The effect of intravesical instillations of thiotepa, mitomycin C, and adriamycin on normal urothelium: an experimental study in rats.

The effects of intravesical instillations of thiotepa, mitomycin C and adriamycin on the normal urothelium were studied in rats. Changes in the bladder wall in the form of fibroblastic atypia and submucous fibrous plaques were significant in the mitomycin C treated group. In 46% of mitomycin C treated animals there was urothelial atypia and in one animal, the atypia was severe enough to resemble carcinoma in situ. None of the rats treated with thiotepa showed intramural fibrous plaques or fibroblastic atypia and only 8% showed urothelial atypia. In the group treated by adriamycin instillation, 17% showed intramural fibrous plaques, but none showed urothelial atypia or fibroblastic atypia. The fibroblastic atypia and submucosal fibrous plaques seen in the mitomycin treated group may explain the reduced bladder capacity seen in the clinical setting.