The diffuse extent of peritubular capillaritis in renal allograft rejection is an independent risk factor for graft...

Area of Science:

• Nephrology
• Transplant Pathology
• Immunology

Background:

• The Banff classification mandates reporting peritubular capillaritis (PTC) score, extent, and cellularity in renal allograft pathology.
• While PTC score is a known prognostic factor, the clinical significance of its extent and cellular composition remains unclear.

Purpose of the Study:

• To investigate the prognostic value of PTC score, extent, and cellular composition in predicting renal allograft loss.
• To determine if detailed reporting of inflammatory cell types in PTC provides additional prognostic information.

Main Methods:

• Retrospective analysis of 1322 indication biopsies from 749 renal transplant recipients.
• Evaluation of PTC prevalence, score (1-3), extent (focal/diffuse), and cellular composition (mononuclear, granulocytic, mixed).
• Statistical analysis to identify risk factors for allograft loss and eGFR decline.

Main Results:

• Prevalence of PTC scores 1, 2, and 3 was 10.7%, 11.6%, and 2.6%, respectively.
• Diffuse PTC occurred in 14.4% of cases and was associated with higher allograft loss rates (HR 1.67).
• PTC score of 3 (HR 2.57) and diffuse PTC were significant risk factors for allograft loss and independently associated with chronic antibody-mediated rejection and eGFR decline. Cellular composition provided no additional prognostic value.

Conclusions:

• The score and extent (specifically diffuse) of peritubular capillaritis are essential for assessing kidney transplant prognosis.
• Detailed reporting of inflammatory cell types in PTC does not confer additional prognostic information beyond score and extent.
• Focusing on PTC score and extent aids in better risk stratification for renal allograft loss.