Kidney summary from 12th Banff Conference on Transplant Pathology from the meeting in Comandatuba-Bahia, Brazil on August 23rd, 2013 http://cybernephrology.ualberta.ca/banff/2013

1. Summary and Closing Remarks - Kidney
Mark Haas
Cedars-Sinai Medical Center
Los Angeles, California, USA

2. 4 years after the initiation of
the Banff working groups,
their efforts are coming to
fruition!

3. Isolated vasculitis responds to anti-rejection treatment
* p<0.05, compared to group 3
*
*
*
*
Slide courtesy of Banu Sis

4. Death-censored Graft survival is worse in isolated vasculitis than
in no rejection and comparable to Banff II rejections
Isolated v (N=100, F=21)
V + T-I rejection (N=98, F=21)
No V and T-I rejection (N=99, F=9)
p=0.028
N= 297
F=51
Median F/U time: 39.1 months
Post biopsy time (days)
Cumulativesurvival
Slide Courtesy of Banu Sis

5. Proposal for standard definition and scoring system of
Glomerulitis and Glomerular Double Contours
• Glomerulitis is defined as intra-capillary loop mononuclear inflammatory cell infiltration AND
endothelial cell enlargement with occlusion or near-occlusion of 1 or more capillary lumens.
The extent of glomerulitis is scored based on percentage using PAS and/or silver sections
(w/wo CD68) as follows;
• g0 - no glomerulitis (0%)
• g1 - segmental or global glomerulitis in 1-25% of glomeruli
• g2 - segmental or global glomerulitis in 25-75% of glomeruli
• g3 - segmental or global glomerulitis in >75% of glomeruli
Transplant glomerulopathy is defined as presence of glomerular peripheral capillary loop
duplications observed using PAS and/or silver stained sections and absence of significant IC
deposits along capillary walls by IF and/or EM studies.
Double contours scored as follows;
• cg0 – NO double contours of the GBM (0%) in any glomeruli using LM PAS/silver or EM.
• cg1 – double contours of the GBM in 1-25% of capillaries in the most involved glomerulus by
LM. If there is less than 10% of capillaries with double contours, confirmation by EM with
demonstration of few double contours PLUS endothelial activation is needed.
• cg2 – double contours of the GBM in 26-50% of capillaries in the most involved glomerulus
• cg3 – double contours of the GBM in >50% of capillaries in the most involved glomerulus
Slide courtesy of Banu Sis

6. Implantation Biopsy Working Group-Helen Liapis
1. Wedge biopsy adequate; frozen wedge biopsy actually
shows less inter-observer variability than frozen core biopsy for
evaluation of several parameters (globally sclerotic glomeruli, arterial
intimal fibrosis) – what constitutes an adequate wedge?
2. Inter-observer agreement for evaluation of most parameters is better
on paraffin sections than on frozen sections, however for wedge
biopsy the difference is modest
3. Inter-observer agreement is excellent to good for assessing
glomerular parameters; fair to good for vascular and interstitial
parameters
4. Digital evaluation of these biopsies works well
5. No correlation between histologic parameters and DGF, SCr at 6 and
12 months. However, sample size small and all biopsies had <20%
globally sclerotic glomeruli. Additional studies needed in a larger and
possibly more histologically variable set of biopsies.

7. Polyoma Working Group – Volker Nickeleit
Recommended Scoring System
PVN 1 - PV inclusions by LM and IHC <1% (pvl 1); ci 0-1
PVN 2 - pvl 1 and ci 2-3
pvl 2 (1 – 10% inclusions); ci 0-3
pvl 3 (>10% inclusions); ci 0-1
PVN 3 – pvl 3 and ci 2-3
No rejection before bx/during F/U
PVN peak SCr incr from peak, 12mo graft loss by 24mo
1 1.7 0.2 12%
2 2.1 0.4 19%
3 2.6 1.2 50%
p = 0.023

8. Full-blown acute AMR (acute AMR type 1); all 4 features must be present for
diagnosis
•Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)
•Histologic evidence, including one or more of the following:
Microvascular injury (g > 0* and/or ptc >0)
Intimal or transmural arteritis (v >1)**
Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)
Acute tubular injury, in the absence of any other apparent cause for this
•Immunohistologic evidence, including one or more of the following:
Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections,
C4d >0 by IHC on paraffin sections)
IgG and/or complement deposition in arteries (excluding arteries with hyalinization)
•Evidence of acute graft dysfunction, including an acute rise in serum creatinine or
new onset of proteinuria, if no evidence or recurrent or de novo glomerular disease
*Recurrent/de novo glomerulonephritis should be excluded
**These arterial lesions may be indicative of AMR, CMR, or frequently mixed
AMR/CMR. “v” lesions and immunofluorescence are not scored in arterioles.

