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.