Lymphatic drainage of the prostate gland in canines.

Lymphography of the penis was performed in 3 canines, and direct intraprostatic injection of India ink was carried out in 8 canines to visualize lymphatic drainage of the prostate gland. In penile lymphography, the contrast medium drained in 2 directions: (1) lymphatic drainage into the external and common iliac lymph nodes through the superficial inguinal lymph nodes; (2) lymphatic drainage into the presacral lymph nodes along the urethra and posterior wall of the pelvis. Lymphatics of the prostate gland drained in 3 directions: (1) lymphatics from the prostate gland mainly drained along the prostatic and internal iliac vessels into the internal and common iliac lymph nodes, (2) lymphatics from the dorsal region near the urinary bladder drained along the ureter into the common iliac lymph nodes, and (3) lymphatics from the apex of the prostate gland drained along the posterior wall of the pelvis into the presacral lymph nodes. Prostate cancer developed at the apex is estimated to preferentially metastasize to the presacral lymph nodes, and drug injection into the penile lymphatics is considered to be a good route to treat metastases of lymph nodes in the pelvis.