Inguinal Nodes: Nodules, History, Etymology, Function, Clinical Significance, Lymphatic Drainage and Dissection

Some types of cancer can occur together with lymph node swelling, although it is the least common cause.

Lymph nodes are part of the body’s lymphatic system , which helps maintain fluid balance in the bloodstream, filters waste, and plays an important role in immune defense.

Inguinal lymph nodes are the lymph nodes in the inguinal (groin) region.

There are two layers of inguinal lymph nodes below the inguinal ligament, ranging from the superior anterior iliac spine of the ilium (the most frontal portion of the ilium, the largest pelvic bone) to the pubic tubercle of the pubic bone (a small bony projection), near the bottom, center of the pelvis.

They are the superficial inguinal lymph nodes and the deep inguinal lymph nodes.

Superficial inguinal lymph nodes

Superficial inguinal lymph nodes are the inguinal lymph nodes that form a chain immediately below the inguinal ligament.

The superficial inguinal lymph nodes lie deep in Camper’s fascia, one of the thick layers of connective tissue in the abdominal wall, and drain into the deep inguinal lymph nodes, which cover the femoral vessels on the medial aspect of the thigh.

They are bounded superiorly by the inguinal ligament in the femoral triangle of Scarpa, an area of ​​the upper and inner thigh; laterally by the edge of the sartorius muscle, and medially by the adductor longus muscle and the inguinal ligament.

There are about 10 of these lymph nodes in total that form a chain under the ligament.

They are divided into three groups:

Lower : lower saphenous opening of the leg, receives drainage from the lower legs.

Superolateral : On the side of the saphenous opening, it receives drainage from the lateral buttocks and the lower abdominal wall.

Superomedial : located in the middle of the saphenous opening, receives drainage from the perineum and sexual organs.

There are approximately ten superficial lymph nodes and they drain into the deep inguinal lymph nodes. Inguinal lymph nodes can normally be up to 2 cm in size.

They receive lymphatic afferents from the following:

Integument of the penis, scrotum, perineum, buttock, abdominal wall below the level of the navel again below the level of the iliac crest, vulva, anus (below the pectinate line).

The thigh and medial side of the leg (the lateral leg drains first to the popliteal lymph nodes).

Deep inguinal lymph nodes

There may be about three, four, or five deep inguinal lymph nodes. They are found medially to the femoral vein below the cribriform fascia, the connective tissue of the upper and inner thigh, and on the medial side (closer to the midline of the body) of the femoral vein.

The highest deep inguinal lymph node is in the groin, below the inguinal ligament, and is called Cloquet’s node (also Rosenmuller’s node).

This node is named after the French surgeon Jules Germain Cloquet , or the German anatomist Johann Christian Rosenmüller .

It can also be considered as the lowest of the external iliac lymph nodes. Cloquet’s node is also considered a possible sentinel lymph node.

The deep inguinal lymph nodes drain first to the external iliac lymph nodes of the body, then to the pelvic lymph nodes, and finally to the para-aortic lymph nodes.

Lymph node size

The mean size of an inguinal lymph node, measured on the short axis, is approximately 5.4 mm (range 2.1-13.6 mm), with two standard deviations above the mean of 8.8 mm.

A size of up to 10 mm is generally considered a cut-off value for normal versus abnormal inguinal lymph node size.

History and etymology

The highest or most proximal node is known as the Cloquet node, named after Dr. Jules Germain Cloquet ( 1790-1883), a French surgeon with an interest in hernial disorders , or the German anatomist Dr. Johann Christian Rosenmüller .

This node is located just below the inguinal ligament and can also be considered the node of the lower external iliac chain.

Historically, Cloquet’s nodule has been used as an indicator of pelvic metastasis in melanoma of the lower extremities, although there is evidence that its predictive value is limited.

Inguinal lymph node function

The inguinal lymph nodes of the pelvic organs drain into the pelvic nodal chains bilaterally and into the retroperitoneum. Familiarity with the lymphatic drainage pathways is of great importance for the staging of pelvic tumors.

