Polyomavirus large T antigen is prevalent in urothelial carcinoma post–kidney transplant

An Unusual Presentation of Metastatic BK Virus-Associated Urothelial Carcinoma Arising in the Allograft, Persisting After Transplant Nephrectomy

We report a 32-year-old male 14 years post-living-related kidney transplant presenting with new-onset hematuria and BK viremia. He was found to have BK virus-associated urothelial carcinoma originating in the renal allograft with locally advanced disease and metastases to multiple sites. He also developed acute T-cell-mediated rejection in the setting of immunosuppression reduction for BK viremia prior to undergoing transplant nephrectomy. Eight months following transplant nephrectomy and immunosuppression cessation, distant metastases persisted with partial response to chemotherapy and immunotherapy. Here, we discuss this unique presentation and compare it with other BK virus-associated allograft carcinomas reported in the literature, in addition to discussing evidence for the role of BK virus in oncogenesis.

Ipsilateral synchronous papillary renal neoplasm with reverse polarity and urothelial carcinoma in a renal transplant recipient: a rare case report with molecular analysis and literature review

BACKGROUND

Renal transplant recipients (RTRs) have a 3- to 5-fold higher risk of developing malignant tumors than the general population, with new malignant tumors after transplantation considered to be the leading cause of death in RTRs. In pathological practice, it is rare for neoplasms with different histology to be located in the same organ. We report the first case of a synchronous papillary renal neoplasm with reverse polarity (PRNRP) and urothelial carcinoma (UC) in the ipsilateral kidney in an RTR. Molecular detection was conducted by next-generation sequencing.

CASE PRESENTATION

A 68-year-old female suffered from uremia 19 years ago and underwent renal transplantation (RT) after receiving dialysis for 6 months. Hematuria occurred one month ago and an enhanced CT showed that there were two abnormal density foci in the middle and lower parts of the autologous left kidney. A laparoscopic left nephrectomy and ureterectomy were performed. Gross examination revealed a mass (I) in the left renal parenchyma, 2*1.8*1.5 cm in size, that protruded from the renal capsule, and a cauliflower-like mass (II), 5*2.5*2 cm in size, adjacent to the mass (I). Microscopic findings revealed these lesions were PRNRP and UC, respectively. PCR analysis revealed a KRAS gene mutation (G12D in exon 2) in the PRNRP, while NGS analysis revealed FGFR3 (S249C in exon 7) and KDM6A (Q271Ter in exon 10 and A782Lfs in exon 17) mutations in the UC.

CONCLUSIONS

We report here for the first time an extraordinarily rare case of synchronous renal tumors of a PRNRP and UC in the ipsilateral kidney of an RTR. We identified simultaneous KRAS, FGFR3, and KDM6A mutations in two different renal masses in the ipsilateral kidney. Pathologic assessment with comparative molecular analysis of mutational profiles facilitates tumor studies after RT and may be of great value in clinical management strategies.

BK Polyomavirus-Associated Urothelial Carcinoma of the Bladder with a Background of BK Polyomavirus Nephropathy in a Kidney Transplant Recipient

Renal transplant recipients are at increased risk for the development of a malignant neoplasm. Polyomavirus-associated urothelial carcinoma is a rare tumor that occurs in renal transplant recipients, with approximately 41 cases reported since 2002. It accounts for 27-31% of all post-transplant urothelial carcinomas and develops at an average of 8.5 years after transplantation. Histologically, it shows high-grade urothelial carcinoma (95.1%) with a high frequency of glandular differentiation and micropapillary structures (58.5%) and positive immunohistochemistry for polyomavirus large T antigen, p53 (92.9%), and p16 (100%). We encountered a case of BK polyomavirus (BKPyV)-associated urothelial carcinoma of the bladder diagnosed 54 months after kidney transplantation. Histologically, it was a high-grade urothelial carcinoma with micropapillary features, and immunohistochemically, it was diffusely positive for polyomavirus large T antigen, p16, and p53. BKPyV DNA and mRNA for BKPyV large T antigen have been identified in tissues using real-time polymerase chain reaction. The same sequence of the BKPyV VP1 genome hypervariable region was detected in both transplanted kidney tissue with polyomavirus nephropathy and urothelial carcinoma tissue, suggesting that polyomavirus-associated urothelial carcinoma developed in a background of persistent polyomavirus nephropathy. This case showed typical histological features and was detected and treated at an earlier stage than has been reported. It is important to keep in mind that polyomavirus-associated urothelial carcinoma can develop early after transplantation and might be associated with polyomavirus nephropathy. Because of its rapidly progressive nature, careful follow-up with urine cytology and cystoscopy is necessary. We report this case with a literature review.

