Kidney transplantation from living donor with monolateral renal artery fibromuscular dysplasia using a cryopreserved iliac graft for arterial reconstruction: a case report and review of the literature.

BACKGROUND: Aging and mortality of patients on waiting lists for kidney transplantation have increased, as a result of the shortage of organs available all over the world. Living donor grafts represent a significant source to maintain the donor pool, and resorting successfully to allografts with arterial disease has become a necessity. The incidence of renal artery fibromuscular dysplasia (FMD) in potential living renal donors is reported to be 2-6%, and up to 4% of them present concurrent extra-renal involvement. CASE PRESENTATION: We present a case of renal transplantation using a kidney from a living donor with monolateral FMD. Resection of the affected arterial segment and its subsequent replacement with a cryopreserved iliac artery graft from a deceased donor were performed. No intraoperative nor post-operative complications were reported. The allograft function promptly resumed, with satisfying creatinine clearance, and adequate patency of the vascular anastomoses was detected by Doppler ultrasounds. CONCLUSION: Literature lacks clear guidelines on the eligibility of potential living renal donors with asymptomatic FMD. Preliminary assessment of the FMD living donor should always rule out any extra-renal involvement. Whenever possible, resection and reconstruction of the affected arterial segment should be taken into consideration as this condition may progress after implantation.

Histopathology and Long-Term Outcome of Kidneys Transplanted From Donors With Severe Acute Kidney Injury.

BACKGROUND: Acute kidney injury is a treatable entity although difficult to recognize without diagnostic biopsy. We investigated the potential association between clinically defined deceased donors and acute kidney injury with preimplantation histological findings and recipient outcomes. METHODS: Kidney biopsies from donors were classified using the Acute Kidney Injury Network criteria and assessed for percentage glomerulosclerosis, tubular atrophy, interstitial fibrosis, and vascular narrowing with the Remuzzi score and for acute tubular necrosis. Differences in incidence rates of delayed graft function (DGF) and cumulative rejection episodes were compared between recipients transplanted with normal and 3 levels of acute kidney injury using the analysis of variance with Bonferroni correction ( P = .0012). RESULTS: Sixteen out of 335 donors showed a severe acute kidney injury level 3 with a median serum creatinine of 458 µmol/L. Fourteen (88%) had 0-3 Remuzzi score and were used for single kidney transplantation and 2 (12%) were used for dual kidney transplantation (score: 4-6). Recipients who received a kidney from a donor with level 3 acute kidney injury had a higher percentage of DGF (47%) without statistical significance ( P = .008). The rate of cumulative rejection (45%) at 2 years was not significantly increased ( P = .09). CONCLUSIONS: Recipients receiving level 3 acute kidney injury kidneys, selected with Remuzzi histopathological score and acute tubular necrosis assessment, had a greater incidence of DGF but a similar long-term cumulative rejection compared to no injury and level 1 and level 2 acute kidney injury donors. The application of the histopathological examination allowed expansion of the kidney donor pool.

Long-term outcome of renal transplantation from octogenarian donors: A multicenter controlled study.

To assess whether biopsy-guided selection of kidneys from very old brain-dead donors enables more successful transplantations, the authors of this multicenter, observational study compared graft survival between 37 recipients of 1 or 2 histologically evaluated kidneys from donors older than 80 years and 198 reference-recipients of non-histologically evaluated single grafts from donors aged 60 years and younger (transplantation period: 2006-2013 at 3 Italian centers). During a median (interquartile range) of 25 (13-42) months, 2 recipients (5.4%) and 10 reference-recipients (5.1%) required dialysis (crude and donor age- and sex-adjusted hazard ratio [95% confidence interval] 1.55 [0.34-7.12], P = .576 and 1.41 [0.10-19.54], P = .798, respectively). Shared frailty analyses confirmed similar outcomes in a 1:2 propensity score study comparing recipients with 74 reference-recipients matched by center, year, donor, and recipient sex and age. Serum creatinine was similar across groups during 84-month follow-up. Recipients had remarkably shorter waiting times than did reference-recipients and matched reference-recipients (7.5 [4.0-19.5] vs 36 [19-56] and 40 [24-56] months, respectively, P < .0001 for both comparisons). Mean (± SD) kidney donor risk index was 2.57 ± 0.32 in recipients vs 1.09 ± 0.24 and 1.14 ± 0.24 in reference-recipients and matched reference-recipients (P < .0001 for both comparisons). Adverse events were similar across groups. Biopsy-guided allocation of kidneys from octogenarian donors permits further expansion of the donor organ pool and faster access to a kidney transplant, without increasing the risk of premature graft failure.