The most peripheral lymph nodes that drain the pelvis are the inguinal nodes. The inguinal lymph nodes are divided into superficial and deep groups. Superficial inguinal nodules drain the anus, perianal skin, and round ligament of the uterus.

Lymph from the gluteal region and the anterior abdominal wall below the level of the umbilicus also drain to the lateral ganglia in this group. The medial group of superficial lymph nodes receives lymphatics from the perineal genitalia.

The lower group of superficial inguinal lymph nodes receives superficial lymphatics from the lower limb. The deep inguinal lymph nodes are located on the medial side of the femoral vein.

They receive efferents from the deep lymphatic vessels of the lower limb, a small number of efferents from the superficial inguinal nodes, and lymphatic drainage from the glans, penis, or clitoris. The superficial and deep inguinal nodes drain into the external iliac lymph nodes.

The external iliac lymph nodes accompany the external iliac vessels and are divided into medial, posterior, and lateral groups. The medial group of the external iliac lymph nodes drains the urinary bladder, the prostate, the membranous part of the urethra, the cervix, and the upper part of the vagina.

The posterior group receives lymphatics from the internal iliac nodes through the obturator lymph nodes. The lateral group drains the lymph from the superficial and deep inguinal nodes. The external iliac lymph nodes drain to the posterior and lateral common iliac nodes.

The internal iliac nodes accompany the internal iliac vessels and drain lymph from all the pelvic viscera, such as the body of the uterus, the prostate, the upper part of the vagina, the seminal vesicles, the vas deferens, the lower part of the ureter and the bladder.

They also receive lymphatic drainage from the deepest parts of the perineum, the muscles of the buttocks, and the back of the thigh. They send efferents to the external iliac and common iliac chains.

The sacral lymph nodes, which drain directly into the lumbar lymph nodes, and the anatomical obturator lymph nodes, which are sometimes present in the obturator duct, are members of the internal iliac group.

The common iliac lymph nodes accompany the common iliac vessels and are divided into lateral, medial, and posterior groups. The lateral group directly drains the external iliac lymph nodes.

The posterior group receives efferent from the internal and external iliac lymph nodes. The medial common iliac group receives lymph from the internal iliac nodes.

The common iliac ganglia drain into the left and right lateral aortic side chains, which are part of the lumbar ganglia.

Lumbar lymph nodes are divided into right lateral aortic, left lateral aortic, and pre-aortic lymph node groups. The right lateral aortic chain includes paracaval and retrocaval lymph nodes. The pre-aortic chain also includes precaval lymph nodes.

Clinical significance

The presence of swollen inguinal lymph nodes is an important clinical sign because lymphadenopathy (swelling) can indicate an infection (such as orchitis in men) in the lower extremities or spread as a metastasis from cancer, such as anal and vulvar cancer.

The inguinal lymph nodes can normally be up to 2 cm in size. The cut-off value for normal-sized inguinal nodules is up to 10 mm.

Inguinal lymphatic drainage

As a general rule, lymphatic drainage follows the blood supply to the region. However, lymphatic drainage from the perineum differs in this regard because there is a dual pathway.

The deep lymphatics advance upward, following the pudendal vein, draining the deep parts of the urogenital and anal triangles.

However, the superficial lymph vessels of the skin lining the vulvar and anal areas lead to the medial thigh, where they communicate with the superficial inguinal lymph nodes.

Superficial inguinal node adenopathy is well known in many vulvar and anal infections, as well as carcinoma of these regions.

A uterine lymphatic plexus parallels the course of the uterine veins, entering the regional lymph nodes along the internal iliac artery. From these nodes, the lymphatic trunks ascend to the para-aortic nodes in the retroperitoneum.

Afferent lymphatics from the ovary and fallopian tube accompany the ovarian vessels to the para-aortic lymph nodes in the retroperitoneum.

The fundus of the uterus is partially drained by this same route, but it also sends lymphatic vessels anteriorly, parallel to the course of the round ligaments of the uterus. This bilateral course leads lymphatics afferent to the inguinal lymph nodes on both sides of the pelvis.