Anterior pelvic exenteration and synchronous bilateral nephroureterectomy for BK polyoma virus induced urothelial carcinoma of the bladder: A case report

BK polyoma virus (BKV) is a known risk factor for the development of urothelial carcinoma. There is currently limited data on the management of BKV-induced urothelial carcinoma (BUC) of the bladder, with available data limited to case reports. It remains debatable whether radical cystectomy (RC) with removal of the native urinary tract or RC alone is the most optimal management for BUC of the bladder. BKV-induced urothelial carcinoma is rare, and its management is challenging in immunocompromised patients such as that of post-transplant patients. This case report provides additional insight into a rare disease, the management of which still lacks established guidelines and remains debatable.

Urothelial carcinoma of the graft kidney with molecular analyses: a rare case report

Background

Malignancy after transplantation is a leading cause of death among kidney transplant recipients. However, donor-derived malignancies are rare. We report a case of a high grade papillary urothelial carcinoma arising in a transplanted kidney.

Case presentation

A 62-year-old female who received a kidney transplantation more than 30 years ago presented with urinary tract infection, acute renal failure, and hydronephrosis of the transplant kidney. Anterograde nephrostogram showed a large filling defect in the lower pole of the transplant kidney and in the proximal 3–4 cm of the ureter. A biopsy from the renal pelvic mass showed a high grade urothelial carcinoma. She underwent an anterior exenteration, resection of both transplant and native kidneys and bilateral pelvic lymph node dissection. Pathologic examination showed a high grade papillary urothelial carcinoma which appeared to arise in the pelvis of the graft kidney, involve the graft ureter and native urinary bladder. The tumor had metastasized to one left obturator lymph node but spared the two native kidneys and ureters. Short tandem repeat (STR) analysis confirmed the tumor to be of donor origin. Next-generation sequencing identified amplification of TERT and loss of CDKN2A/CDKN2B in the primary tumor.

Conclusion

While it is known that transplant recipients have an increased risk of urothelial carcinoma compared to the general population, the lack of the well-documented risk factors, such as older age at transplantation, BK polyomavirus infection, and prolonged post-transplantation history and dissemination of the tumor in this case shed light on the de novo tumorigenesis of the graft kidney within the host microenvironment. Amplification of Telomerase reverse transcriptase (TERT) and loss of cyclin dependent kinase inhibitor 2A/2B (CDKN2A/CDKN2B) detected in the tumor by next gene sequencing suggests that they may play an important role in this case.

Management of de-novo urothelial carcinoma in transplanted patients

PURPOSE OF REVIEW

The aim of this article is to review incidence, risk factors, and optimal management of de-novo urothelial carcinoma in transplant recipients.

RECENT FINDINGS

There is a two to three-fold increased risk for de-novo malignant tumors after solid-organ transplantation, but there is currently no consensus regarding optimal management of de-novo urothelial carcinoma in transplanted patients. Known risk factors include polyomavirus BK, aristolochic acid, and smoking. Data suggest a higher rate of high-grade tumors, as well as predominantly higher stage at primary diagnosis, for both NMIBC and muscle-invasive bladder cancer (MIBC). Treatment for NMIBC includes TURB, mitomycin, and Bacille de Calmette-Guérin instillation with special concern to the immunosuppressive regime. Treatment of MIBC or advanced urothelial carcinoma includes radical cystectomy with chemotherapy if the patient is eligible. A screening should be performed in all transplant recipients, to allow early diagnosis.

