Presentation Authors: Nobuyuki Hinata*, Yukari Bando, Masato Fujisawa, Kobe, Japan
Introduction: The spread of cancer cells via lymphatic vessels (LVs) is supposed to be an early event in the dissemination process of bladder cancer. However, the configuration of LVs in the human bladder has not been extensively examined. Then we sought to investigate the distribution of LVs in the human urinary bladder.
Methods: We examined distribution and density of the LVs in the urinary bladder obtained from 12 donated human male cadavers by using D2-40 immunohistochemistry. More than 10 tissue blocks were prepared from each cadaver, each block including 1) base of the bladder; 2) neck of the bladder; 3) trigone of the bladder; 4) prostate and urethra; 5) seminal vesicle; and 6) rectal wall. Twenty sections were cut from each block, then densities and diameters of the lymphatic vessel were calculated for each block.
Results: The bladder smooth muscle layer contained abundant dilated LVs, especially in the inner layer of the smooth muscle of the bladder. The LVs also made a delicate network in the mucosal tissue, although the density was lower than that in the smooth muscle layer. Externally, LVs tended to run in parallel with longitudinal smooth muscles of the outer walls, especially at the posterior surface near the bladder neck and trigone. Lymphatic vessel density was significantly higher at the neck and trigone than at the base of the bladder.
Conclusions: Dense distribution of the lymphatic vessels at the neck and the trigone of the urinary bladder showed extravesical course in parallel with longitudinal smooth muscles. The findings obtained in the present study may explain the anatomical basis that tumors located at the neck and the trigone of the bladder could have different patterns of nodal metastases than at the dome of the bladder.