Are there any relations among transplant centre volume, surgical technique and anatomy for donor graft selection? Ten-year multicentric Italian experience on mini-invasive living donor nephrectomy.

BACKGROUND: Selection of the right or left living donor kidney for transplantation is influenced by many variables. In the present multi centric study including 21 Italian transplant centres, we evaluated whether centre volume or surgical technique may influence the selection process. METHODS: Intra- and perioperative donor data, donor kidney function, and recipient and graft survival were collected among 693 mini-invasive living donor nephrectomies performed from 2002 to 2014. Centre volume (LOW, 1-50 cases; HIGH, >50 cases) and surgical technique (FULL-LAP, full laparoscopic and robotic; HA-LAP, hand-assisted laparoscopy; MINI-OPEN, mini-lumbotomy) were correlated with selection of right or left donor kidney and with donor and recipient outcome. RESULTS: HIGH-volume centres retrieved a higher rate of donor right kidneys (29.3% versus 17.6%, P < 0.01) with single artery (83.1% versus 76.4%, P < 0.05) compared with LOW-volume centres. Surgical technique correlated significantly with rate of donor right kidney and presence of multiple arteries: MINI-OPEN (53% and 13%) versus HA-LAP (29% and 22%) versus FULL-LAP (11% and 23%), P < 0.001 and P < 0.05, respectively. All donors had an uneventful outcome; donor bleeding was more frequent in LOW-volume centres (4% versus 0.9%, P < 0.05). CONCLUSIONS: Centre volume and surgical technique influenced donor kidney side selection. Donor nephrectomy in LOW-volume centres was associated with higher risk of donor bleeding.

Rapid screening for malignancy in organ donors: 15-year experience with the Verona "Alert" protocol and review of the literature.

BACKGROUND: Prevention of transmission of malignancy from donors to recipients is an aim of donor assessment. We report the most stringent interpretation of the Italian National Guidelines. METHODS: A two-step ALERT process was used: ALERT1 consisting of clinical, radiological, and laboratory tests; ALERT2, consisting of intraoperative assessment in suspicious lesions. RESULTS: Four hundred of 506 potential deceased donors entered the ALERT system. Forty-one of 400 (10%) donors were excluded due to unacceptable risk of transmission. Of the remaining 359 193 required histopathology, which excluded malignancy or determined acceptable risk in 161/193 (83%). Thirty-five malignancies were identified: 19 (54%) at ALERT1, four (11%) at ALERT2, nine (26%) picked up at ALERT1 and confirmed by ALERT2. Three (9%) were missed by ALERT and diagnosed at postmortem examination. Prostate (n=12%, 34%) and renal cell (n=7%, 20%) were the most frequent carcinomas. The majority (92%) of prostate adenocarcinomas were of low risk and donation proceeded compared to 43% of renal carcinomas. Four renal carcinomas, two breast carcinomas, and a single case of nine different malignancies excluded donation. Positive ALERT donors had statistically more malignant reports than negative ALERT donors (P=<.05). CONCLUSION: Histopathology is an essential component of the multidisciplinary assessment of donors.

Direct Revascularization with Autotransplant Technique for a True Aneurysm of the Renal Artery 20 Years after Kidney Transplantation.

BACKGROUND: True degenerative aneurysm of renal artery represents a very rare evolution in kidney transplantation. The cases presented in the literature are usually perianastomotic or mycotic pseudoaneurysm related to surgical technical defects or local infections. CASE REPORT: Herewith, we present the case of a voluminous true aneurysm developed in a young patient transplanted at our hospital 20 years before. All follow-up ultrasounds were always normal until the last disclosing a voluminous aneurysm of the transplanted renal artery. The subsequent angio-CT-scan confirmed the presence of a 52-mm saccular dilatation of the renal artery. For the complex anatomy, the endovascular approach was excluded, and a surgical revascularization was staged. We treated this lesion with the autotransplant technique, preserving the transplanted kidney, resecting the aneurysm, and performing a direct anastomosis after cold perfusion of the kidney. CONCLUSIONS: The autotransplant technique demonstrated to be a safe and effective approach in this challenging and very unusual situation.

