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Abstract: SU-OR46

Minimum Diagnostic Criteria for Thrombotic Microangiopathy in Renal Allograft: The Banff TMA Working Group Phase I Results

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical


  • Afrouzian, Marjan, University of Texas Medical Branch at Galveston, Galveston, Texas, United States

Group or Team Name

  • Banff TMA Working Group

Thrombotic Microangiopathy (TMA) TMA is a serious complication of renal transplantation, usually with poor outcome. The Banff TMA Working Group (TMA-WG) was formed to study renal transplant TMA (t-TMA) aiming to: 1- Survey current practices used in the diagnosis of t-TMA; 2- Define minimum diagnostic criteria (MDC); and 3- Develop recommendations for accurate diagnosis integrating morphological, clinical, laboratory and molecular findings, where available. The project started with Phase I (pathology phase) and is continuing in Phase II (Nephrology phase).


Using the Delphi methodology during phase I, 23 nephropthologists who had >3 years of experience with t-TMA were asked to list their MDC for t-TMA in the following categories: 1- Light, 2- immunofluorescence, and 3- electron microscopy, 4- clinical history, 5- laboratory findings, 6- genetic testing and 7- raised differential diagnoses. Nine rounds (R) of surveys were designed. At the end of each R, MDC were narrowed down following Delphi rules. R6 and R7 were designated as the validation Rs in which the narrowed criteria were validated on 37 renal biopsies (25 TMA and 12 non-TMA cases) using Aperio Imagescope and whole slide digital images scanned @ X400. For each biopsy, pertinent pathology/history/laboratory/genetic information were provided. Descriptive statistical analysis was performed using SPSS program.


Starting with 338 criteria in R1 and following analysis of total 82,677 data entries, MDC were narrowed down to 35, by the end of R9. The graph illustrates the evolution of the criteria over 9 R. A complete list of 35 MDC will be presented at the meeting.


Applying the Delphi methodology to a cohort of t-TMA biopsies in Phase I of the project, nephropathologists from 4 continents generated histopathologic, clinical and laboratory MDC for renal t-TMA. Phase II (Nephrology consensus) and Phase III (consensus of the consensus groups- Combined Phases I & II) will follow Phase I to generate final MDC for t-TMA.


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