SUMMARY

De-novo urothelial carcinoma in transplant recipients is more frequent than in the general population and these tumors were more likely to be high-grade tumors and diagnosed at an advanced stage. There is very little information available on the optimal treatment for these patients. However, aggressive treatment and a strict management according the given recommendations are of the utmost importance.

Resolution of a High Grade and Metastatic BK Polyomavirus-Associated Urothelial Cell Carcinoma Following Radical Allograft Nephroureterectomy and Immune Checkpoint Treatment: A Case Report

BACKGROUND

BK viral infection in the posttransplant setting continues to cause serious morbidity with effects ranging from allograft nephropathy and dysfunction to urothelial malignancy.

RESULTS

In this report, we present a patient that developed BK-associated nephropathy and, 6 years later, locally advanced urothelial malignancy in the renal allograft with nodal, muscle, and extremity involvement. Following radical allograft nephroureterectomy, he was treated with palliative radiation and the immune checkpoint inhibitor atezolizumab. Follow-up imaging at 1 year demonstrated radiographic complete response.

CONCLUSIONS

This report supports the growing body of evidence supporting the association of urothelial malignancy and BK virus infection in renal transplant recipients. Further, it highlights the novel application of immune checkpoint inhibitors in the treatment of advanced posttransplant malignancy, in particular when the allograft is removed and the tumor is possibly of donor origin.

Variant morphology and random chromosomal integration of BK polyomavirus in posttransplant urothelial carcinomas

BK polyomavirus (BKPyV) causes major complications in solid organ transplant recipients but little is known about its role in the development of urothelial carcinoma (UC) during immunosuppression. Immunohistochemistry (IHC) screening for polyomavirus large T antigen (LTag) was performed in 94 micropapillary UC (MPUC), 480 unselected UC, 199 muscle invasive UC (including 83 UC with variant differentiation), 76 cases of plasmocytoid, nested and large nested UC and 15 posttransplant UC. LTag expressing UC were reevaluated regarding their histomorphological features and characterized by IHC for p53 and HER2, chromogenic in situ hybridization for HER2 and SNaPshot analysis of the TERT promoter and HRAS. Real-time PCR and next generation sequencing (NGS) were performed to search for BKPyV-DNA and for variants in the tumor and viral genomes. We detected five LTag expressing UC which were diagnosed between 2 and 18 years after kidney (n = 4) or heart (n = 1) transplantation. 89 MPUC without history of organ transplantation and overall 755 UC (including cases with variant histology) were LTag negative. Of the five LTag expressing UC, three were MPUC, one showed extensive divergent differentiation with Mullerian type clear cell carcinoma, and one displayed focal villoglandular differentiation. All five tumors had aberrant nuclear p53 expression, 2/5 were HER2-amplified, and 3/5 had TERT promoter mutations. Within the 50 most common cancer related genes altered in UC we detected very few alterations and no TP53 mutations. BKPyV-DNA was present in 5/5 UC, chromosomal integration of the BKPyV genome was detectable in 4/5 UC. Two UC with BKPyV integration showed small deletions in the BKPyV noncoding control region (NCCR). The only UC without detectable BKPyV integration had a high viral load of human herpesvirus 6 (HHV-6). Our results suggest that LTag expression of integrated BKPyV genomes and resulting p53 inactivation lead to aggressive high-grade UC with unusual, often micropapillary morphology.

Clinicopathologic Characterization of Post-Renal Transplantation BK Polyomavirus-Associated Urothelial CarcinomaSingle Institutional Experience

OBJECTIVES

To review rare cases of BK polyomavirus (BKPyV) associated urologic carcinomas in kidney transplant recipients at one institution and in the literature.

METHODS

We describe the clinicopathologic features of BKPyV-associated urologic carcinomas in a single-institution cohort.

RESULTS

Among 4,772 kidney recipients during 1994 to 2014, 26 (0.5%) and 26 (0.5%) developed posttransplantation urothelial carcinomas (UCs) and renal cell carcinomas (RCCs), respectively, as of 2017. Six (27%) UCs but none of the RCCs expressed large T antigen (TAg). TAg-expressing UCs were high grade with p16 and p53 overexpression (P < .05 compared to TAg-negative UCs). Tumor genome sequencing revealed BKPyV integration and a lack of pathogenic mutations in 50 cancer-relevant genes. Compared to TAg-negative UCs, TAg-expressing UCs more frequently presented at advanced stages (50% T3-T4) with lymph node involvement (50%) and higher UC-specific mortality (50%).

