Key Points of the Banff 2019 Classification of Renal Allograft Pathology

Area of Science:

• Nephrology
• Transplant Pathology
• Immunology

Background:

• The Banff classification is the global standard for diagnosing renal allograft pathology.
• The 15th Banff Conference in 2019 introduced updated classification criteria.
• Accurate diagnosis of renal transplant rejection is critical for patient outcomes.

Purpose of the Study:

• To summarize key changes in the Banff 2019 classification for renal allograft pathology.
• To highlight significant updates impacting the diagnosis of kidney transplant rejection.
• To identify ongoing issues and areas needing clarification within the Banff 2019 criteria.

Main Methods:

• Mini-review of the Banff 2019 Kidney Meeting Report.
• Analysis of changes introduced in the Banff 2019 classification.
• Identification of specific criteria revisions and new additions.

Main Results:

• Reversion of borderline change criteria to ≥ i1.
• Incorporation of the t-IFTA score into the classification.
• Adoption of histological classification for polyoma virus nephropathy.
• Addition of a category for chronic (inactive) antibody-mediated rejection.
• Requirement to note diffuse or focal spread in peritubular capillaritis.
• Continued ambiguity in the definition of the 't score' for tubulitis.

Conclusions:

• The Banff 2019 classification introduces significant refinements for diagnosing renal transplant rejection.
• Updates aim to enhance diagnostic precision and cover a broader range of pathological findings.
• Clarification of the 't score' definition is needed to resolve contradictions and improve consistency.