Diffuse neoplastic change in urothelium from tumour-bearing human lower urinary tract.

In nine patients, who underwent radical cystectomy for transitional cell carcinoma of the bladder, detailed maps were prepared of results of the light microscopic findings and of the surface features of the urothelium as observed by scanning electron microscopy. Scanning electron microscopy revealed a more widespread distribution of residual neoplastic disease than suspected by light microscopy alone. This observation is based on the presence of abnormal cells carrying pleomorphic microvilli in association with other cells infrequently seen in normal healthy urothelium. Such changes have been directly related to neoplastic transformation in numerous experimental studies and have also been observed in human transitional cell carcinoma. This widespread distribution of these markers for neoplastic transformation explains the multiple recurrences of transitional cell carcinoma which characterises neoplastic disease of the bladder.