The Banff Schema for Allograft Pathology: Revisiting Scoring Paradigms for Inflammation and Tubulitis
Lin Liu, Parmjeet Randhawa. University of Pittsburgh, Pittsburgh
Background: Diagnostic categories in the Banff Schema are based on evaluation of non-scarred areas for inflammation (Banff-i) and tubulitis(Banff-t). We investigated how diagnostic algorithms might be affected by (a) presence of severe inflammation which can mask tubular disruption and lead to under-grading of tubulitis (Banff-t), and (b) replacement of Banff-i by a total inflammatory score (ti) encompassing both scarred and non-scarred areas.
Design: To study potential under-grading of tubulitis, ∼2000 biopsies were retrieved for review and 14 cases scored as i3t1v0 were rescored for Banff-i, ti, Banff-t, and t-total (defined as peak tubulitis in scarred or unscarred cortex). Tubulitis was not scored in areas with greater than mild atrophy recognized by (a) tubular basement membrane thickening or (b) >50% decrease in tubule diameter.
Results: 12 of 14 retrieved cases showed tubular disruption, which led to upgrading of tubulitis from t1 to t3. The remaining 2 cases showed tubulitis only in tubules with significant atrophy and were not further considered.
Biopsy review using conventional Banff criteria altered the diagnosis from 'Borderline change' to T-cell mediated rejection (TCMR)-Type 1B in 3 cases, one of which was C4d positive. Two (2) cases with ti=3, Banff i<3, and tubular disruption were found. Given recent evidence that ti correlates well with intra-graft molecular disturbances (AJT 2009:9:1859), it is proposed that the latter biopsies also be classified as TCMR-Type 1B. In 6 biopsies (3 in the Banff-i=3 group, 3 in the Banff-i<3,ti=3 group), interpretation of TCMR–like changes was confounded by concurrent findings suspicious for infection (neutrophilic tubulitis, intra-tubular neutrophil clusters), and another biopsy (Banff-i=3 group) showed κ-light chain restricted plasma cells.
Conclusions: Biopsies where an initial evaluation suggests a score of i3t1 should be evaluated for antibody mediated rejection and urinary tract infection. The presence of tubular disruption should be sought as this may lead to an upgrading of TCMR. Some biopsies show tubular disruption with a ti=3 but Banff-i score of 1 or 2: given recent evidence that ti is superior to Banff-i in predicting graft dysfunction, we propose that these biopsies also be considered TCMR-type 1B, pending validation by future studies.
Category: Kidney (does not include tumors)
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 290, Wednesday Afternoon