The Banff 2022 Kidney Meeting Work Plan: Data-driven refinement of the Banff Classification for renal allografts.

The XVIth Banff Meeting for Allograft Pathology was held in Banff, Alberta, Canada, from September 19 to 23, 2022, as a joint meeting with the Canadian Society of Transplantation. In addition to a key focus on the impact of microvascular inflammation and biopsy-based transcript analysis on the Banff Classification, further sessions were devoted to other aspects of kidney transplant pathology, in particular T cell-mediated rejection, activity and chronicity indices, digital pathology, xenotransplantation, clinical trials, and surrogate endpoints. Although the output of these sessions has not led to any changes in the classification, the key role of Banff Working Groups in phrasing unanswered questions, and coordinating and disseminating results of investigations addressing these unanswered questions was emphasized. This paper summarizes the key Banff Meeting 2022 sessions not covered in the Banff Kidney Meeting 2022 Report paper and also provides an update on other Banff Working Group activities relevant to kidney allografts.

The Banff 2022 Kidney Meeting Report: Reappraisal of microvascular inflammation and the role of biopsy-based transcript diagnostics.

The XVI-th Banff Meeting for Allograft Pathology was held at Banff, Alberta, Canada, from 19th to 23rd September 2022, as a joint meeting with the Canadian Society of Transplantation. To mark the 30th anniversary of the first Banff Classification, premeeting discussions were held on the past, present, and future of the Banff Classification. This report is a summary of the meeting highlights that were most important in terms of their effect on the Classification, including discussions around microvascular inflammation and biopsy-based transcript analysis for diagnosis. In a postmeeting survey, agreement was reached on the delineation of the following phenotypes: (1) "Probable antibody-mediated rejection (AMR)," which represents donor-specific antibodies (DSA)-positive cases with some histologic features of AMR but below current thresholds for a definitive AMR diagnosis; and (2) "Microvascular inflammation, DSA-negative and C4d-negative," a phenotype of unclear cause requiring further study, which represents cases with microvascular inflammation not explained by DSA. Although biopsy-based transcript diagnostics are considered promising and remain an integral part of the Banff Classification (limited to diagnosis of AMR), further work needs to be done to agree on the exact classifiers, thresholds, and clinical context of use.

Banff 2022 pancreas transplantation multidisciplinary report: Refinement of guidelines for T cell-mediated rejection, antibody-mediated rejection and islet pathology. Assessment of duodenal cuff biopsies and noninvasive diagnostic methods.

The Banff pancreas working schema for diagnosis and grading of rejection is widely used for treatment guidance and risk stratification in centers that perform pancreas allograft biopsies. Since the last update, various studies have provided additional insight regarding the application of the schema and enhanced our understanding of additional clinicopathologic entities. This update aims to clarify terminology and lesion description for T cell-mediated and antibody-mediated allograft rejections, in both active and chronic forms. In addition, morphologic and immunohistochemical tools are described to help distinguish rejection from nonrejection pathologies. For the first time, a clinicopathologic approach to islet pathology in the early and late posttransplant periods is discussed. This update also includes a discussion and recommendations on the utilization of endoscopic duodenal donor cuff biopsies as surrogates for pancreas biopsies in various clinical settings. Finally, an analysis and recommendations on the use of donor-derived cell-free DNA for monitoring pancreas graft recipients are provided. This multidisciplinary effort assesses the current role of pancreas allograft biopsies and offers practical guidelines that can be helpful to pancreas transplant practitioners as well as experienced pathologists and pathologists in training.

Defining the origin, evolution, and immune composition of SDH-deficient renal cell carcinoma.

