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Abstract: SA-PO1056

Prospective Assessment of the Need, Discrepancies, and Added Value of Molecular Diagnostics of Kidney Allograft Biopsies: An Evaluation in Clinical Practice

Session Information

Category: Transplantation

  • 2102 Transplantation: Clinical


  • Schachtner, Thomas, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Von Moos, Seraina C., UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • López, Kai Castrezana, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Weidmann, Lukas, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Harmacek, Dusan, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Bortel, Nicola, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Korach, Raphael, UniversitatsSpital Zurich, Zurich, Zürich, Switzerland
  • Mueller, Thomas F., UniversitatsSpital Zurich, Zurich, Zürich, Switzerland

The Molecular Microscope Diagnostic System (MMDx) may resolve inconclusive histology findings, as preserved biopsy material can be examined after histology findings have been obtained. The extent to which this proposed approach can be implemented in clinical practice remains an open question.


We prospectively analyzed 102 consecutive indication kidney allograft biopsies by histology and MMDx at the University Hospital Zurich from April to September 2022. Pathologists and clinicians with experience in MMDx assessed the need for MMDx by questionnaire when the histology report was available. Clinicians then assessed the discrepancy rate and assumed added value by questionnaire when the MMDx report was available.


The need for MMDx was most frequently assessed for suspected ABMR (12/20) and mixed ABMR/TCMR (9/18) but less frequently for proven ABMR (1/11), TCMR/borderline (1/6), DSA only (1/20), and no ABMR/TCMR (3/28). Discrepancies were observed most frequently in cases with proven/suspected rejection (36/55) but rarely in the absence of histologic rejection (1/47). Clinicians considered an added value of molecular diagnostics mostly in suspected ABMR (3/20), mixed ABMR/TCMR (7/18), and TCMR/borderline (3/6). Classification into molecular ABMR occurred in 9 of 32 cases with suspected ABMR. However, classification into molecular TCMR was not observed in any of the 17 cases with suspected TCMR.


The need for MMDx in clinical practice goes beyond the recommendation for suspected ABMR. While discrepancies appear to be limited to cases with histologic rejection, an added value of MMDx is particularly suspected along the ABMR continuum. Because MMDx aims to overcome the inter-observer variability of histology, the potential added value of MMDx must be determined for each center individually.


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