a smaller breast, in multicentric disease, and in elderly poor-risk patients with localized lesions.
General anesthesia is given via an endotracheal tube. Short-acting muscle depolarizing agents are used for the intubation.
The patient is placed in a comfortable supine position with the arm on the involved side abducted approximately 90 degrees, in order to give maximum exposure of the region.
A routine skin prep is performed and the area is draped in a sterile manner.
A horizontal elliptical incision is inked so as to include the entire areolar complex (Figure 4). The two skin edges should be of equivalent length, as measured with a free suture between hemostats at each end. The two incisions should come together without tension.
The skin incision is made sharply with the scalpel for the depth of 1 cm or so. Any significant vessels should be secured with fine ligatures. The skin flaps are elevated with large skin hooks that are lifted vertically so as to provide countertraction as the surgeon pulls the specimen away from the skin flap. The dissection proceeds superiorly almost to the clavicle, medially to the sternal edge, and inferiorly to the costal margin near the insertion of the rectus sheath. This should include virtually all of the glandular tissue of the breast. The lateral flap dissection is carried to the edge of the pectoralis major muscle. This leaves the axillary fat and lymph nodes for a separate dissection.
A subfascial dissection is performed, lifting the breast off of the pectoralis major muscle. It is easier to begin superiorly. As the dissection continues medially, the perforating internal branches of the mammary vessel are controlled with electrocautery or ligature, using fine silk. Last, the axillary flap is developed such that the breast is removed from the lateral chest wall. The specimen is oriented for the pathologist. The wound is irrigated and careful hemostasis is obtained. The perimeter may be infiltrated with a long-acting local anesthetic. This allows the anesthesiologist to awaken the patient sooner and lessens the amount of pain medication required after surgery. Either end of the incision is retracted with single skin hooks. Scarpa's fascia and the subcutaneous fat are approximated with interrupted 000 absorbable sutures. These sutures are placed so as to serially bisect the incision, thus giving the best approximation if the two skin incisions are not of equal length. Last, a 0000 absorbable suture is placed for subcutaneous approximation of the skin. Adhesive skin strips and a dry sterile dressing complete the procedure.
The patient may use the arm immediately for normal activities. Vigorous use should be curtailed for about a week, when it is determined that the skin flaps are well sealed to the pectoralis major muscle without accumulation of serum or hematoma.
An elliptical incision is placed more obliquely, being angled toward the axilla. The entire areolar complex as well as the lesion or its biopsy scar should be included within the ellipse. If no reconstruction is planned, the wider ellipse illustrated in Figure 5 is used. After the patient is prepped and draped, the incision is marked with ink. The incisions are created to be of equal length. There should be no redundant or excess skin at either end of the incision upon closure. In overweight patients or those with very large breasts, a more lateral incision with a wider angle is required. Conversely, very creative or comma-shaped incisions that encircle only the areolar area and then proceed laterally as a single curvilinear extension to the base of the axilla may be used in coordination with the plastic surgeon, who will be performing a concurrent reconstruction (see also Plate 200, Modified Radical Mastectomy). This incision may be combined with a separate elliptical incision about a preceding biopsy site.
The full radical mastectomy is no longer included in this atlas, as most surgeons do not remove the entire pectoralis major muscle. Instead, a modified radical mastectomy is performed with a wedging out of a full-thickness section of the underlying pectoralis major muscle where the cancer is attached.