Optimizing utilization of kidneys from deceased donors over 60 years: five-year outcomes after implementation of a combined clinical and histological allocation algorithm.

This 5 year observational multicentre study conducted in the Nord Italian Transplant programme area evaluated outcomes in patients receiving kidneys from donors over 60 years allocated according to a combined clinical and histological algorithm. Low-risk donors 60-69 years without risk factors were allocated to single kidney transplant (LR-SKT) based on clinical criteria. Biopsy was performed in donors over 70 years or 60-69 years with risk factors, allocated to Single (HR-SKT) or Dual kidney transplant (HR-DKT) according to the severity of histological damage. Forty HR-DKTs, 41 HR-SKTs and 234 LR-SKTs were evaluated. Baseline differences generally reflected stratification and allocation criteria. Patient and graft (death censored) survival were 90% and 92% for HR-DKT, 85% and 89% for HR-SKT, 88% and 87% for LR-SKT. The algorithm appeared user-friendly in daily practice and was safe and efficient, as demonstrated by satisfactory outcomes in all groups at 5 years. Clinical criteria performed well in low-risk donors. The excellent outcomes observed in DKTs call for fine-tuning of cut-off scores for allocation to DKT or SKT in high-risk patients.

Systemic and nonrenal adverse effects occurring in renal transplant patients treated with mTOR inhibitors.

The mammalian target of rapamycin inhibitors (mTOR-I), sirolimus and everolimus, are immunosuppressive drugs largely used in renal transplantation. The main mechanism of action of these drugs is the inhibition of the mammalian target of rapamycin (mTOR), a regulatory protein kinase involved in lymphocyte proliferation. Additionally, the inhibition of the crosstalk among mTORC1, mTORC2, and PI3K confers the antineoplastic activities of these drugs. Because of their specific pharmacological characteristics and their relative lack of nephrotoxicity, these inhibitors are valid option to calcineurine inhibitors (CNIs) for maintenance immunosuppression in renal transplant recipients with chronic allograft nephropathy. However, as other immunosuppressive drugs, mTOR-I may induce the development of several adverse effects that need to be early recognized and treated to avoid severe illness in renal transplant patients. In particular, mTOR-I may induce systemic nonnephrological side effects including pulmonary toxicity, hematological disorders, dysmetabolism, lymphedema, stomatitis, cutaneous adverse effects, and fertility/gonadic toxicity. Although most of the adverse effects are dose related, it is extremely important for clinicians to early recognize them in order to reduce dosage or discontinue mTOR-I treatment avoiding the onset and development of severe clinical complications.

Outcomes in AB0 Incompatible Living Donor Kidney Transplantation: A Case - Control Study.

Background: Patients waiting for a kidney transplant by far exceed available organs. AB0 incompatible living donor kidney transplantation (AB0i LDKT) represents an additional therapeutic strategy, but with higher risk for complications. We aimed at evaluating outcomes of AB0i LDKTs compared to compatible (AB0c) controls at our Institution. Methods: Retrospective matched case - control study (1:2) comparing AB0i vs. AB0c LDKTs from March 2012 to September 2021. Considered outcomes: graft function, acute rejection, sepsis, CMV infection, BK virus reactivation, death-censored graft survival, patient survival. Results: Seventeen AB0i LDKTs matched to 34 AB0c controls. We found excellent graft function, comparable in the two groups, at all considered intervals, with an eGFR (ml/min/1.73 m2) of 67 vs. 66 at 1 year (p = 0.41), 63 vs. 64 at 3 years (p = 0.53). AB0i recipients had a statistically significant higher incidence of acute rejection, acute antibody-mediated rejection and sepsis within 30 days (p = 0.016; p = 0.02; p = 0.001), 1 year (p = 0.012; p = 0.02; p = 0.0004) and 3 years (p = 0.004; p = 0.006; p = 0.012) after surgery. There was no difference in CMV infection, BK virus reactivation, death-censored graft survival between the two groups. Patient survival was inferior in AB0i group at 1 and 3 years (88.2 vs. 100%; log-rank p = 0.03) due to early death for opportunistic infections. AB0i LDKTs spent longer time on dialysis (p = 0.04) and 82.3 vs. 38.3% controls had blood group 0 (p = 0.003). Conclusions: AB0i LDKT is an effective therapeutic strategy with graft function and survival comparable to AB0c LDKTs, despite higher rates of acute rejection and sepsis. It is an additional opportunity for patients with less chances of being transplanted, as blood group 0 individuals.

