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Urine Cytology as a Useful Screening Method for Polyoma Virus Nephropathy in Renal Transplant Patients: A Single-Center Experience
Infection
Urine Cytology as a Useful Screening Method for Polyoma Virus Nephropathy in Renal Transplant Patients: A Single-Center Experience B. Geramizadeh, J. Roozbeh, S.-A. Malek-Hosseini, N. Azarpira, M. Ayatollahi, H. Salahi, M. Aghdaee, and R. Yaghoobi ABSTRACT 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.
H
UMAN POLYOMA VIRUSES are members of the Papova virus family.1 They have a double-stranded DNA genome. The best known species in this genus are the BK, the JC, and the Simian viruses.2 The documented worldwide rate of seroprevalance among adults is 60% to 80%.3 Primary infection occurs in childhood with a “flulike” course; urinary excretion of BK virus is observed in 4% to 6% of immunocompetent patients. The virus remains latent in the urogenital tract. Spontaneous activation is rare without immunosuppression,4 but often occurs in these
patients in asymptomatic fashion.4 In addition BK virus has been implicated in autoimmune diseases and possibly cancer.1,5 The virus is now recognized as a cause of severe renal From the Transplant Research Center, Pathology Department, Shiraz University Medical Sciences, Shiraz, Iran. Address reprint requests to Bita Geramizadeh, Transplant Research Center, Pathology Department, Shiraz University Medical Sciences, PO Box 71345-1864, Shiraz, Iran. E-mail: [email protected]
© 2006 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/06/$–see front matter doi:10.1016/j.transproceed.2006.08.177
Transplantation Proceedings, 38, 2923–2925 (2006)
2923
2924
GERAMIZADEH, ROOZBEH, MALEK-HOSSEINI ET AL
allograft dysfunction and potential graft loss. It is estimated that 10% to 60% of immunosuppressed renal transplant patients display reactivation of polyoma virus. This is accompanied by shedding of urothelial cells. BK virus shedding can be detected in the urine of these patients by the presence of cells containing viral inclusion bodies known as “decoy cells.”4 Our aim was to evaluate the incidence of polyoma virus infection among renal transplant recipients based upon the presence of decoy cells in centrifuged urine samples. MATERIALS AND METHODS The target population for the present study was 362 kidney transplant recipients from whom 1086 urine samples were obtained; three per patient. Urine samples were obtained as the clean catch midstream method, mostly the early morning fresh sample, namely, the patient’s first voided morning urine being discarded and the second fresh sample submitted to the lab. After urine samples had been cytocentrifuged for 5 minutes, the slides were stained with the Papaniclaou method and examined by a pathologist to detect decoy cells— cells with viral inclusions. All positive slides were confirmed at least by one other pathologist in the department. If one of three urine samples obtained from a patient was positive for the presence of decoy cells, this patient was included in the positive group for Decoy cells were characterized by increased nuclear volume, basophilic nucleus, condensed chromatin, and a perinuclear halo. Urine samples with more than one (⬎1) decoy cell were considered to be positive. Statistical analysis was performed using the chi-squire and Student’s t test. To evaluate kidney function, plasma creatinine values at the time of urine cytology were considered abnormal when it was above 1.25 mg/dL for men and 1.1 mg/dL for women.
