Urine cytology findings in analgesic nephropathy.

Urine cytology screening for neoplasm led to the detection of 3 urothelial carcinomas and 1 severe urothelial dysplasia in 98 patients with analgesic-induced papillary necrosis. A further 18 patients had changes suggesting that they were at risk of incurring malignancy in the near future. Routine urine cytology is recommended in all cases of analgesic nephropathy.