Analysis of the 3'UTR of the prostaglandin synthetase-2 (PTGS-2/COX-2) gene in non-melanoma skin cancer after organ transplantation.

To define the potential involvement of polymorphisms in the 3'untranslated region (3'UTR) of the prostaglandin synthetase-2 (PTGS-2) gene to non-melanoma skin cancer (NMSC) predisposition after transplantation, we screened for genetic variant, relevant parts of this region. It contains binding sites for trans-acting factors, an alternative polyadenylation site and putative target sequences for miRNAs. Variant +8473T>C did not appear to play a functional role in the regulation of gene expression in human keratinocyte-transfected cells. In addition to the well-known +8473T>C, we identified four polymorphisms: +8293G>C, +10259T>G, +10267G>A and +10335G>A. No allele frequency differences were observed between cases and controls neither for +8473T>C nor for any of the identified polymorphisms, suggesting that polymorphisms in the 3'UTR of the PTGS2 gene are rare and unlikely to represent risk factor for NMSC after transplantation.

Advantages of Using a Web-based Digital Platform for Kidney Preimplantation Biopsies.

BACKGROUND: In the setting of kidney transplantation, histopathology of kidney biopsies is a key element in the organ assessment and allocation. Despite the broad diffusion of the Remuzzi-Karpinski score on preimplantation kidney biopsies, scientific evidence of its correlation to the transplantation outcome is controversial. The main issues affecting the prognostic value of histopathology are the referral to general on-call pathologists and the semiquantitative feature of the score, which can raise issues of interpretation. Digital pathology has shown very reliable and effective in the oncological diagnosis and treatment; however, the spread of such technologies is lagging behind in the field of transplantation. The aim of our study was to create a digital online platform where whole-slide images (WSI) of preimplantation kidney biopsies could be uploaded and stored. METHODS: We included 210 kidney biopsies collected between January 2015 and December 2019 from the joint collaboration of the transplantation centers of Padua and Verona. The selected slides, stained with hematoxylin and eosin, were digitized and uploaded on a shared web platform. For each case, the on-call pathologists' Remuzzi grades were obtained from the original report, together with the clinical data and the posttransplantation follow-up. RESULTS: The storage of WSI of preimplantation kidney biopsies would have several clinical, scientific, and educational advantages. The clinical utility relies on the possibility to consult online expert pathologists and real-time quality checks of diagnosis. From the perspective of follow-up, the archived digitized biopsies can offer a useful comparison to posttransplantation biopsies. In addition, the digital online platform is a precious tool for multidisciplinary meetings aimed both at the clinical discussion and at the design of research projects. Furthermore, this archive of readily available WSI is an important educational resource for the training of professionals. CONCLUSIONS: Finally, the web platform lays the foundation for the introduction of artificial intelligence in the field of transplantation that would help create new diagnostic algorithms and tools with the final aim of increasing the precision of organ assessment and its predictive value for transplant outcome.

Incidence and clinical predictors of primary opportunistic deep cutaneous mycoses in solid organ transplant recipients: a multicenter cohort study.

BACKGROUND: Primary opportunistic deep cutaneous fungal infections may cause significant morbidity and mortality in solid organ transplant recipients (OTR), but no data exist about their incidence, timing, and clinical predictors in a long-term follow-up. PATIENTS AND METHODS: A series of 3293 consecutive OTR including 1991 kidney, 929 heart, and 373 liver transplant recipients were enrolled. Patients were regularly followed up since time at transplantation (mean 5.5 yr +/-5.9 SD) and primary opportunistic fungal infections registered. Persons-year at risk (PYs), incidence rates (IR), incidence rate ratios (IRR), and 95% confidence intervals were computed. RESULTS: Twenty-two cases of deep cutaneous mycoses were detected, (IR 1.2 cases per 1000 PYs) after a mean follow-up time since transplantation of 2.5 yr +/- 2.0 SD (median 1.8 yr). Six patients had subsequent systemic involvement and three patients died of systemic dissemination. A higher risk for mycoses was observed in the first two yr after transplantation, (IRR 35.9, p < 0.0001), in renal transplant recipients (IRR 5.1 p = 0.030), and in patients transplanted after the age of 50 (IRR 11.5 p = 0.020). CONCLUSIONS: Primary deep cutaneous opportunistic mycoses in OTR occur mainly in the first two yr after transplantation, in renal transplant recipients, and in older patients.