Succinate dehydrogenase (SDH)-deficient renal cell carcinoma represents a rare subtype of hereditary kidney cancer. Clinical diagnosis can be challenging and there is little evidence to guide systemic therapeutic options. We performed genomic profiling of a cohort of tumors through the analysis of whole genomes, transcriptomes, as well as flow cytometry and immunohistochemistry in order to gain a deeper understanding of their molecular biology. We find neutral evolution after early tumor activation with a lack of secondary driver events. We show that these tumors have epithelial derivation, possibly from the macula densa, a specialized paracrine cell of the renal juxtaglomerular apparatus. They subsequently develop into immune excluded tumors. We provide transcriptomic and protein expression evidence of a highly specific tumor marker, PAPPA2. These translational findings have implications for the diagnosis and treatment for this rare tumor subtype.

Ex vivo delivery of Mirococept: A dose-finding study in pig kidney after showing a low dose is insufficient to reduce delayed graft function in human kidney.

The complement system plays a pivotal role in the pathogenesis of ischemia-reperfusion injury in solid organ transplantation. Mirococept is a potent membrane-localizing complement inhibitor that can be administered ex vivo to the donor kidney prior to transplantation. To evaluate the efficacy of Mirococept in reducing delayed graft function (DGF) in deceased donor renal transplantation, we undertook the efficacy of mirococept (APT070) for preventing ischaemia-reperfusion injury in the kidney allograft (EMPIRIKAL) trial (ISRCTN49958194). A dose range of 5-25 mg would be tested, starting with 10 mg in cohort 1. No significant difference between Mirococept at 10 mg and control was detected; hence the study was stopped to enable a further dose saturation study in a porcine kidney model. The optimal dose of Mirococept in pig kidney was 80 mg. This dose did not induce any additional histological damage compared to controls or after a subsequent 3 hours of normothermic machine perfusion. The amount of unbound Mirococept postperfusion was found to be within the systemic dose range considered safe in the Phase I trial. The ex vivo administration of Mirococept is a safe and feasible approach to treat DGF in deceased donor kidney transplantation. The porcine kidney study identified an optimal dose of 80 mg (equivalent to 120 mg in human kidney) that provides a basis for further clinical development.

Ultrastructure of cell trafficking pathways and coronavirus: how to recognise the wolf amongst the sheep.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has resulted in an urgent need to understand the pathophysiology of SARS-CoV-2 infection, to assist in the identification of treatment strategies. Viral tissue tropism is an active area of investigation, one approach to which is identification of virus within tissues by electron microscopy of post-mortem and surgical specimens. Most diagnostic histopathologists have limited understanding of the ultrastructural features of normal cell trafficking pathways, which can resemble intra- and extracellular coronavirus; in addition, viral replication pathways make use of these trafficking pathways. Herein, we review these pathways and their ultrastructural appearances, with emphasis on structures which may be confused with coronavirus. In particular, we draw attention to the fact that, when using routine fixation and processing, the typical 'crown' that characterises a coronavirus is not readily identified on intracellular virions, which are located in membrane-bound vacuoles. In addition, the viral nucleocapsid is seen as black dots within the virion and is more discriminatory in differentiating virions from other cellular structures. The identification of the viral replication organelle, a collection of membranous structures (convoluted membranes) seen at a relatively low scanning power, may help to draw attention to infected cells, which can be sparse. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Kidney Rejection Following Simultaneous Liver-kidney Transplantation.

BACKGROUND: Donor-specific antibodies are reported to increase the risk of rejection and reduce allograft survival following simultaneous liver-kidney transplantation. Optimal immunosuppression regimens to reduce this risk and to treat rejection episodes are underinvestigated. METHODS: Cohort analysis of the first 27 simultaneous liver-kidney transplant recipients, between 2014 and 2018 at our unit, is performed under a new risk stratification policy. Those with donor-specific antibodies to class II HLA with a mean fluorescence intensity >10 000 are considered high risk for antibody-mediated rejection (AMR). These patients received immunosuppression, which consisted of induction therapy, tacrolimus, mycophenolate mofetil, and prednisolone. All other patients are considered low risk and received tacrolimus and prednisolone alone. RESULTS: Three patients were high risk for rejection, and 2 of these patients developed AMR, which was treated with plasma exchange and intravenous immunoglobulin. At 1 y, their estimated glomerular filtration rate (eGFR) were 50 and 59 mL/min. Two other patients developed AMR, which was similarly treated, and their 1-y eGFR was 31 and 50 mL/min. The overall histologically proven acute rejection rate within the first year was 33%, and median eGFR, for the 27 patients, at 1 y was 52 mL/min and at 2 y was 49 mL/min. CONCLUSIONS: This study confirms that there is a risk of AMR following simultaneous liver-kidney transplantation despite increased immunosuppression. This can be effectively treated with plasma exchange and intravenous immunoglobulin.

