Urine cytology as a useful screening method for polyoma virus nephropathy in renal transplant patients: a single-center experience.

Polyoma virus nephropathy occurs in 3% to 4% of renal transplant recipients, causing graft loss in 50% of cases. In this study we sought to identify the incidence of polyoma virus infection among our transplanted patients on the basis of age, sex, creatinine level, and postoperative period. During this study the 1086 urine samples collected from 362 patients were centrifuged and stained with the Papaniclaou method. All slides were classified as negative or positive (>1 decoy cell/sample). Among 1086 urine cytologies from 241 men and 121 women, decoy cells were identified in 26.6% (96) of patients, including 29.9% (n = 72) men and 20% (n = 24) women. The incidence of decoy cells (26.6%) was increased among men and associated with a longer transplantation period (P < .05). A significant relation was detected between older age and positive urine cytology. The patients with positive urine cytology for decoy cells showed a greater incidence of abnormal plasma creatinine values (26%) compared with patients showing a negative urine cytology (13.5%). In conclusion, identification of cells with viral inclusions (decoy cells) may help with the diagnosis of viral replication or active infection, therefore, routine urine cytology may be used as screening method for the detection of polyoma virus infection.