Mortality from cancer is not increased in elderly kidney transplant recipients compared to the general population: a competing risk analysis.

BACKGROUND: The impact of cancer on death of elderly kidney transplant recipients has been extensively investigated, but with conflicting results. Unlike their younger counterparts, in elderly kidney transplant recipients cardiovascular and infectious disease may outweigh cancer in causing the patient's death. METHODS: Using competing risk analysis on a large retrospective cohort of kidney transplant recipients, we estimated the cause-specific cumulative incidence and hazard of death in different age categories and calculated standardized mortality ratios (SMRs) to compare mortality rates with the general population. RESULTS: Six thousand seven hundred eighty-nine kidney transplant recipients were followed-up for a median of 9 years. Ten years after transplantation, in transplant recipients aged 20-39, 40-59, and 60+, the cumulative incidence of cancer-related death was 0.6 (95% confidence interval [CI]: 0.3-1.0), 2.9 (2.3-3.6) and 5.3% (3.5-7.5), whereas the SMR was 9.1 (5.5-15.0), 2.0 (1.6-2.5), and 0.8 (0.6-1.0), respectively. At variance with young recipients, the hazard and the cumulative incidence of cardiovascular-related death in elderly recipients was well above that of cancer-related death. CONCLUSIONS: Relative to the general population, cancer-related death is increased in young but not in elderly kidney transplant recipients because of the more marked increased incidence of competing cause of death in the latter category.

Donor-transmitted cancer in kidney transplant recipients: a systematic review.

The transmission of cancer from a donor organ is a rare event but has important consequences. Aim of this systematic review was to summarize all the published evidence on cancer transmission in kidney recipients. We reviewed published case reports and series describing the outcome of recipients with donor-transmitted cancer until August 2019. A total of 128 papers were included, representing 234 recipients. The most common transmitted cancers were lymphoma (n = 48, 20.5%), renal cancer (42, 17.9%), melanoma (40, 17.1%), non-small cell lung cancer (n = 13, 5.6%), neuroendocrine cancers comprising small cell lung cancer (n = 11, 4.7%) and choriocarcinoma (n = 10, 4.3%). There was a relative lack of glioblastoma and gastrointestinal cancers with only 6 and 5 cases, respectively. Melanoma and lung cancer had the worst prognosis, with 5-years overall survival of 43% and 19%, respectively; while renal cell cancer and lymphomas had a favorable prognosis with 5-years overall survival of 93 and 63%, respectively. Metastasis of cancer outside the graft was the most important adverse prognostic factor. Overall reporting was good, but information on donors' cause of death and investigations at procurement was often lacking. Epidemiology of transmitted cancer has evolved, thanks to screening with imaging and blood tests, as choriocarcinoma transmission have almost abolished, while melanoma and lymphoma are still difficult to detect and prevent.

Pre-implantation kidney biopsy: value of the expertise in determining histological score and comparison with the whole organ on a series of discarded kidneys.

BACKGROUND: Evidence about the reliability of pre-implantation biopsy is still conflicting, depending on both biopsy type and pathologist's expertise. Aim of the study is to evaluate the agreement of general v specialist pathologists and to compare scores on biopsy and whole organs in a set of discarded kidneys. METHODS: 46 discarded kidneys were identified with their corresponding biopsies. The biopsies were reviewed by three general and two specialist pathologists, blinded to the original report, according to Remuzzi score. The intraclass correlation coefficient (ICC) was calculated for both groups. Discarded kidneys were scored according to Remuzzi score by a single specialist pathologist. Biopsies and organs were compared by Wilcoxon signed rank test. Weighted κ coefficients between biopsy and organ scores were also calculated. RESULTS: Specialist pathologists achieved higher values of ICC, reaching excellent or good agreement in most of the parameters, while general pathologists values were mainly fair or good. On whole organs, scores were consistently lower than biopsies, with a significant difference in most of the parameters. Weighted κ coefficient was slight or fair for most of the parameters. CONCLUSIONS: Our data suggests that the creation of a pool of specialist pathologists would improve organ utilization. Moreover, biopsies are not representative of the whole organ. As the Remuzzi score on biopsy is a major reasons for discard, a quota of transplantable kidneys may be erroneously discarded. Refinement in Remuzzi cut-offs based on expert reporting and recognition of sampling error of biopsies in correlation with clinical outcome data should be undertaken.

