Microsurgical Procedures: Minimizing Donor Site Morbidity Following Vascularized Lymph Node Transfer

Key Points

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Superficial inguinal lymph nodes targeted for harvest lie between the groin crease and inguinal ligament.
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The vascular supply of these nodes is typically the superficial circumflex iliac artery.
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These nodes typically drain the lower abdomen; however, there are exceptions and in certain cases may contribute to drainage of the lower limb.
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Reverse lymphatic mapping (RLM) is a technique that allows the surgeon to identify the physiologic drainage pathways of lymph nodes.
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RLM is used to differentiate the lymph nodes that drain the extremity from the lymph nodes that drain the trunk.
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RLM can identify lymph nodes in the groin that contribute significantly to lower limb drainage, allowing the surgeon to avoid these nodes or select an alternative donor site, which may minimize the risk for donor site lymphedema.

Introduction

Vascularized lymph node transfer (VLNT) has steadily been gaining popularity in the treatment of lymphedema as increasing reports of success across multiple centers have surfaced. The concept of a free flap containing vascularized lymph nodes is appealing to many microsurgeons because standard microsurgical techniques seem to be readily applicable to VLNT. However, familiarity with standard free flap harvest and anastomosis are where similarities between a deep inferior epigastric perforator (DIEP) flap and a vascularized groin lymph node flap quickly fade. The potential for donor site lymphedema and permanent additional disability for the patient make VLNT a far more technically challenging and stressful procedure. Relative lack of literature on the specifics of anatomy, lymphatic drainage pathways in the groin, and surgical technique are all barriers to using this technique. However, a significant number of patients have had both objective and subjective improvement across multiple centers following VLNT giving enough credence to this technique that has led to further time and investment in research in this area. Addressing the primary concern of causing donor site lymphedema, the authors have described the technique of reverse lymphatic mapping (RLM) in VLNT to identify which nodes are draining the limb and which nodes are draining the trunk, in order to precisely harvest lymph nodes with the least risk of causing lymphedema at the donor site. An anatomic study of this region using magnetic resonance angiography (MRA) and mapping of nearly 2000 lymph nodes previously published by the authors has clarified the anatomy of this region and has contributed to the evolution of the technique we present in this chapter. Future long-term prospective studies will further refine the indications and allow us to better understand the risk/benefit equation for VLNT. The purpose of this chapter is to describe our surgical technique for vascularized groin lymph node transfer utilizing RLM.

Concepts

Regional Anatomy

The vascular pedicle for the vascularized groin lymph node flap is commonly based on the superficial circumflex iliac artery (SCIA). This artery originates from the common femoral artery where it makes a short hairpin turn superiorly and laterally as it nearly parallels the course of the inguinal ligament. The flap is drained from both venae commitantes as well as the superficial circumflex iliac vein (SCIV), and to some degree, the superficial inferior epigastric vein (SIEV). The SCIV and SIEV join and continue to inferiorly diverge from the SCIA, and empty into the saphenous bulb near the junction of the greater saphenous vein and the femoral vein.

The lymph nodes supplied by the SCIA are concentrated at the junction of the SCIV and SIEV based on a published anatomic study by the authors. This correlates to a region one-third the distance from the pubic tubercle to the anterior superior iliac spine (ASIS) and 3 cm perpendicularly below this point. These lymph nodes are almost always located above the groin crease but below the inguinal ligament—never below the groin crease. Lymph nodes located below the groin crease typically contribute significantly to drainage of the lower limb, and the sentinel lymph nodes draining the lower limb are commonly along the femoral vessels just below or at the groin crease. Lymph nodes medial to the SIEV may also contribute to lower extremity drainage and may need to be avoided as well. These are solely static anatomic guidelines, not rules, and the physiologic drainage in each individual patient can vary and should be assessed by RLM. In some cases, there are lymph nodes above the groin crease that contribute significantly to lower extremity drainage.

There are also sensory nerves in the operative field: direct branches from the femoral nerve and the lateral femoral cutaneous nerve. Femoral nerve branches may entangle the pedicle and sacrifice may lead to numbness in the anterior thigh. The lateral femoral cutaneous nerve runs medial to the anterior superior iliac spine and deep to the abdominal wall fascia at this level and is typically not seen during flap harvest.