Multiparametric Ultrasound of Nonpalpable Focal Testicular Lesions.

Indeterminate nonpalpable focal testicular lesions have emerged as a clinical problem with the increasing use of scrotal ultrasound, particularly in the context of infertility. Conventional morphological ultrasound and color Doppler have been unreliable at differentiating benign from malignant lesions. Multiparametric ultrasound (mpUS) comprises real-time elastography and contrast-enhanced ultrasound as adjunctive tools, and is ready for use in most state-of-the-art ultrasound systems. Initial experience with mpUS from selected specialist centers shows promise for lesion characterization, and potential for affecting management and improving outcomes. This article provides a summary of the existing literature on testicular mpUS, and outlines the clinical context from a urological and histopathological perspective.

Effect of Optimized Immunosuppression (Including Rituximab) on Anti-Donor Alloresponses in Patients With Chronically Rejecting Renal Allografts.

RituxiCAN-C4 combined an open-labeled randomized controlled trial (RCT) in 7 UK centers to assess whether rituximab could stabilize kidney function in patients with chronic rejection, with an exploratory analysis of how B cell-depletion influenced T cell anti-donor responses relative to outcome. Between January 2007 and March 2015, 59 recruits were enrolled after screening, 23 of whom consented to the embedded RCT. Recruitment was halted when in a pre-specified per protocol interim analysis, the RCT was discovered to be significantly underpowered. This report therefore focuses on the exploratory analysis, in which we confirmed that when B cells promoted CD4+ anti-donor IFNγ production assessed by ELISPOT, this associated with inferior clinical outcome; these patterns were inhibited by optimized immunosuppression but not rituximab. B cell suppression of IFNγ production, which associated with number of transitional B cells and correlated with slower declines in kidney function was abolished by rituximab, which depleted transitional B cells for prolonged periods. We conclude that in this patient population, optimized immunosuppression but not rituximab promotes anti-donor alloresponses associated with favorable outcomes. Clinical Trial Registration: Registered with EudraCT (2006-002330-38) and www.ClinicalTrials.gov, identifier: NCT00476164.

Early allograft pancreatectomy-Technical failure or acute pancreatic rejection?

INTRODUCTION: "Technical failure" is still perceived to be a frequent cause of graft loss after pancreas transplantation. However, some early graft losses currently attributed to technical failure could be due to unrecognized acute pancreas rejection (APR). METHODS: We investigated the apparent incidence of APR in cases of early allograft pancreatectomy (EAP) that had previously been attributed to technical failure. We performed an analysis of 198 patients who underwent pancreas transplantation between January 2009 and January 2016 and identified all those with EAP within 90 days of transplantation. Explanted grafts of EAP recipients were re-examined histologically to evaluate for evidence of APR using current Banff criteria. RESULTS: Twenty-three EAPs were identified (11.6%; 23/198). APR was identified histologically in 9 out of the 15 recipients who lost their grafts due to duodenal leaks or recurrent peripancreatic collections, but was not identified in any of the patients whose grafts were lost due to thrombosis or ischemia. INTERPRETATION: Unsuspected APR appears common in the explanted grafts of recipients who have undergone EAP for apparently "technical" reasons. We suggest that EAP should be defined as a technical failure only when APR of the pancreas (or duodenum) has been excluded by histological analysis.

