Anthony Visioni and Julian A. Kim

Introduction

British surgeon Sir Berkeley Moynihan stated, “Surgery of cancer is not the surgery of the organs; it is the surgery of the lymphatic system.” This statement is especially true of breast cancer and melanoma, in which specific operations are carried out to remove regional lymph node metastases. Lymph node dissection (LND) was the standard of care for staging as well as treating these patients. However, sentinel lymph node biopsy (SLNB) changed the way surgeons stage and treat both breast cancer and melanoma (see Chapter 48).

Currently, LND is rarely used as a staging procedure. Furthermore, emerging evidence indicates LND may not impact survival rate in select patients with breast cancer. However, it continues to have a role in regional treatment of cancer for melanoma and breast cancer. Typically, most patients seen for LND have had their primary tumor excised and SLNB performed, which has shown metastatic disease in lymph nodes. These patients then undergo a workup to determine whether they are free of distant metastatic disease. Patients with distant metastatic disease are usually not candidates for LND and would benefit more from systemic therapies.

Axillary Lymph Node Dissection

A thorough understanding of the anatomy of the axilla is extremely important when performing an axillary lymph node dissection (ALND). The procedure involves an extensive dissection around important neurovascular structures.

The boundaries of the axilla are the axillary vein superiorly, serratus anterior muscle and chest wall medially, subscapularis and teres minor posteriorly, latissimus dorsi laterally, and pectoralis minor and major muscles anteriorly (Fig. 49-1, A). These structures create a pyramid, with the apex positioned superiorly.

The lymph nodes of the axilla are divided into levels I, II, and III, on the basis of their anatomic location in relation to the pectoralis minor (Fig. 49-1, B). Level I nodes are lateral to the lateral edge of the pectoralis minor muscle, level II nodes are posterior to the pectoralis minor, and level III nodes are medial to the medial edge. Lymph nodes are also located between the pectoralis minor and major muscles (Rotter’s interpectoral nodes).

The patient should be positioned with the arm abducted 90 degrees. If the patient is undergoing a modified radical mastectomy, access to the axilla is gained through the mastectomy incision (see Chapter 46). Otherwise, a curvilinear incision at the inferior margin of the axillary hairline is typically used (Fig. 49-2, A). If present, a scar from previous SLNB should be used for the incision instead.

The initial step in ALND is creating skin flaps. The flaps should be raised superiorly to the level of the axillary vein and inferiorly to the 4th or 5th rib. Laterally, the flaps should extend to the latissimus dorsi and medially to the pectoralis major. If the ALND is part of a modified radical mastectomy, these flaps may be already raised as part of the mastectomy.

After raising the skin flaps, the surgeon should identify the axillary vein (Fig. 49-2, B). This is typically performed by following the latissimus dorsi muscle to its insertion. Its tendon will course posterior to the lateral aspect of the axillary vein. Once identified, the axillary vein should be skeletonized inferiorly, with its inferior branches ligated. It is important to recognize the thoracodorsal vessels and nerve; these course inferiorly, but will actually enter the axillary vein posteriorly, and should not be ligated.

The axillary vein can be followed medially, leading to the dissection of level II nodes. Currently, there is little indication to remove level III nodes, which therefore are typically not dissected.

After the superior dissection is completed, the specimen can be retracted inferiorly and the remainder of the lymphatic tissue (level I nodes) removed. When the surgeon is beginning to dissect inferiorly, special care should be taken to identify and preserve the long thoracic nerve. This nerve will follow a course along the chest wall and insert into the serratus anterior muscle. Excessive traction on the specimen can raise or tent the long thoracic nerve, which may make the nerve appear to insert into the specimen, subjecting it to ligation.

The thoracodorsal nerve is also important to identify, coursing laterally along the medial surface of the latissimus dorsi muscle (Fig. 49-2, B).

While the surgeon is dissecting inferiorly, an intercostobrachial nerve is seen coursing from the chest wall through the axilla to the upper arm. The intercostobrachial nerve is a sensory nerve to the medial upper arm. Although it can be sacrificed if involved with prominent adenopathy, an attempt should be made to preserve the intercostobrachial nerve.

Inguinal Lymph Node Dissection

Similar to an ALND, dissection of the inguinal lymphatic tissue requires an understanding of the relevant anatomy to avoid neurovascular injury. For an inguinal lymph node dissection (ILND), the borders of the operation are defined by the sartorius muscle laterally, the adductor longus muscle medially, and the inguinal ligament superiorly. The sartorius courses medially across the thigh, creating a triangle containing lymphatic tissue.

The lymphatic tissue of the inguinal region is divided into superficial and deep (Fig. 49-3). The superficial lymph nodes are those in the previously mentioned triangle, superficial to the fascia lata. The lymph tissue surrounds the greater saphenous vein medially and extends laterally and superiorly toward the anterior superior iliac spine (ASIS). These are the primary nodes removed during an ILND.

The deep inguinal nodes are deep to the fascia lata and within the femoral sheath. The nodes course superiorly with the artery and vein beneath the inguinal ligament. Although not routinely excised during ILND, the deep inguinal nodes should be removed as well if there is obvious adenopathy or bulky disease.

Access to this region is obtained through an elongated curvilinear incision (Fig. 49-3, A). Skin flaps are then raised laterally to the sartorius muscle and medially to the adductor longus muscle.

Typically, the surgeon starts the dissection by clearing the lymphatic tissue superior to the inguinal ligament and just medial to the ASIS. The dissection can then be carried inferiorly and laterally along the sartorius muscle (Fig. 49-3, B).

Once the lateral border of the specimen has been dissected, attention is turned to the medial border. While the medial border of the specimen is cleared, the aponeurosis of the external oblique muscle will be identified with the superficial inguinal ring. Also identified is the femoral sheath, containing the femoral artery, vein, and nerve. Care is taken to identify the great saphenous vein, which will uniformly be superficial to the fascia of the medial thigh (Fig. 49-3, C). The great saphenous vein will then drain into the femoral vein through the saphenous opening or fossa ovalis.

This procedure removes the superficial inguinal nodes. If access to the deep nodes is required, an incision can be made through the aponeurosis of the external oblique muscle and inguinal ligament.

If exposed femoral vessels are a concern after the specimen has been removed, a sartorius muscle flap may be used for coverage (Fig. 49-3, D). This maneuver involves dissecting the sartorius from its insertion on the ASIS and rotating it medially over the femoral vessels. This flap is then sutured into place along the inguinal ligament. Care should be taken to ensure that its medial blood supply remains intact.

Summary

Careful attention to neurovascular structures coursing through lymphatic beds will prevent injury during axillary and inguinal lymphadenectomy. For axillary procedures, only tissue inferior to the axillary vein is removed. For inguinal surgery, deep nodes are not routinely resected, and a sartorius flap may be used for exposed vessels.

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