CONCLUSIONS

Post-renal transplantation BKPyV-associated UCs are aggressive and genetically distinct from most non-BKPyV-related UCs.

Cancer in kidney transplant recipients

Cancer is the second most common cause of mortality and morbidity in kidney transplant recipients after cardiovascular disease. Kidney transplant recipients have at least a twofold higher risk of developing or dying from cancer than the general population. The increased risk of de novo and recurrent cancer in transplant recipients is multifactorial and attributed to oncogenic viruses, immunosuppression and altered T cell immunity. Transplant candidates and potential donors should be screened for cancer as part of the assessment process. For potential recipients with a prior history of cancer, waiting periods of 2-5 years after remission - largely depending on the cancer type and stage of initial cancer diagnosis - are recommended. Post-transplantation cancer screening needs to be tailored to the individual patient, considering the cancer risk of the individual, comorbidities, overall prognosis and the screening preferences of the patient. In kidney transplant recipients diagnosed with cancer, treatment includes conventional approaches, such as radiotherapy and chemotherapy, together with consideration of altering immunosuppression. As the benefits of transplantation compared with dialysis in potential transplant candidates with a history of cancer have not been assessed, current clinical practice relies on evidence from observational studies and registry analyses.

Molecular profiling of clear cell adenocarcinoma of the urinary tract

Clear cell adenocarcinoma (CCA) of the urinary tract is a rare type of malignancy whose molecular profiles remain undefined. Here we reported an integrated clinicopathologic and molecular profiling analysis of four cases of clear cell adenocarcinoma arising in the urethra or the bladder. Utilizing a clinically validated 130-gene exon-sequencing assay, we identified recurrent pathogenic PIK3CA (p. E545K) and KRAS (p.G12D) variants in three of four (75%) of the cases. In addition, an APC variant (P.S2310X), a TP53 variant (p.R273C), and a MYC amplification event were identified. The only CCA case without either PIK3CA or KRAS variants has a distinct pathogenesis through BK virus, demonstrated by positive BK virus PCR and SV40 immunohistochemistry. The novel finding of recurrent variants in the PI3K/AKT/mTOR pathway provides not only insights into oncogenesis but also potential clinical therapeutic targets for patients with clear cell adenocarcinoma of the urinary tract.

Bladder Carcinoma Associated with BK Virus in a Renal Allograft Recipient

Bladder carcinoma is a relatively rare carcinoma reported in renal allograft recipients. While many oncogenic viruses have been implicated as causative factors for certain malignancies, questions have been raised about possible role of BK virus in pathogenesis of urothelial cancers. In this report, we have described a patient who developed BK virus nephropathy followed 3 years later by bladder carcinoma. Interestingly, while the tumor tissue demonstrated BK virus, the adjacent normal urothelium was stained negative for BK virus. Considering the viral potential to inhibit tumor suppressors and its differential localization within tumor tissue, it is possible that the virus contributes to tumorigenesis.

BK polyomavirus in solid organ transplantation-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

The present AST-IDCOP guidelines update information on BK polyomavirus (BKPyV) infection, replication, and disease, which impact kidney transplantation (KT), but rarely non-kidney solid organ transplantation (SOT). As pretransplant risk factors in KT donors and recipients presently do not translate into clinically validated measures regarding organ allocation, antiviral prophylaxis, or screening, all KT recipients should be screened for BKPyV-DNAemia monthly until month 9, and then every 3 months until 2 years posttransplant. Extended screening after 2 years may be considered in pediatric KT. Stepwise immunosuppression reduction is recommended for KT patients with plasma BKPyV-DNAemia of >1000 copies/mL sustained for 3 weeks or increasing to >10 000 copies/mL reflecting probable and presumptive BKPyV-associated nephropathy, respectively. Reducing immunosuppression is also the primary intervention for biopsy-proven BKPyV-associated nephropathy. Hence, allograft biopsy is not required for treating BKPyV-DNAemic patients with baseline renal function. Despite virological rationales, proper randomized clinical trials are lacking to generally recommend treatment by switching from tacrolimus to cyclosporine-A, from mycophenolate to mTOR inhibitors or leflunomide or by the adjunct use of intravenous immunoglobulins, leflunomide, or cidofovir. Fluoroquinolones are not recommended for prophylaxis or therapy. Retransplantation after allograft loss due to BKPyV nephropathy can be successful if BKPyV-DNAemia is definitively cleared, independent of failed allograft nephrectomy.