RESULTS
Among 362 renal transplant recipients were 241 men and 121 women. Decoy cells were observed in 96 patients (26.6%): 72 men (29.9%) and 24 women (20%). Among 41 patients less than 1 month from transplantation 5 (12.2%) had a positive urine cytology for decoy cells. Among 54 patients between 1 and 3 months posttransplantation period 10 (18.5%) had positive cytology. Among 13 patients between 3 and 6 months posttransplantation, 3 (15.4%) showed positive samples. Among 253 patients more than 6 months posttransplantation, 78 (31.2%) urine samples were positive for decoy cells (Table 1). The mean age of the patients was 34 ⫾ 11.69 years (range ⫽ 6 to 67). Urine cytology was most frequently positive in patients 40 to 49 years old (30.2%) and least often, for patients below 20 years (17.6%). Among Table 1. Decoy Cell Prevalence in Urine Cytology After Varying Posttransplant Period Urine Cytology Posttransplantation Period
Positive
Negative
Total No. of Patients
⬍1 month 1–3 months 3–6 months ⬎6 months
12.2% (5) 18.5% (10) 15.5% (2) 31.1% (79)
87.8% (36) 81.5% (44) 84.6% (11) 68.9% (175)
41 54 13 254
Table 2. Plasma Creatinine (P-Cr) Levels (Normal or Abnormal) in Patients With Urine Cytology Positive or Negative for Decoy Cells Urine Cytology
Abnormal P-Cr
Normal P-Cr
Total No. of Patients
Positive Negative
25 (26.0%) 36 (13.5%)
71 (74.0%) 230 (86.5%)
96 266
362, 61 (16%) subjects displayed elevated plasma creatinine levels. The (96) patients with urine cytology positive for decoy cells included 25 (26.0%) with elevated creatinine levels, while 36 (13.5%) of the (266) patients with negative urine cytology examinations showed elevated plasma creatinine levels (P ⬍ .05; Table 2). DISCUSSION
The (26.6%) incidence of decoy cells among kidney transplant recipients was concordant with previous reports showing in 20% to 40% rates.6 Similarly, an increased prevalence of decoy cells was observed in men (29.9%) as compared to women (20%), as previously shown.1 In this study we observed a significant relation between increasing age and an higher incidence of decoy cells; there was a significantly higher incidence of decoy cells among patients above versus below 20 years old. Previous investigations had demonstrated increased incidence in the higher age groups, possibly because they become more immunocompromised with the same doses of immunosuppressive medications compared with younger patients, therefore rendering them at increased risk for polyoma virus infection.1 Previous studies demonstrated that the prevalence of polyoma virus infection increases in patients after a prolonged posttransplantation period (median of 9 months),7 a finding confirmed in our study among patients more than 6 months posttransplantation whose prevalence of decoy cells (31.2%) was significantly greater than those with shorter posttransplantation periods (P ⬍ .05). Regarding kidney function in transplanted patients, a relationship between an elevated plasma creatinine value and decoy cells was detected: an abnormal plasma creatinine was detected in 26% of patients having positive urine cytology for decoy cells as compared to those (13.5%) negative for decoy cells on urine cytology. These abnormal plasma creatinine levels were similar to previous studies that showed that patients with BK virus nephropathy showed high serum creatinines that mimicked either tubular necrosis or rejection.1 Despite a low positive predictive value of decoy cells in urine, its absence has a negative predictive value of 100%. As urine cytology is easy to perform with low cost, it is a useful tool to investigate active polyoma virus infection. Considering the risk of graft loss due to polyoma virus infection, it is suggested that routine urine cytology should be used as a screening method for the detection of polyoma virus infection. While negative cytology excludes the presence of polyoma virus nephropathy, the presence of decoy cells in urine cytology can suggest the
URINE CYTOLOGY TO SCREEN FOR PVN
diagnosis of the active viral infection although it is not a definite indication of polyoma virus nephropathy. Decoy cells in the presence of high creatinine represent a good clue for further investigation. REFERENCES 1. Hirsch HH, Steiger J: Polyoma virus BK. Lancet 3:611, 2003 2. Pahari A, Rees L: BK-virus associated renal problems and clinical manifestations. Pediatr Nephrol 18:743, 2003
2925 3. Nickeleit V, Hirsch HH, Binet IF: Polyoma virus infection of renal allograft recipients. J Am Soc Nephrol 10:1080, 1999 4. Nephropathy due to polyoma virus BK. N Engl J Med 18: 342:1361, 2000 (Editorial) 5. Pietropaolo V, Tarato CD: Tran placental transmission of human polyoma virus BK. J Med Virol 56:372, 1998 6. Santos RLS, Manfrinatto JA: Urine cytology as a screening method for polyoma virus active infection. Transplant Proc 36:899, 2004 7. Hliu L, Fresco R, Picken MM: Intranuclear inclusions in allograft kidney. Arch Pathol Lab Med 125:973, 2001
Urine Cytology as a Useful Screening Method for Polyoma Virus Nephropathy in Renal Transplant Patients: A Single-Center Experience B. Geramizadeh, J. Roozbeh, S.-A. Malek-Hosseini, N. Azarpira, M. Ayatollahi, H. Salahi, M. Aghdaee, and R. Yaghoobi ABSTRACT 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.
