Lymphatic Drainage
of Pelvis and Genitalia
The scrotal skin
contains a rich network of lymphatics that join the lymphatics of the penile
skin and the prepuce. These channels, turning outward, terminate in the
superficial inguinal nodes located in the subcutaneous tissue beneath the
superficial fascia, inferior to Poupart ligament and above the great saphenous
vein. Penile and scrotal skin diseases can also progress to the deep inguinal
lymph nodes beneath the fascia lata of the thigh, within the femoral triangle
on the medial side of the femoral canal. Some lymphatics from the penile skin
may also enter the subinguinal nodes that are deep inguinal lymph nodes located
below the junction of the saphenous and femoral veins. Cloquet or Rosenmüller
nodes in this nodal group are located in the external crural canal. Because of
the communication between these nodes, it is important to inspect and remove
all superficial and deep inguinal lymph nodes in penile cancer cases.
The
lymphatics of the glans penis drain toward the frenulum. They then circle the
corona, and the vessels from both sides unite on the dorsum to accompany the
deep dorsal vein beneath Buck fascia. These lymph channels may pass through the
inguinal and femoral canals without traversing nodes until they reach external
iliac nodes that surround the external iliac artery and the anterior surface of
the corresponding vein. Glans penis lymphatics may also terminate in the deep
inguinal lymph nodes and the presymphyseal node located anterior to the
symphysis pubis.
The
lymphatic channels of the penile urethra, passing around the lateral surfaces
of the corpora, accompany those of the glans penis outlined above or may pierce
the rectus muscle to course directly to the external iliac nodes. The bulbous
and membranous urethra drain through channels that accompany the internal
pudendal artery and terminate in the internal iliac or hypogastric (obturator)
nodes that are associated with the branches of the internal iliac (hypogastric)
arteries or in the external iliac nodes.
The rich
lymphatic network of the prostate, as well as the prostatic urethra, ends in
the external iliac lymph nodes. Some lymphatics may accompany the inferior
vesical artery to terminate in the internal iliac or hypogastric (obturator)
nodes. These two nodal groups are most commonly surgically resected when
regional spread of prostate cancer is suspected. Still others may cross the
lateral surface of the rectum to terminate in the presacral and lateral sacral
nodes within the concavity of the sacrum, near the upper sacral foramina and
the middle and lateral sacral arteries. On the basis of this wide variation in
lymphatic drainage of prostate cancer, lymph node dissection is performed for
diagnostic but not therapeutic reasons.
The
lymphatic vessels of the epididymis join those of the vas deferens and
terminate in external iliac nodes. Nodal metastases from testicular tumors in
these nodes
indicate
probable involvement of the epididymis, because the lymphatic drainage of the
testis follows the internal spermatic vein through the inguinal canal to the
retroperitoneal space.
Depending
on the side, testicular lymphatics, after angulating sharply toward the midline
on crossing the ureter, terminate in defined groups of retroperitoneal nodes
located along the vena cava and aorta from the bifurcation to the level of the
renal artery. The
lymphatics
from the right testis drain mainly to the right paracaval nodes, including
precaval, postcaval, lateral caval, and interaortocaval retroperitoneal lymph
nodes. The lymphatics from the left testis drain mainly to the left paraaortic
nodes, including the preaortic, lateral aortic, and postaortic lymph nodes.
Lymphatic collaterals between the two testis sides exist, and contralateral
metastases can occur when the ipsilateral nodes become obstructed.
