Aspects of lymphatic vessel configuration of the human male urinary bladder and adjacent organs: A histological basis for understanding the spread of cancer metastases

Abstract

Purpose: The spread of cancer cells via lymphatic vessels (LVs) is supposed to be an early event in the dissemination process of bladder cancer metastasis. However, the configuration of LVs in the human bladder has not been extensively examined microscopically. Therefore the distribution of LVs in the bladder was investigated. Materials and methods: Using D2-40 immunohistochemistry labeling, LVs of bladders and adjacent organs obtained from 10 donated male cadavers, in which the bladders were not dilated post mortem. Results: The bladder smooth muscle layer contained abundant dilated LVs, especially close to the center of the thickness of the bladder body wall. The LVs also made a delicate network in the mucosal tissue, although the density was lower than that in the smooth muscle layer. Independent from the artery and vein, LVs ran along and bundled the smooth muscles. Externally, LVs tended to run in parallel with longitudinal smooth muscles of the outer walls, especially at the posterior surface near the bladder neck. Additional LVs were traced in adjacent organs: prostate, seminal vesicles and rectum. Conclusions: The present study indicates that clinical interventions should be attentive with the treatment of bladder cancer patients, especially considering the bladder neck or trigone area, to prevent the spread of cancer cells via LVs. Keywords: Urinary bladder, Lymphatic vessel, Lymph node, Bladder cancer, Human