H
UMAN POLYOMA VIRUSES are members of the Papova virus family.1 They have a double-stranded DNA genome. The best known species in this genus are the BK, the JC, and the Simian viruses.2 The documented worldwide rate of seroprevalance among adults is 60% to 80%.3 Primary infection occurs in childhood with a “flulike” course; urinary excretion of BK virus is observed in 4% to 6% of immunocompetent patients. The virus remains latent in the urogenital tract. Spontaneous activation is rare without immunosuppression,4 but often occurs in these
patients in asymptomatic fashion.4 In addition BK virus has been implicated in autoimmune diseases and possibly cancer.1,5 The virus is now recognized as a cause of severe renal From the Transplant Research Center, Pathology Department, Shiraz University Medical Sciences, Shiraz, Iran. Address reprint requests to Bita Geramizadeh, Transplant Research Center, Pathology Department, Shiraz University Medical Sciences, PO Box 71345-1864, Shiraz, Iran. E-mail: [email protected]
© 2006 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710
0041-1345/06/$–see front matter doi:10.1016/j.transproceed.2006.08.177
Transplantation Proceedings, 38, 2923–2925 (2006)
2923
2924
GERAMIZADEH, ROOZBEH, MALEK-HOSSEINI ET AL
allograft dysfunction and potential graft loss. It is estimated that 10% to 60% of immunosuppressed renal transplant patients display reactivation of polyoma virus. This is accompanied by shedding of urothelial cells. BK virus shedding can be detected in the urine of these patients by the presence of cells containing viral inclusion bodies known as “decoy cells.”4 Our aim was to evaluate the incidence of polyoma virus infection among renal transplant recipients based upon the presence of decoy cells in centrifuged urine samples. MATERIALS AND METHODS The target population for the present study was 362 kidney transplant recipients from whom 1086 urine samples were obtained; three per patient. Urine samples were obtained as the clean catch midstream method, mostly the early morning fresh sample, namely, the patient’s first voided morning urine being discarded and the second fresh sample submitted to the lab. After urine samples had been cytocentrifuged for 5 minutes, the slides were stained with the Papaniclaou method and examined by a pathologist to detect decoy cells— cells with viral inclusions. All positive slides were confirmed at least by one other pathologist in the department. If one of three urine samples obtained from a patient was positive for the presence of decoy cells, this patient was included in the positive group for Decoy cells were characterized by increased nuclear volume, basophilic nucleus, condensed chromatin, and a perinuclear halo. Urine samples with more than one (⬎1) decoy cell were considered to be positive. Statistical analysis was performed using the chi-squire and Student’s t test. To evaluate kidney function, plasma creatinine values at the time of urine cytology were considered abnormal when it was above 1.25 mg/dL for men and 1.1 mg/dL for women.
