Acquired cystic transformation of the kidneys of haemodialysed patients.

In the present study, the kidneys of patients who had been on maintenance haemodialysis for variable periods of time were examined at autopsy. In 21 of the 22 patients, multiple pinhead-size to pea-size, non-loculated cysts were observed both in the cortex and the medulla. In some of the cysts (4/20 patients), papillary adenomata were observed which were visible by light microscopy in 3 cases and macroscopically in 1 case. Clinical complications resulting from haemorrhage or neoplastic transformation were not observed in any of the patients of this series. Similar cysts, smaller in size and fewer in number, were also observed in kidneys of uraemic patients who had not been dialysed. Thus, the lesion does not appear to be a specific consequence of maintenance haemodialysis. It appears more likely that extensive cystic transformation of the kidneys of patients in terminal renal failure is made possible by prolonged survival on maintenance haemodialysis. The possibility of malignant transformation of the papillomata cannot be refuted, but epidemiological surveys fail to document more frequent occurrence of renal carcinoma in dialysed patients.