Chronic histological changes in deceased donor kidneys at implantation do not predict graft survival: a single-centre retrospective analysis.

The use of preimplantation kidney biopsies (PIKBs) to aid deceased donor kidney utilization decisions is controversial. Outcomes of transplants that had been biopsied after the decision had been made to implant were analysed, in order to determine the association between chronic histological changes at implantation and graft outcomes. A retrospective analysis of transplants between the year range 2006-2015 was performed. Karpinski scores on biopsies were collected, and graft outcomes were analysed using univariate and multivariable techniques. Also, Karpinski scores from single and dual kidney transplants from older donors were examined to determine if knowledge of the score preoperatively would have altered utilization. Four hundred and eight single kidneys were transplanted. Although kidneys with scores >4 had lower 1- and 3-year median (IQR) estimated glomerular filtration rates (eGFRs) than those scoring 0-4 (51 (37-66) vs. 35 (26-52) ml/min/1.73 m2 , P < 0.001, and 52 (34-64) vs. 35 (24-52) ml/min/1.73 m2 , P < 0.001, respectively), there was no significant association between Karpinski score and death-censored graft survival on univariate or multivariable analyses. The utilization analysis (75 single and 25 dual kidney transplant recipients) suggested that systematic use of PIKBs would have resulted in 29% fewer patients being transplanted. This analysis does not support the systematic use of PIKBs to determine deceased donor kidney utilization.

A 2018 Reference Guide to the Banff Classification of Renal Allograft Pathology.

The Banff Classification of Allograft Pathology is an international consensus classification for the reporting of biopsies from solid organ transplants. Since its initial conception in 1991 for renal transplants, it has undergone review every 2 years, with attendant updated publications. The rapid expansion of knowledge in the field has led to numerous revisions of the classification. The resultant dispersal of relevant content makes it difficult for novices and experienced pathologists to faithfully apply the classification in routine diagnostic work and in clinical trials. This review shall provide a complete and simple illustrated reference guide of the Banff Classification of Kidney Allograft Pathology based on all publications including the 2017 update. It is intended as a concise desktop reference for pathologists and clinicians, providing definitions, Banff Lesion Scores and Banff Diagnostic Categories. An online website reference guide hosted by the Banff Foundation for Allograft Pathology (www.banfffoundation.org) is being developed, which will be updated with future refinement of the Banff Classification from 2019 onward.

Fertility preservation in testicular cancer - predictors of spermatogenesis.

OBJECTIVES: To determine the frequency of spermatogenesis in patients with testicular cancer and to assess for any predictors of spermatogenesis. PATIENTS AND METHODS: We retrospectively reviewed 103 testicular germ cell tumours (TGCTs) in men who underwent radical orchidectomy conducted at Guy's Hospital, London, between 2011 and 2015. Primary outcome measures included: the presence and characteristics of spermatogenesis (widespread/focal/proximity to tumour). Secondary outcome measures included: the presence of testicular microlithiasis, tumour characteristics (size, stage, and type), and tumour markers. Secondary outcome measures as potential predictors of spermatogenesis were assessed using univariate and multivariate logistic regression analyses. RESULTS: Spermatogenesis was present in 70% (72/103) of the patients; it was widespread in 63% (45/72) and focal in 38% (27/72). Neither tumour type, stage, presence of microcalcification nor tumour markers predicted spermatogenesis. Men with a percentage testis tumour occupation (PTTO) of >50% of their testis were 82% (95% confidence interval 73.2-98.4) less likely to have spermatogenesis than a PTTO of <50%. CONCLUSIONS: Spermatogenesis is present in most testes affected by TGCTs; it is widespread in two-thirds of patients, and located away from the tumour in 94%. These findings can help predict and guide successful surgical sperm retrieval in testes with TGCTs. The finding of focal spermatogenesis in a third of patients would support a microsurgical approach to sperm retrieval at the time of orchidectomy to maximise success.

Deterministic Evolutionary Trajectories Influence Primary Tumor Growth: TRACERx Renal.