Flap Design

Anatomic landmarks are marked first: a line is drawn from the pubic tubercle and ASIS corresponding to the inguinal ligament. The natural groin crease is marked, the femoral artery is palpated and marked, and the sartorius muscle border is marked. The femoral triangle becomes easily apparent and is the origin of the pedicle. We typically utilize the groin flap as a buried flap without a skin paddle for transfer to the axilla in upper extremity lymphedema. In this case, the incision is planned over the course of the SCIA, which can be localized with a handheld Doppler and/or by using anatomic landmarks: the SCIA courses obliquely approximately 3 cm below the inguinal ligament, but always above the groin crease ( Figure 19.1 ). Incision length depends on the amount of soft tissue desired. If there is a large axillary dead space following extensive scar excision, the incision can be extended laterally to create an appropriately larger flap. The flap width is limited inferiorly by the groin crease but can be extended superiorly as needed. A typical flap dimension is 5 × 10 or 5 × 12 cm. If a distal transfer is planned to the forearm or wrist, the skin paddle is oriented so that the course of the SCIA is centered within it.

Patient Selection

Patients who have a history of lower extremity lymphedema, a history of pelvic radiation or oncologic surgery, or any predisposing factor for developing lower limb lymphedema may not be a candidate for a vascularized groin lymph node transfer. In our practice, patients with a body mass index of greater than 32 are generally not operated on until body weight is optimized. Patients who have severe venous insufficiency that cannot be treated may also not be good candidates for lymph node transfer. A reflux Duplex ultrasound can assess for venous insufficiency if there is any question. Elevated venous pressures may compromise the hypothesis of the lympho-venous shunting that occurs at the level of the lymph node. An ideal patient would be someone who is thin, healthy, and compliant, with significant pitting edema. This confirms there is a large fluid component (as opposed to hypertrophic fat) in their affected limb, which may respond more to a lymph node transfer.

Preoperative Considerations

As most of our patients are cancer survivors, sooner or later we are likely to encounter a patient who presents with a recurrence, which will need to be ruled out. Physical exam includes palpation of all lymph node basins and a breast exam for breast cancer survivors. A breast or axillary mass, or rapidly progressive lymphedema are presumed to be a recurrence until proven otherwise. Clearance from the patient’s oncologist or treating physician and discussion with the therapist and other key players in the patient’s care provides a more complete perspective, which is important when going ahead with this procedure.

Prior to embarking on lymph node transfer, all patients are first referred to a certified lymphedema therapist for evaluation and treatment. There are a significant number of patients who find adequate benefit from therapy alone and are satisfied without desiring a surgical option. If the patient is already in treatment, the procedure and post-operative regimen are discussed and planned with the therapist.

Informed Consent

A realistic set of expectations should be clearly discussed with the patient; VLNT is typically not a cure for lymphedema but offers the potential for improvement. The most dreaded potential complication following lymph node transfer is the potential for donor site lymphedema, which is discussed at length with the patient. This is the reason RLM is performed, that guides us in avoiding lymph nodes that drain the lower limb. During the course of the procedure, RLM may also reveal that there are lower extremity sentinel nodes in the flap itself before it is fully dissected and allows the surgeon an option to abandon the donor site to avoid risk to the patient. While it is not common, there were two cases in the past four years where the use of RLM in the groin impacted our surgical plan including switching to an alternate donor site. For this reason, we consent the patient for the possibility of using an alternative donor site if this situation were to arise.

Pros and Cons of the Inguinal Donor Site

The most common indication for a vascularized groin lymph node flap is for breast cancer-related lymphedema. The benefits of this flap are the hidden donor site scar and the familiarity of the anatomy to microsurgeons who have performed groin flaps. The drawbacks are a short pedicle, typically less than 2 cm, and a vessel caliber between 1–1.5 mm, making its use limited in severe cases where the recipient site requires a longer pedicle. The potential complications of harvesting this flap include: potential risk for donor site lymphedema, potential loss of sensation in the anterior thigh, and seroma, which is the most common complication in our series.

Preoperative Workup

The preoperative workup also includes modalities to evaluate outcome, ideally both objective and subjective. We perform preoperative imaging on all patients including MRA to study both donor and recipient anatomy, to evaluate the fluid content in the affected limb, and obtain volumetric measurements. Lymphoscintigraphy and indocyanine green lymphangiography are also performed to obtain a baseline to compare with postoperative imaging. In patients with an axillary dissection, preoperative MRA has revealed a number of significant findings including, axillary vein narrowing or occlusion, and ligation of the thoracodorsal vessels; it has also allowed us to choose the groin donor site with the most lymph nodes and most favorable anatomic layout ( Figure 19.2 ). This is valuable information that can affect the operative plan and reduce uncertainty during the procedure.