Role of Urinary Cytology in Detecting Human Polyoma BK Virus in Kidney Transplant Recipients

OBJECTIVE: To report data on the evaluation of the efficacy of urine cytology in detecting BK virus (BKV). MATERIAL AND METHODS: Papanicolaou-stained cytospin preparations of randomly collected urine samples from 8 renal transplant (RTR) patients (5 males, 3 females, age: 23-63 years) who previously tested positive for BKV by PCR in urine or blood or both were studied. Urine sediment from 3 of the patients was processed for ultrastructural examination (EM). Renal biopsies before and after BKV detection were also evaluated. RESULTS: The interval between renal transplant and urine cytology ranged between 2 and 5 years. Urine from females was difficult to assess due to vaginal contamination. In 2 of the 5 urine specimens from male recipients BKV-infected decoy cells were identified. Viral particles suggestive of BKV were identified on EM in 2 of the 3 specimens studied. Kidney biopsies showed morphologic features suggestive of BKV infection in 2 cases, 1 each detected on cytology and EM, respectively. CONCLUSION: Screening for the presence of decoy cells in urine provides a simple sensitive means for the diagnosis of BKV nephropathy in RTR.