The evolutionary features of clear-cell renal cell carcinoma (ccRCC) have not been systematically studied to date. We analyzed 1,206 primary tumor regions from 101 patients recruited into the multi-center prospective study, TRACERx Renal. We observe up to 30 driver events per tumor and show that subclonal diversification is associated with known prognostic parameters. By resolving the patterns of driver event ordering, co-occurrence, and mutual exclusivity at clone level, we show the deterministic nature of clonal evolution. ccRCC can be grouped into seven evolutionary subtypes, ranging from tumors characterized by early fixation of multiple mutational and copy number drivers and rapid metastases to highly branched tumors with >10 subclonal drivers and extensive parallel evolution associated with attenuated progression. We identify genetic diversity and chromosomal complexity as determinants of patient outcome. Our insights reconcile the variable clinical behavior of ccRCC and suggest evolutionary potential as a biomarker for both intervention and surveillance.

Testicular microlithiasis in patients with testicular cancer in the United Kingdom and in Denmark.

INTRODUCTION: Testicular cancer is the most common type of cancer in young Caucasian men. It has been suggested that testicular microlithiasis (TML) is a premalignant condition. This study's objective was to investigate TML histology prevalence in testicular cancer patients in two European populations. METHODS: We analysed archived histopathology orchiectomy specimens from 152 patients diagnosed with testicular cancer at Fredericia Hospital in Denmark from 2004 to 2014, and 106 patients diagnosed at St Thomas' Hospital in London from 2011 to 2015. RESULTS: The Danish patients' median age was 37 years (range: 16-74 years) and the English patients' 36 years (range: 18-78 years). In the Danish patients, 29 (19.1%) had TML, and in the English patients, 43 (40.6%) had TML (p < 0.001). Haematoxylin bodies were slightly more common in the English patients. Laminated calcification was more often seen in seminomas than in non-seminomas.
 CONCLUSIONS: The English testicular cancer patients had a statistically significantly higher TML prevalence than the Danish patients. This observation questions the hypothesised biological association between TML and testicular cancer. FUNDING: The Region of Southern Denmark supported this study. TRIAL REGISTRATION: not relevant.

A Re-evaluation of Discarded Deceased Donor Kidneys in the UK: Are Usable Organs Still Being Discarded?

BACKGROUND: A significant proportion of procured deceased donor kidneys are subsequently discarded. The UK Kidney Fast-Track Scheme (KFTS) was introduced in 2012, enabling kidneys at risk of discard to be simultaneously offered to participating centers. We undertook an analysis of discarded kidneys to determine if unnecessary organ discard was still occurring since the KFTS was introduced. METHODS: Between April and June 2015, senior surgeons independently inspected 31 consecutive discarded kidneys from throughout the United Kingdom. All kidneys were biopsied. Organs were categorized as usable, possibly usable pending histology, or not usable for implantation. After histology reports were available, final assessments of usability were made. RESULTS: There were 19 donors (6 donations after brain death, 13 donations after circulatory death), with a median (range) donor age of 67 (29-83) years and Kidney Donor Profile Index of 93 (19-100). Reasons for discard were variable. Only 3 discarded kidneys had not entered the KFTS. After initial assessment postdiscard, 11 kidneys were assessed as usable, with 9 kidneys thought to be possibly usable. Consideration of histological data reduced the number of kidneys thought usable to 10 (10/31; 32%). CONCLUSIONS: The KFTS scheme is successfully identifying organs at high risk of discard, though potentially transplantable organs are still being discarded. Analyses of discarded organs are essential to identify barriers to organ utilization and develop strategies to reduce unnecessary discard.

A Multicenter Cohort Study of Histologic Findings and Long-Term Outcomes of Kidney Disease in Women Who Have Been Pregnant.

