Basement membrane and extracellular interstitial matrix components in bladder neoplasia--evidence of angiogenesis

Immunohistochemical studies to localise collagen IV, laminin, fibronectin and tenascin were undertaken in 59 bladder biopsies. These were non-neoplastic or contained foci of flat dysplasia or of transitional cell neoplasia. Collagen IV and laminin were reliably demonstrated in basement membranes but focal loss of reactivity for collagen IV was found in the urothelial basement membrane in some cases of inflammation, dysplasia, and non-invasive papillary transitional cell tumour. Basement membranes were rarely demonstrated around invasive transitional cell carcinomas. Fibronectin and tenascin were found in the sub-urothelial lamina propria and in some urothelial basement membranes. The stroma of invasive tumours reacted strongly for both. Increased numbers of sub-urothelial capillaries were present in association with some cases of cystitis, flat dysplasia or non-invasive transitional cell neoplasia suggesting an angiogenic stimulus in these circumstances. Immunohistochemical staining of basement membrane components is unlikely to be of value in the routine histopathological assessment of transitional cell neoplasms of the bladder.