Inguinal lymph node dissection of the penis

Penile cancer spreads along predictable routes, following the lymphatic drainage of the penis. Initial extension to the superficial inguinal nodes is followed by extension to the deep inguinal nodes of the femoral triangle and finally to the ipsilateral pelvic lymph nodes.

Since inguinal node involvement invariably precedes distant disease spread, the most important prognostic indicator for patients with penile carcinoma remains the presence or absence of regional lymph node metastases.

Metastatic carcinoma of the penis in the regional lymph nodes generally confers a poor prognosis; however, aggressive lymphadenectomy has been associated with better survival and cure in 30% to 60% of patients.

Although the diagnostic value of groin dissection in these patients is clear and the concept of surgical cure has been confirmed in numerous studies, the management of regional lymph nodes in penile cancer remains controversial.

Given the inaccuracy of clinical staging (using physical examinations and imaging studies) and the significant morbidity in groin dissection, many urologists are reluctant to recommend inguinal lymphadenectomy unless the lymph nodes have become palpable.

Because the degree of morbidity is directly related to the extent of the dissection, some surgeons now attempt to limit the limits of dissection while relying on the analysis of frozen sections intraoperatively for evaluation of the margins.

Anatomical considerations

Inguinal lymph node dissection in penile cancer can be prophylactic, therapeutic, or palliative. Prophylactic groin dissection is indicated for patients with an invasive primary tumor (at least TNM stage T1) and no palpable adenopathy.

In this setting, patients undergo a modified superficial inguinal lymph node dissection (including lymph tissue above the fascia lata) between the sartorius muscle laterally and the adductor longus muscle medially.

The saphenous vein is invariably dissected from the nodal bundle and preserved. In the absence of lymph node metastases in the analysis of frozen sections, the procedure is concluded. If metastases are detected, a complete inguinal and ipsilateral pelvic dissection is performed.

Therapeutic groin dissection is indicated for men with palpable open adenopathy after a course of antibiotics to rule out a possible inflammatory component.

In this setting, the saphenous vein has traditionally been divided at the sapheno-femoral junction, the femoral vessels are skeletonized to allow removal of the deep inguinal nodes, and a sartorius muscle flap is generally rotated medially to cover the exposed femoral vessels.

If a mobile lymph node mass is attached to the skin, an ellipse of the involved skin should be excised en bloc with the sample.

Palliative groin dissection is performed to remove all gross residual disease after chemotherapy. To achieve negative surgical margins, resection often includes the inguinal ligament, the spermatic cord, and the ipsilateral testicle.

More rarely, the dissection also includes segments of the femoral artery and vein (with adequate reconstruction using a patch or bypass graft) and lower portions of the rectus abdominis and the external and internal oblique muscles.

Mycocutaneous flaps to cover a large defect may occasionally be required and remain a necessary step to ensure adequate reconstruction.

Complications

Complications systematically reported in the groin dissection series are related to the alteration of the lymphatic vessels that drain the lower extremities and damage to the skin flaps that lie over the devascularization.

These complications include skin border necrosis (45% -62% of dissections), wound infection (14% -17%), seroma formation (6% -16%), and lymphedema (23% -50% ). 71-73 Skin Flap necrosis remains a common complication of groin dissections.

The blood supply to the skin of the inguinal region is derived from the branches of the common femoral artery. Complete groin dissection requires skeletonization of the femoral vessels and ligation of these branches, with possible compromise in blood supply to raised skin flaps.

The viability of the skin margins in this setting depends mainly on the anastomotic vessels that run along the superficial fatty layer of Camper’s fascia.

Because the lymphatic drainage from the penis to the groin is under Camper’s fascia, this layer can be preserved and left attached to the skin above the skin when skin flaps are designed.

Several surgical modifications have been developed to minimize skin flap necrosis:

  • Avoiding the inguinal skin fold during the initial skin incision.
  • Meticulous handling of the skin edge with fine hooks.
  • Creation of thicker skin flaps in which the Camper and Scarpa fascial layers are preserved.
  • Limitation of the extent of flap mobilization (superior to the inguinal ligament and inferior to the tip of the femoral triangle).