Nucleic Acid Tests for BK Polyomavirus Is Critical in Renal Transplant Recipients

This study evaluates the incidence of BK polyomavirus (BKV) and prognosis of BKV infection in kidney transplant recipients (KTRs) who received transplantation in our hospital before and after regular BKV nucleic acid test (NAT) was implemented.

METHODS

The study included 74 KTRs who received a single kidney either from standard- or expanded-criteria deceased donor between March 2011 and March 2017. BKV NATs were regularly checked in 26 patients (group 1) in the first posttransplant year in accordance with current guidelines since NAT was implemented in our laboratory in 2014. We retrospectively compared 48 KTRs (group 2) who either received NAT when necessary in another laboratory or were not checked before 2014.

RESULTS

There was no significant difference in patient characteristics between groups. BKV viruria were confirmed in 8 of 26 (30.8%) group 1 patients, whereas only 2 of 48 (4.2%) BKV infections were confirmed in group 2. None of the BKV(+) KTRs in group 1 developed BK polyomavirus-associated nephropathy (BKVAN), whereas 2 BKV(+) patients (100%) of group 2 developed BKVAN, which indicates renal function deterioration and biopsy-validated nephropathy. There was no significant difference in graft survival and renal function between the 2 groups.

CONCLUSIONS

The risk of BKV infection is considerably higher in KTRs using NAT. Because there is no approval treatment, early diagnosis of BKV infection and early reduction of immunosuppression agents is critical for KTRs. Implementation of regular BKV NAT is mandatory before BKVAN and malignant neoplasms develop.

The two-faced nature of BK polyomavirus: lytic infection or non-lytic large-T-positive carcinoma

In immunocompromised patients, reactivation of latent BK polyomavirus (BKPyV) can cause disease with lytic infections of the kidneys and the lower urinary tract. Emerging evidence also links BKPyV to oncogenesis and high‐grade intrarenal and transitional cell carcinomas. These neoplasms strongly express polyomavirus large‐T antigen as a defining feature; that is, they are ‘large‐T‐positive carcinomas’. Such neoplasms arise in immunocompromised patients, typically in renal allograft recipients, and preferentially in tissues harbouring latent BKPyV. In recent articles in this journal, it was shown that tumour cells harbour replication‐incompetent clonal BKPyV. The virus can be truncated and randomly integrated into the genome, and/or it can be mutated in an episomal state. Truncation and/or deletions in the BKPyV non‐coding control region can hamper late viral gene expression, replication, and cell lysis, while facilitating overexpression of early genes, including that encoding large‐T. Biologically active fusion proteins or alterations in human tumour suppressor or promoter function have not been described so far, making uncontrolled large‐T gene expression in non‐lytically infected cells a prime suspect for neoplastic transformation. Current concepts of BKPyV‐induced disease, including recent reports from this journal, are discussed, and evolving paradigms of BKPyV‐associated oncogenesis are highlighted. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Risk factors associated with post-kidney transplant malignancies: an article from the Cancer-Kidney International Network

In kidney transplant recipients, cancer is one of the leading causes of death with a functioning graft beyond the first year of kidney transplantation, and malignancies account for 8-10% of all deaths in the USA (2.6 deaths/1000 patient-years) and exceed 30% of deaths in Australia (5/1000 patient-years) in kidney transplant recipients. Patient-, transplant- and medication-related factors contribute to the increased cancer risk following kidney transplantation. While it is well established that the overall immunosuppressive dose is associated with an increased risk for cancer following transplantation, the contributive effect of different immunosuppressive agents is not well established. In this review we will discuss the different risk factors for malignancies after kidney transplantation.

