DNA aberrations of bladder mucosa in patients with transitional cell carcinomas.

DNA aberrations in bladder mucosa have been investigated in altogether 26 patients with aneuploid WHO grade 2 and 3 tumours (transitional cell carcinomas; TCC). In about 1/4 of the patients aneuploid cells were found only in the tumour. Hypotetraploid tumours showed the lowest frequency of involvement of the normal appearing mucosa of the trigone (43%). In hypertriploid tumours the corresponding value was 71%. In altogether 14 of the patients, the same type of aneuploid cells was found in the normal appearing mucosa as in the tumour. This indicates frequent involvement of the whole bladder mucosa in the tumour disease. In about 1/4 of the cases other types of ploidy aberrations were found in the normal appearing mucosa than in the tumour. This is indicative of preneoplastic changes in the mucosa, of which only one type of aberrations is associated with tumour growth. In some cases with multiple tumours of the bladder, all the tumours had the same aneuploid stemline, while in other cases the tumours were of different aneuploid stemlines. This is conformal with other reports of atypia in the surrounding mucosa in TCC and with the concept that recurrence of high grade tumours is the consequence of neoplastic involvement of the whole bladder.