Haemostasis and careful excision of the ischemic flap margins at the end of the procedure are mandatory. Additionally, placing horizontal sutures to anchor the underlying muscular aponeurosis can reduce stress on the edges of the fin.

Taken together, these surgical principles have substantially reduced the incidence of skin edge necrosis from 50% to 60% historically reported to 8% in a study reported in 2002. If skin necrosis occurs, debridement and debridement may be necessary. graft split skin.

Lymphedema

Lymphedema after groin dissection can be bothersome and debilitating with respect to ambulation, difficulty standing for long periods, and recurrent episodes of lymphostasis-induced cellulitis.

The overall incidence of postoperative lymphedema has been reported to be ≤50%, and 35% of patients have severe lymphedema.

Limiting the dissection template, specifically sparing the saphenous vein in these circumstances, has resulted in reduced rates of postoperative lymphedema.

This concept was validated in the gynecological literature in a study evaluating the advantages of preservation of the saphenous vein in lymphadenectomy for carcinoma of the vulva.

The study demonstrated a decrease in the incidence of chronic lower extremity edema from 32% to 3% without affecting local cancer control. Persistent lymphedema is rare, but if left untreated it can become progressive, chronic, and incurable.

The International Society of Lymphology developed and advocated a gradual approach to the treatment of chronic lymphedema.

It consists of initial skin care, light manual massage, elevation of the affected limb, range-of-motion exercises, and intermittent compression with low-stretch elastic stockings or multi-layer bandage wrapping.

If no significant improvement is achieved, maintenance therapy should be prompted with a 24-hour compression garment and intermittent pneumatic compression devices.

Diuretics, benzopyrenes (which hydrolyze tissue proteins), and surgical intervention (eg, resection, liposuction, and microsurgical procedures) are all of questionable efficacy.

Comprehensive lymphedema treatment can produce a rapid reduction in all stages of lymphedema, but has the disadvantages of being labor intensive, compliance dependent, and costly.

Wound infection and seroma formation are fairly uniform among contemporary reports, with incidences ranging from 10% to 15%.

Impaired lymphatic drainage and the frequent appearance of seromas make these wounds particularly susceptible to infection.

Parenteral antibiotics with staphylococcal coverage and meticulous preparation of the skin of the genital folds by patients (preoperatively) and the surgical team serve to reduce infectious complications.

Vacuum-assisted closure therapy in complex groin wound failures appears to be superior to conventional wound care without conferring an increased risk of local recurrence.

Local spread for glans tumors

It begins with the invasion of the lamina propria and the corpus spongiosum rich in vasculature. The tunica albuginea acts as a line of defense against invasion of the corpus cavernosum, but with progressive tumor growth this barrier is also compromised.

Fistula formation can lead to secondary involvement of the urethra. Larger tumors can eventually destroy the shaft of the penis and foreskin as well.

Lymph node metastasis is the most common mode of distant spread of the tumor. The superficial inguinal lymph nodes are the first to be involved (sentinel nodes), followed by the deep inguinal group.

Contralateral node metastases can occur because numerous anastomotic lymphatic channels intersect in the midline. In some patients, the pelvic lymph nodes may also be involved.

At initial presentation, 58% of patients have palpable inguinal lymphadenopathy. Nodal metastases are found in 45% of patients with palpable inguinal lymphadenopathy and in 20% of patients with non-palpable lymph nodes.

Secondary infection from cancer of the penis is another cause of inguinal lymphadenopathy; for this reason, sentinel node biopsy is commonly performed.

However, there is controversy regarding the role of prophylactic bilateral inguinal lymphadenectomy. Certain pathologic factors such as stage, grade, and vascular lymphatic invasion can predict the presence of lymph node metastases and help identify patients who may require lymphadenectomy.

Despite the rich vascular channels found in the corpora cavernosa, hematogenous spread is rare. Visceral metastases at initial presentation are seen in less than 2% of patients. Metastases to the liver, lungs, and bones can be seen in untreated cases.