Characterization of BK Polyomaviruses from Kidney Transplant Recipients Suggests a Role for APOBEC3 in Driving In-Host Virus Evolution

BK polyomavirus (BKV) frequently causes nephropathy (BKVN) in kidney transplant recipients (KTRs). BKV has also been implicated in the etiology of bladder and kidney cancers. We characterized BKV variants from two KTRs who developed BKVN followed by renal carcinoma. Both patients showed a swarm of BKV sequence variants encoding non-silent mutations in surface loops of the viral major capsid protein. The temporal appearance and disappearance of these mutations highlights the intra-patient evolution of BKV. Some of the observed mutations conferred resistance to antibody-mediated neutralization. The mutations also modified the spectrum of receptor glycans engaged by BKV during host cell entry. Intriguingly, all observed mutations were consistent with DNA damage caused by antiviral APOBEC3 cytosine deaminases. Moreover, APOBEC3 expression was evident upon immunohistochemical analysis of renal biopsies from KTRs. These results provide a snapshot of in-host BKV evolution and suggest that APOBEC3 may drive BKV mutagenesis in vivo.

High grade infiltrative adenocarcinomas of renal cell origin: New insights into classification, morphology, and molecular pathogenesis

Collecting duct carcinoma was described over 30 years ago as a renal tumor, based in the medullary collecting system, with tubulopapillary morphology, prominent infiltrative growth, and stromal desmoplasia. While diagnostic workup has always emphasized exclusion of upper tract urothelial carcinoma and metastatic adenocarcinoma to the kidney, the molecular era of renal cell carcinoma classification has enabled recognition of and provided tools for diagnosis of new entities in this morphologic differential. In this review, we consider these developments, with emphasis on renal medullary carcinoma, closely related renal cell carcinoma, unclassified with medullary phenotype, and fumarate hydratase-deficient renal cell carcinoma. Integration of ancillary studies with suggestive patterns of morphology is emphasized for practical implementation in contemporary diagnosis, and several emerging tumor types in the morphologic differential are presented.

Human Polyomavirus Is Associated With Earlier Onset of Upper Urinary Tract Urothelial Carcinoma in Patients After Kidney Transplantation

OBJECTIVES

Polyomavirus has been reported to be oncogenic due to viral integration into the human genome. A relatively high prevalence of upper urinary tract urothelial carcinoma (UTUC) was noted after kidney transplantation (KT) in Taiwan. However, little was known about the impact of polyomavirus on the urothelial cancer behavior. Therefore, the aim of this study is to analyze the characteristics of polyomavirus-related UTUC after KT.

METHODS

From 2005 to 2014, 27 patients were found to have UTUCs after KT. All the patients underwent standard nephroureterectomy. Detailed perioperative parameters were obtained from chart records. A qualified pathologist who is blinded to the clinical outcome examined large T antigen expression and pathological features. All the patients were divided into two groups according to positive or negative expression of large T antigen.

RESULTS

In the patient demography, a significantly younger median age was found in patients with large T antigen-positive UTUCs compared with the negative control group (48.1 ± 8.3 years versus 54.6 ± 4.1 years, respectively, P = .013). As for the pathological features and oncologic outcome, there were no obvious differences between these two groups. Non-organ-confined status and positive lymphovascular invasion are prognostic factors associated with systemic disease recurrence (P = .017 and .001, respectively).

CONCLUSIONS

Although UTUC commonly develops in the elderly, earlier onset of post-KT UTUCs was observed especially in patients with positive large T antigen expression in our cohort. This preliminary result provides valuable experience suggesting more frequent upper urinary tract screening for polyomavirus infected patients after KT in Taiwan.

Polyomavirus Replication and Smoking Are Independent Risk Factors for Bladder Cancer After Renal Transplantation

BACKGROUND

Solid organ transplant recipients are at increased risk for developing malignancies. Polyomaviruses (PV) have been historically associated with experimental tumor development and recently described in association with renourinary malignancies in transplant patients. The aim of this study was to investigate the relationship between PV replication and smoking, and the development of malignant neoplasms in kidney transplant recipients.

