Chronic interstitial nephritis as a cause of tumours of the upper urinary tract. A hypothesis.

Urothelial tumours of the upper urinary tract are rare, but their incidence increases in subjects suffering from phenacetin nephropathy, Balkan nephropathy and infected pyelic calculi. In order to act on the urothelium through the urinary way, a cancerigenic substance must (1) be eliminated with the urine; (2) be absorbed by the urothelium; (3) remain in the tissue for a certain length of time. Any situation leading to a prolongation of intra-tissue stasis favours the action of carcerigenic substances. The hypothesis is put forward that interstitial nephritis, by impeding the reabsorption from the pelvis by pyelo-lymphatic reflux and by making more difficult the lymphatic drainage of the pyelic and ureter walls, leads to a condition favouring carcinogensis, especially if the subject is exposed to contact with even not very active carcinogens. It is possible to foresee that in future the incidence of upper urinary tract tumours should increase in chronic uraemic patients under dialytic treatment and in transplant patients.