BACKGROUND AND OBJECTIVES: For many women pregnancy is the first contact with health services, thus providing an opportunity to identify renal disease. This study compares causes and long-term renal outcomes of biopsy-proven renal disease identified during pregnancy or within 1 year postpartum, with nonpregnant women. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Native renal biopsies (1997-2012), in women of childbearing age (16 to <50 years), from 21 hospitals were studied. The pregnancy-related diagnosis group included those women with abnormal urinalysis/raised creatinine identified during pregnancy or within 1 year postpartum. Pregnancy-related and control biopsies were matched for age and ethnicity (black versus nonblack). RESULTS: One hundred and seventy-three pregnancy-related biopsies (19 antenatal, 154 postpregnancy) were identified and matched with 1000 controls. FSGS was more common in pregnancy-related biopsies (32.4%) than controls (9.7%) (P<0.001) but there were no differences in Columbia classification. Women with a pregnancy-related diagnosis were younger (32.1 versus 34.2 years; P=0.004) and more likely to be black (26.0% versus 13.3%; P<0.001) than controls, although there were no differences in ethnicities in women with FSGS. The pregnancy-related group (excluding antenatal biopsies) was more likely to have a decline in Chronic Kidney Disease Epidemiology Collaboration eGFR in the follow-up period than the control group (odds ratio, 1.67; 95% confidence interval, 1.03 to 2.71; P=0.04), and this decline appeared to be more rapid (-1.33 versus -0.56 ml/min per 1.73 m2 per year, respectively; P=0.045). However, there were no differences between groups in those who required RRT or who died. CONCLUSIONS: Pregnancy is an opportunity to detect kidney disease. FSGS is more common in women who have been pregnant than in controls, and disease identified in pregnancy or within 1 year postpartum is more likely to show a subsequent decline in renal function. Further work is required to determine whether pregnancy initiates, exacerbates, or reveals renal disease.

[18F]-Fluorodeoxyglucose Positron Emission Tomography in the Diagnosis, Treatment Stratification, and Monitoring of Patients with Retroperitoneal Fibrosis: A Prospective Clinical Study.

BACKGROUND: The ability to distinguish malignant from benign retroperitoneal fibrosis (RPF) and to select patients who are likely to respond to steroid treatment using a noninvasive test would be a major step forward in the management of patients with RPF. OBJECTIVE: To prospectively evaluate the potential of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) to improve clinical decision-making and management of RPF. DESIGN, SETTING, AND PARTICIPANTS: A total of 122 RPF patients were assessed and managed by a multidisciplinary RPF service between January 2012 and December 2015. Of these, 78 patients underwent 101 FDG-PET scans, as well as computed tomography and blood tests. Management was based on the findings from these investigations. Median follow-up was 16 mo. RESULTS AND LIMITATIONS: Of the 24 patients with negative [18F]-FDG-PET, none (0%) had malignancy on biopsy (negative predictive value 100%). [18F]-FDG-PET identified malignancy in 4/4 patients (100%) before biopsy. All four patients had highly avid PET (maximum standardised uptake value ≥4) with atypical avidity distribution. [18F]-FDG-PET revealed avidity in 19/38 patients (50%) with normal inflammatory markers and no avidity in 10/63 patients (16%) with raised marker levels. Patients with highly avid PET were significantly more likely to respond to steroids compared to those with low avidity (9/11 [82%] vs 3/24 [12%]; p<0.01) or negative PET (9/11 [82%] vs 0/14 [0%]; p<0.01). Limitations include the small number of patients and the predominance of tertiary referrals, which may represent patients with particularly problematic RPF. CONCLUSIONS: This study has established a promising role for [18F]-FDG-PET in optimising and individualising the treatment of RPF. PATIENT SUMMARY: This study shows that [18F]-fluorodeoxyglucose positron emission tomography scans could reduce the need for biopsy in patients with retroperitoneal fibrosis (RPF). This technique can distinguish cancer from noncancerous RPF, and may be better than blood tests in assessing and monitoring RPF. It also appears to predict a patient's response to steroids, which should allow more individualised treatment.