The effect of calculi on transitional epithelium. A clinical and cytological study

An analysis has been made of the 9 false-positive cytologic diagnoses in 4000 samples of urine from 1500 patients. They could be traced to 23 patients who had stones in their urinary tract. After removal of the stones the urinary cytology became negative. Thorough clinical examination excluded malignancy. The histological findings in one of these patients offers a possible explanation for the exfoliation of malignant cells and gives support ot the hypothesis that stones can cause reversible changes of the urothelium with the appearance of a malignancy. A casual relationship between stones in the urinary tract and the development of urothelial cancer could not be established.