RESULTS
Among 362 renal transplant recipients were 241 men and 121 women. Decoy cells were observed in 96 patients (26.6%): 72 men (29.9%) and 24 women (20%). Among 41 patients less than 1 month from transplantation 5 (12.2%) had a positive urine cytology for decoy cells. Among 54 patients between 1 and 3 months posttransplantation period 10 (18.5%) had positive cytology. Among 13 patients between 3 and 6 months posttransplantation, 3 (15.4%) showed positive samples. Among 253 patients more than 6 months posttransplantation, 78 (31.2%) urine samples were positive for decoy cells (Table 1). The mean age of the patients was 34 ⫾ 11.69 years (range ⫽ 6 to 67). Urine cytology was most frequently positive in patients 40 to 49 years old (30.2%) and least often, for patients below 20 years (17.6%). Among Table 1. Decoy Cell Prevalence in Urine Cytology After Varying Posttransplant Period Urine Cytology Posttransplantation Period
Positive
Negative
Total No. of Patients
⬍1 month 1–3 months 3–6 months ⬎6 months
12.2% (5) 18.5% (10) 15.5% (2) 31.1% (79)
87.8% (36) 81.5% (44) 84.6% (11) 68.9% (175)
41 54 13 254
Table 2. Plasma Creatinine (P-Cr) Levels (Normal or Abnormal) in Patients With Urine Cytology Positive or Negative for Decoy Cells Urine Cytology
Abnormal P-Cr
Normal P-Cr
Total No. of Patients
Positive Negative
25 (26.0%) 36 (13.5%)
71 (74.0%) 230 (86.5%)
96 266
362, 61 (16%) subjects displayed elevated plasma creatinine levels. The (96) patients with urine cytology positive for decoy cells included 25 (26.0%) with elevated creatinine levels, while 36 (13.5%) of the (266) patients with negative urine cytology examinations showed elevated plasma creatinine levels (P ⬍ .05; Table 2). DISCUSSION
The (26.6%) incidence of decoy cells among kidney transplant recipients was concordant with previous reports showing in 20% to 40% rates.6 Similarly, an increased prevalence of decoy cells was observed in men (29.9%) as compared to women (20%), as previously shown.1 In this study we observed a significant relation between increasing age and an higher incidence of decoy cells; there was a significantly higher incidence of decoy cells among patients above versus below 20 years old. Previous investigations had demonstrated increased incidence in the higher age groups, possibly because they become more immunocompromised with the same doses of immunosuppressive medications compared with younger patients, therefore rendering them at increased risk for polyoma virus infection.1 Previous studies demonstrated that the prevalence of polyoma virus infection increases in patients after a prolonged posttransplantation period (median of 9 months),7 a finding confirmed in our study among patients more than 6 months posttransplantation whose prevalence of decoy cells (31.2%) was significantly greater than those with shorter posttransplantation periods (P ⬍ .05). Regarding kidney function in transplanted patients, a relationship between an elevated plasma creatinine value and decoy cells was detected: an abnormal plasma creatinine was detected in 26% of patients having positive urine cytology for decoy cells as compared to those (13.5%) negative for decoy cells on urine cytology. These abnormal plasma creatinine levels were similar to previous studies that showed that patients with BK virus nephropathy showed high serum creatinines that mimicked either tubular necrosis or rejection.1 Despite a low positive predictive value of decoy cells in urine, its absence has a negative predictive value of 100%. As urine cytology is easy to perform with low cost, it is a useful tool to investigate active polyoma virus infection. Considering the risk of graft loss due to polyoma virus infection, it is suggested that routine urine cytology should be used as a screening method for the detection of polyoma virus infection. While negative cytology excludes the presence of polyoma virus nephropathy, the presence of decoy cells in urine cytology can suggest the
URINE CYTOLOGY TO SCREEN FOR PVN
diagnosis of the active viral infection although it is not a definite indication of polyoma virus nephropathy. Decoy cells in the presence of high creatinine represent a good clue for further investigation. REFERENCES 1. Hirsch HH, Steiger J: Polyoma virus BK. Lancet 3:611, 2003 2. Pahari A, Rees L: BK-virus associated renal problems and clinical manifestations. Pediatr Nephrol 18:743, 2003
2925 3. Nickeleit V, Hirsch HH, Binet IF: Polyoma virus infection of renal allograft recipients. J Am Soc Nephrol 10:1080, 1999 4. Nephropathy due to polyoma virus BK. N Engl J Med 18: 342:1361, 2000 (Editorial) 5. Pietropaolo V, Tarato CD: Tran placental transmission of human polyoma virus BK. J Med Virol 56:372, 1998 6. Santos RLS, Manfrinatto JA: Urine cytology as a screening method for polyoma virus active infection. Transplant Proc 36:899, 2004 7. Hliu L, Fresco R, Picken MM: Intranuclear inclusions in allograft kidney. Arch Pathol Lab Med 125:973, 2001