A 2018 Reference Guide to the Banff Classification

1 Downloadedfrom BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4 XMi0hCywCX1 AWnYQp/IlQrHD3lO0fy3 QXco/NzXmRwEGbz2bgRcGow+0v+DcHdF89 ZuGUwKj2xQoUHQ==on 01/18/2019 Downloadedfrom BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4 XMi0hCywCX1 AWnYQp/IlQrHD3lO0fy3 QXco/NzXmRwEGbz2bgRcGow+0v+DcHdF89 ZuGUwKj2xQoUHQ==on 01/18/2019A 2018 Reference Guide to the Banff Classificationof Renal Allograft PathologyCandice Roufosse, MD, PhD,1,2 Naomi Simmonds, MD,3 Marian Clahsen-van Groningen, MD, PhD,4 Mark Haas, MD, PhD,5 Kammi J. Henriksen, MD,6 Catherine Horsfield, MD,3 Alexandre Loupy, MD,7 Michael Mengel, MD,8 Agnieszka Perkowska-Ptasi ska, MD,9 Marion Rabant, MD, PhD,10 Lorraine C.

2 Racusen, MD,11 KimSolez,MD,8and Jan U. Becker, MD12 Abstract:The Banff Classification of Allograft Pathology is an international consensus Classification for the reporting of biopsiesfrom solid organ transplants. Since its initial conception in 1991 for renal transplants, it has undergone review every 2 years, withattendant updated publications. The rapid expansion of knowledge in the field has led to numerous revisions of the resultant dispersal of relevant content makes it difficult for novices and experienced pathologists to faithfully apply the classi-fication in routine diagnostic work and in clinical trials. This review shall provide a complete and simple illustrated Reference Guide ofthe Banff Classification of Kidney Allograft Pathology based on all publications including the 2017 update.

3 It is intended as a con-cise desktop Reference for pathologists and clinicians, providing definitions, Banff Lesion Scores and Banff Diagnostic online website Reference Guide hosted by the Banff Foundation for Allograft Pathology ( ) is being de-veloped, which will be updated with future refinement of the Banff Classification from 2019 onward.(Transplantation2018;102: 1795 1814)Since its first consensus meeting in 1991,1the Banff Clas-sification of Allograft Pathology has provided a frame-work for the reporting of renal allograft biopsies. It was thefirst Classification system of its kind and answered the needfor an international consensus on renal transplant biopsyreporting, providing guidance for clinical diagnosis and en-abling meaningful comparison between research studiesand clinical trials investigating the diagnosis, treatment andoutcome in kidney transplantation.

4 The Banff Classificationhas since been further strengthened by evidence-informed bi-annual updates elaborated during open international a result, the Banff Classification of AllograftPathology has become the predominant Classification systemused total of 14 meetings reported in 10 articles reflect the de-velopments of the Banff Classification from the first consen-sus meeting in 1991 to the recently published consensusReceived 19 February 2018. Revision received 7 May 23 May of Medicine, Imperial College, London, United West London Pathology, London, United of Histopathology, Guy's and St. Thomas' National Health ServiceFoundation Trust, London, United of Pathology, Erasmus MC, Rotterdam, The of Pathology, Cedars-Sinai Medical Center, Los Angeles, of Pathology, University of Chicago, Chicago, Translational Research Center for Organ Transplantation, Paris, of LaboratoryMedicine and Pathology, University of Alberta,Edmonton, of Transplantology, Nephrology and Internal Diseases, Medical Uni-versity of Warsaw, Warsaw, of Pathology, Necker Hospital University Paris Descartes, Paris, Johns Hopkins University, Baltimore, of Pathology, University Hospital of Cologne, Cologne.