METHODS

A retrospective case-control study was conducted for PV replication in all kidney biopsies and urine cytologies performed between 1998 and 2014 from kidney transplant recipients at the University of Maryland Medical Center. Polyomavirus-positive patients (n = 943) were defined as having any of the following: a kidney biopsy with PV associated nephropathy, any urine cytology demonstrating "decoy" cells, and/or significant polyomavirus BK viremia. Polyomavirus-negative matched patients (n = 943) were defined as lacking any evidence of PV replication. The incidence of malignancy (excluding nonmelanoma skin tumors) was determined in these 1886 patients and correlated with demographic data and history of smoking.

RESULTS

There was a 7.9% incidence of malignant tumors after a mean posttransplant follow-up of 7.9 ± 5.4 years. Among all cancer subtypes, only bladder carcinoma was significantly associated with PV replication. By multivariate analysis, only PV replication and smoking independently increased the risk of bladder cancer, relative risk, 11.7 (P = 0.0013) and 5.6 (P = 0.0053), respectively.

CONCLUSIONS

The findings in the current study indicate that kidney transplant recipients with PV replication and smoking are at particular risk to develop bladder carcinomas and support the need for long-term cancer surveillance in these patients.

An Unexpected Surge in Plasma BKPyV Viral Load Heralds the Development of BKPyV-Associated Metastatic Bladder Cancer in a Lung Transplant Recipient With BKPyV Nephropathy

We report a lung transplant recipient who developed BK polyoma virus (BKPyV) DNAemia and BKPyV nephropathy. With careful management of his immunosuppression he achieved significant reduction in BKPyV DNAemia and stabilization of his kidney function. He later developed a high-grade bladder cancer and shortly thereafter he experienced a major upsurge in the level of BKPyV DNAemia that coincided with the discovery of hepatic metastasis. Retrospectively, the bladder cancer and the hepatic secondary tumor stained uniformly for SV40 large T antigen, and the BKPyV DNA sequences identified in plasma corresponded to BKPyV DNA within hepatic tissue, indicating that the spike in BKPyV load was likely derived from the circulating tumor cells or cell-free tumor DNA following metastases of a BKV-associated cancer. To the best of our knowledge, this is the first description of a surge in BKPyV load in a patient with controlled BKPyVN that heralded the appearance of a metastatic urothelial malignancy. This report discusses the literature on BKPyV-associated malignancies and the possibility that unexplained increases in BKPyV DNAemia may be a biomarker for metastatic BKPyV-related urothelial cancer.

Renal cell carcinoma in kidney allografts: histologic types, including biphasic papillary carcinoma

Kidney transplant recipients are at increased risk for malignancy, with about 5% incidence of cancer in native end-stage kidneys. Carcinoma in the renal allograft is far less common. Prior studies have demonstrated a propensity for renal cell carcinomas (RCCs) of papillary subtypes in end-stage kidneys, and perhaps in allograft kidneys, but most allograft studies lack detailed pathologic review and predate the current classification system. We reviewed our experience with renal carcinoma in kidney allografts at 2 academic centers applying the International Society of Urological Pathology classification, informed by immunohistochemistry. The incidence of renal allograft carcinoma was about 0.26% in our population. Of 12 allograft carcinomas, 6 were papillary (50%), 4 were clear cell (33%), 1 was clear cell (tubulo)papillary, and 1 chromophobe. Two of the papillary carcinomas had distinctive biphasic glomeruloid architecture matching the newly named "biphasic squamoid alveolar" pattern and were difficult to classify on core biopsies. The 2 cell types had different immunophenotypes in our hands (eosinophilic cells: RCC-/CK34betaE12+ weight keratin +/cyclin D1+; clear cells: RCC+/cytokeratin high molecular weight negative to weak/cyclin D1-). None of the patients experienced cancer recurrences or metastasis. Our study confirms the predilection for papillary RCCs in kidney allografts and highlights the occurrence of rare morphologic variants. Larger studies are needed with careful pathologic review, which has been lacking in the literature.