The femoral triangle is defined by the sartorius muscle laterally and the adductor longus muscle medially. These two muscles meet at the apex of the femoral triangle inferiorly. The inguinal ligament defines the superior extent of the femoral triangle. In the operation of open inguinal lymphadenectomy, the fatty and lymphatic contents of the femoral triangle are cleared, commencing superiorly on the lower abdominal musculature 5–7 cm above the inguinal ligament and extending inferiorly to the apex of the femoral triangle. The major vascular structures in the femoral triangle are all preserved during the operation, including the common femoral artery (CFA), superficial femoral artery (SFA), and profunda femoral artery (PFA) and the common femoral vein (CFV), superficial femoral vein (SFV), and profunda femoris vein (PFV). However, the long saphenous vein (LSV) is removed as part of the operative specimen after ligation at the saphenofemoral junction (SFJ) and again at the inferior extent of the dissection.
Further structures that act as landmarks in the dissection include:
- 1.
The lateral cutaneous nerve of the thigh as it emerges from under the inguinal ligament laterally and courses obliquely across the upper sartorius muscle
- 2.
The superficial external pudendal artery, which is usually located just inferior to the saphenofemoral venous junction (not in the above figure)
- 3.
The cutaneous branches of the superficial branch of the femoral nerve as they course inferolaterally across the sartorius muscle further down the thigh and the saphenous nerve that courses toward the saphenous vein in the lower medial thigh
- 4.
The femoral canal with its contents including the lymph node of Cloquet medial to the femoral vein as it passes behind the inguinal ligament to become the external iliac vein
Indications
The most common indication for open inguinal lymphadenectomy is for the regional control of malignant solid tumors when metastatic spread to groin lymph nodes has occurred. In Australia, metastatic melanoma is the most common indication, followed by metastatic squamous cell carcinoma. Less common indications include metastatic Merkel cell carcinoma, metastatic sarcoma, and metastasis from rare skin adnexal tumors. The relative frequency of primary tumor pathologies differs in countries that have a lower incidence of melanoma and other sun exposure-related skin cancers.
In the past, the usual method of detection of metastatic melanoma in inguinal lymph nodes was by clinical or radiological assessment, with confirmation by fine-needle cytology or core biopsy. Some centers performed elective lymph node dissection for intermediate- and high-risk melanoma patients, although the great majority of patients did not have metastatic nodal disease when the operative specimens were examined. Nowadays the diagnosis is most commonly made after detection of micrometastatic disease by sentinel lymph node biopsy (SLNB).
Extent of Lymphadenectomy
In cases with apparently isolated malignancy in the inguinofemoral region, there is ongoing controversy as to whether the appropriate extent of surgery is inguinal lymphadenectomy alone or ilioinguinal lymphadenectomy, with clearance of iliac and obturator lymph nodes. It is unclear whether there are significant advantages to adding a pelvic dissection to the superficial inguinal lymphadenectomy or for that matter whether adding pelvic dissection adds any significant morbidity [1–3]. In an international survey, when 191 melanoma surgeons were asked what operation they would do for a positive inguinal SLNB, the replies were almost evenly split: 1/3 inguinal dissection, 1/3 ilioinguinal dissection, and 1/3 operation dependent on the specific circumstances [4]. For melanoma patients, there is currently a randomized controlled trial pilot study evaluating the question of extent of surgery [5].
Preoperative Staging
From the cancer perspective, it is common to perform full preoperative metastatic staging with whole-body PET/CT or CT chest, abdomen, and pelvis as well as CT or MRI of the brain.There are circumstances where inguinal lymphadenectomy may still be recommended even when low-volume distant metastatic disease is identified. These include situations where the multidisciplinary team is worried about the likelihood of disease progressing in the inguinal area, with loss of regional control. In melanoma patients with low-volume distant metastatic disease, this is less likely now, with the availability of effective systemic therapies, which are often used first, and inguinal or ilioinguinal lymphadenectomy reserved for regional salvage if it is necessary.
Consideration may also be given to suitability for enrollment in any neoadjuvant or adjuvant therapy trials that are open at the institution.
Preoperative Assessment
General anesthesia is required. The preoperative workup is tailored to be appropriate for the patient’s preexisting medical comorbidities. Open inguinal lymphadenectomy is not deep body cavity surgery, and there is a very low risk of major bleeding. Postoperative pain is usually not at a high level. The major early complications are poor wound healing and the development of a seroma. As far as feasible, it is desirable to mitigate risks by stopping smoking and optimizing the management of diabetes and any other systemic disease.
Surgical Technique
Positioning
The patient is positioned supine on the operating table. Most surgeons externally rotate the hip and flex the knee, placing the foot at the level of the opposite mid-calf area to improve access to the groin. However, this is not essential and the operation can also be done without this maneuver. Preoperatively surface marking with an operative marking pen of the location of the known disease and extent of dissection as well as the planned incision is logical.
Incisions
There are several suitable surgical incisions . These include single long incisions (straight or curvilinear or sigmoid), but it is useful to remove an ellipse of skin to reduce the risk of skin edge necrosis and reduce the laxity of the tissues after closure (Fig. 12.1, Panel a). Separate minimal access incisions sited above and below the inguinal ligament may also be used [6].
Fig. 12.1
Operative photos for open inguinal lymphadenectomy. Panel (a): skin markings for incision . Inguinal ligament and site of known metastatic lymph node marked. Panel (b): fatty tissue mobilized off lower abdominal wall to level of inguinal ligament. Care should be taken here when dissecting onto the femoral vessels. Panel (c): dissection defined laterally along the line of the sartorius muscle. The tributaries of the long saphenous vein and cutaneous branches of the femoral nerve are shown crossing the muscle. Panel (d): once the lateral extent of dissection is defined (see Panel c), the en bloc dissection starts at the level of the inguinal ligament dissecting in the fascial plane from the medial edge of the sartorius muscle across the common femoral artery avoiding the femoral nerve in the deeper plane. Panel (e): dissection exposes the common and superficial femoral arteries and then starts to expose the common femoral vein. The cutaneous branches of the femoral nerve that are not near the tumor can be preserved and are seen crossing the sartorius muscle inferolaterally. Panel (f): a vessel loop sling is around the saphenofemoral junction. The tissue up to the neck of the femoral canal is dissected in front of the pectineus muscle, but the femoral canal was ablated by earlier hernia surgery. Panel (g): the dissection proceeds caudally along the front of the superficial femoral artery. The fascia over the adductor longus muscle medially can be removed to give a clean plane of dissection. Panel (h): the caudal extent of the dissection is the apex of the femoral triangle where the long saphenous vein is divided again. Panel (i): because the single long ellipse incision leaves the femoral vessels exposed in the base of the dissection, the sartorius muscle is reflected after dividing its origin from the anterior superior iliac spine. The segmental neurovascular supply can be seen entering the muscle. It will be sutured to the inguinal ligament to cover the vessels
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