5 's and 's contribution to this research is supported by the National Institutefor Health Research (NIHR) Biomedical Research Centre based at Imperial CollegeHealthcare NHS Trust and Imperial College London. is supported by aresearch grant ATIP AVENIR from the National French Institute of Research. issupported by the European Rare Kidney Disease Network (ERKNet) and by theDeutsche Forschungsgemeinschaft (DFG, German Research Foundation - BE-3801).The authors declare no conflicts of authors contributed the discussion of the content, the collation of images andillustrations and to writing of the : Jan U. Becker, MD, Institute of Pathology, University Hospital ofCologne, Kerpener Str.

6 62, 50937, Germany. digital content (SDC) is available for this article. Direct URL citationsappear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal s Web site ( ).Copyright 2018 The Author(s). Published by Wolters Kluwer Health, Inc. This is anopen access article distributed under the Creative Commons Attribution License (CCBY), which permits unrestricted use, distribution, and reproduction in any me-dium, provided the original work is properly : 0041-1337/18/10211-1795 DOI: November 2018 Volume 102 Number the 2017 meeting in Barcelona, ,4-12 Each of theseiterations provides a short summary of the meeting and con-tributes to the Classification in a cumulative fashion.

7 The dis-persal of both relevant and outdated content over 10 articlescould make access to the Banff Classification difficult for be-ginners and experts and has created ambiguities in the , accessibility and clarity are of utmost importance not onlyfor clinical practice and research but also for the Banff Classi-fication itself to evolve through accountability, critique, andchange. To improve on these aspects, the Rules and Dissemi-nation Banff Working Group was initiated at the last Banffmeeting held in Barcelona, Spain in March 2017. With a scopebeyond the helpful syllabus provided by the Banff group in theonline supplement of the 2015 update11and incorporating thelatest changes introduced in the 2017 update,12the aim of thisWorking Group is to collate all current content of the BanffClassification and improve its accessibility.

8 A systematic inven-tory of the content is given in Figure 1. This practical Guide isbased on all content up to the 2017 update as the first outputof our Working Group. It is divided in the following sections: abrief Guide about the histopathological and serological work-up; a list of Banff Lesion Scores (previously known as compo-nents, eg, Banfftfor tubulitis) with their current definitions,practical tips for their application and illustrative figures(see definitions below and thresholds in Table 2); and a listof Banff Diagnostic Categories in Table 1. Moreover, we pro-vide a list of Additional Diagnostic Parameters, which needto be considered in addition to Banff Lesion Scores to reacha Banff Diagnostic Category (Table 3).

9 Examples for theseinclude Severe Peritubular Capillary Basement MembraneMultilayering which is among the criteria for antibody-mediated rejection (AMR) provided as Supplemental Digital Content (seeGlossaryof Terms, SDC, ), explainingimportant concepts and terminology underlying the BanffClassification. Lastly, we provide a critical appraisal of areasof the Banff Classification that require clarification andprovide an outlook for future developments. All terms fromthe Banff Classification will be given in capitals for clarity,all abbreviations for Banff lesion scores will be given initalic hope this Banff 101 will serve as a handy Reference forthe clinicians and the pathologists, until the entire updatedcontent appears online with the 2019 update of the Banff Clas-sification of Renal Allograft Pathology, replacing this WORK-UP OF BIOPSIESA kidney transplant biopsy should fulfill the criteria forspecimen adequacy (seeGlossary of Terms, SDC, ) detailed in the Banff 1997 staining is considered indispensable, either as immuno-fluorescence (IF) on fresh frozen or immunohistochemistry(IHC)

10 On paraffin-embedded tissue. The paraffin block shouldbe cut in several numbered level sections examined withhematoxylin-eosin, periodic acid-Schiff (PAS), trichrome-elastic and Jones or methenamine silver stains. Immunohisto-chemistry staining for simian virus-40, cross-reacting withBK virus is highly recommended when indicated. Where avail-able, minute portions of cortex should be embedded for trans-mission electron microscopy (EM).Depending on clinical and histopathological findingsa complete nephropathological work-up including stainingfor immunoglobulin heavy and light chains and complementsplit products might be necessary to rule out or confirm a di-agnosis of glomerulonephritis.