Incidence and clinical predictors of Kaposi's sarcoma among 1721 Italian solid organ transplant recipients: a multicenter study.

Kaposi's sarcoma (KS) can be a complication of solid organ transplantation, but with an important incidence rate variability in different geographical areas. Here we analyzed the incidence rate, timing and clinical correlates of KS, in a cohort of Italian solid organ transplant recipients from four distinct transplantation centers. A total of 1721 renal, heart and liver transplant recipients were recruited between 1997 and 2004. KS was diagnosed in 40 patients, after a median follow up of 1 year (range 0.8-5.1). Visceral involvement was detected in 7/40 patients. Incidence rate of KS in the whole population was 2.3 cases per 1000 individuals per year. The standardized incidence rate (SIR) for KS in renal transplant recipients was 149.9 (95% CI 103.0-212.0), with the excess risk greater among women (SIR 316.0) than among men (SIR 133.6). In a Cox proportional hazard regression model, age at transplantation equal or older than 30 years and only combined immunosuppressive therapy with mycophenolate mofetil + cyclosporine + prednisolone were independently associated with KS. Italian organ transplant recipients have an increased risk (about 100 times greater) for KS compared to the general population, especially during the first two years after transplantation. Age older than 30 years at transplantation and a more aggressive immunosuppressive regimen were both independent risk factors for the disease.

Digital reporting of whole-slide images is safe and suitable for assessing organ quality in preimplantation renal biopsies.

Digital pathology allows networks of "remote" specialist pathologists to report the findings of preimplantation kidney biopsies. We sought to validate the assessment of preimplantation kidney transplant biopsies for diagnostic purposes using whole-slide images according to the recommendations of the College of American Pathologists. Sixty-two consecutive, previously reported, preimplantation kidney biopsies were scanned using the ScanScope Digital Slide Scanner at 0.5 µm/pixel (20× objective). The slides were assessed for percent glomerulosclerosis, tubular atrophy, interstitial fibrosis and vascular narrowing using the Remuzzi criteria by two pathologists, one using glass slides and the other using the whole-slide images viewed on a widescreen computer monitor. After a 2-week washout period, all of the slides were re-assessed by the same pathologists using the opposite mode of reporting to that used in the first evaluation. Very high glass-digital intraobserver concordance was achieved for the overall score and for individual grades by both pathologists (κ range, 0.841-0.973). The overall scores obtained by both pathologists and using both methods were identical. The times needed to assess the biopsies were 14 minutes when using a light microscope and 18 minutes, including scanning time, which averaged 2 minutes 20 seconds per slide, when using digital microscopy. Digital microscopy is a reliable, fast, and safe method for the assessment of preimplantation kidney biopsies.

De Novo Renal Neoplasia After Kidney Transplantation According to New 2016 WHO Classification of Renal Tumors.

BACKGROUND De novo renal neoplasia developing after kidney transplantation at Verona Kidney Transplant Center were reviewed according to new 2016 WHO Renal Tumor Classification. MATERIAL AND METHODS Primary renal tumors developed in native or transplanted kidneys de novo following renal transplantation were retrieved and histologically reviewed by three expert uropathologists. Immunoexpression of the diagnostic antigens CD13, CD10, CK7, CK34bE12, AMACR, CAIX, AE1/AE3, CK14, GATA-3, HMB-45, cathepsin-k, S100A1, and parvalbumin was assessed. Predictive antigens ph-mTOR and ph-p70S6k were also tested. RESULTS Two thousands and sixteen kidney transplantations have been carried out from 1968-2015. Follow-up was available per 1,646 patients (mean 8.4 years). We observed 16 cases of de novo renal neoplasia arising in patients 16 to 286 months post-transplantation. Nine clear cell, two papillary RCCs and a single case of the new WHO entity denominated "acquired cystic disease-associated RCC" were identified in native kidneys. Another new WHO tumor entity called "clear cell papillary RCC" was diagnosed and a new variant of papillary RCC with diffuse clear cytoplasm was also identified. The majority of tumors were low stage and low grade according to the new ISUP grading system. Seven patients were additionally treated with mTOR inhibitors. Post-cancer follow-up ranged from 62 to 281 months. One patient showed a recurrence (a lung metastases) and died. Of the remaining patients, three died of non-cancer-related causes. CONCLUSIONS The application of the new WHO 2016 classification has importance as it identifies new (18% of tumors) morphotypes that are likely to behave in a less aggressive fashion.