Detection of neoplastic and preneoplastic urothelia by combined scanning and transmission electron microscopy of urinary surface of human and rat bladders.

Scanning and transmission electron microscopy reveal distinct differences between the appearance of the luminal surface membrane of normal urothelium and those of transitional cell tumours of both human and rat bladder. The luminal surface membrane of the preneoplastic rat urothelium shows features similar to those seen in the fully developed tumour. In human tumour-bearing bladders the urothelium away from the transitional cell tumour is not recognizable as being preneoplastic by light microscopy. However, by scanning or transmission electron microscopy, the luminal membrane in some areas shows changes identical to those in the preneoplastic rat bladder. These observations are in accordance with the clinical behaviour of the urothelium in patients with vesical transitional cell tumours which tend to recur in disparate site. We suggest that scanning electron microscopy of the bladder urothelium away from the tumour may be of prognostic value for indicating the subsequent biological behaviour of the urothelium.