Fine-structural evidence for vascular injury in patients with interstitial cystitis.

Bladder vessel walls of 20 patients with interstitial cystitis were studied by the electron microscope. 14 (70%) had severe endothelial injury. 10 (50%) showed injured smooth muscle cells. Odd basement membrane proliferations and disruptions were seen. Clusters of microfibrils about 10 nm in diameter and numerous partially membrane-bound vesicles of 100-600 nm with granular or tiny vesicular content ("granulovesicular bodies") were also seen. Intercellular junctions of endothelial cells were open and there was emigration of polymorphonuclear leucocytes and platelets. The findings show pronounced vascular injury to have taken place, with neoformation of elastic tissue. It is suggested that the injury is immunologically mediated and that particularly those clusters of connective tissue microfibrils not yet covered by an amorphous elastin component may be involved in the pathogenesis of this disease.