9. Acute AMR without Evident Complement Deposition (acute AMR type 2); all 4
features must be present for diagnosis
- Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)
- Histologic evidence, including one or more of the following:
Microvascular injury (g > 0* AND ptc >0)
Intimal or transmural arteritis (v >1)**
Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)
Acute tubular injury, in the absence of any other apparent cause for this
- No evidence of complement deposition
C4d staining in <10% of peritubular capillaries (C4d0 or C4d1) by IF on frozen
sections, no C4d staining (C4d = 0) by IHC on paraffin sections
No IgG and/or complement deposition in arteries (does not include arteries with
hyalinization)
- Evidence of acute graft dysfunction, including one or more of the following:
Acute rise in serum creatinine
New onset of proteinuria, if no evidence or recurrent or de novo glomerular disease
*Recurrent/de novo glomerulonephritis should be excluded

10. C4d-positive subclinical AMR (subclinical AMR type 1); all 4 features must
be present for diagnosis
•Serologic evidence (donor-specific anti-HLA or other donor-specific
antibodies)
•Histologic evidence, including one or more of the following:
Microvascular injury (g > 0* and/or ptc >0)
Intimal or transmural arteritis (v >1)**
Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)
•Immunohistologic evidence, including one or more of the following:
Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen
sections, C4d >0 by IHC on paraffin sections
•Stable serum creatinine, no new onset of proteinuria
*Recurrent/de novo glomerulonephritis should be excluded
**It should be noted that these arterial lesions may be indicative of AMR, CMR,
or frequently mixed AMR/CMR. “v” lesions and immunofluorescence are not
scored in arterioles.

11. Subclinical AMR without Evident Complement Deposition (subclinical
AMR type 2); all 4 features must be present for diagnosis
•Serologic evidence (donor-specific anti-HLA or other donor-specific
antibodies)
•Histologic evidence, including one or more of the following:
Microvascular injury (g > 0* and/or ptc >0)
Intimal or transmural arteritis (v >1)**
Thrombotic microangiopathy (if no other apparent cause, e.g. recurrent HUS)
-No evidence of complement deposition
C4d staining in <10% of peritubular capillaries (C4d0 or C4d1) by IF on
frozen sections, no C4d staining (C4d = 0) by IHC on paraffin sections
•Stable serum creatinine, no new onset of proteinuria
*Recurrent/de novo glomerulonephritis should be excluded
**It should be noted that these arterial lesions may be indicative of AMR, CMR,
or frequently mixed AMR/CMR. “v” lesions and immunofluorescence are not
scored in arterioles.

12. C4d-positive chronic AMR (chronic AMR type 1); all 3 features must be
present for diagnosis
- Serologic evidence (donor-specific anti-HLA or other donor-specific antibodies)
- Morphologic evidence, including one or more of the following:
Transplant glomerulopathy (cg >1), if no clinical evidence of chronic TMA
Peritubular capillary basement membrane multilayering (requires EM)
Arterial intimal fibrosis of new onset
- Immunohistologic evidence, including one or more of the following:
Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen
sections, C4d >0 by IHC on paraffin sections)

13. Chronic AMR without Evident Complement Deposition (chronic AMR type
2); all 3 features must be present for diagnosis
- Serologic evidence (donor-specific anti-HLA or other donor-specific
antibodies)
- Morphologic evidence, including one or more of the following:
Transplant glomerulopathy (cg >1), if no clinical evidence of chronic TMA
Peritubular capillary basement membrane multilayering (requires EM)
Arterial intimal fibrosis of new onset
- Immunohistologic evidence, including one or more of the following:
Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen
sections, C4d >0 by IHC on paraffin sections
If a biopsy shows histologic evidence for acute AMR and also meets above
criteria for chronic AMR, the term “chronic active AMR” (C4d-positive or
without evident complement deposition) may be appropriately used.

14. C4d Staining Without Histologic Evidence of Rejection; all 3 features must be
present for diagnosis
•Linear C4d staining in peritubular capillaries (C4d2 or C4d3 by IF on frozen sections,
C4d>0 by IHC on paraffin sections)
•g = 0, ptc = 0, cg = 0 (by light microscopy and EM), v = 0; no TMA, no peritubular
capillary basement membrane multilayering, no acute tubular injury (in the absence of
another apparent cause for this)
•No acute cell-mediated rejection (Banff 97 type 1A or greater)

15. Comments on Proposed AMR Classification
21 total responses – could not open 1
MVI Threshold
OK as is – 2
Any g or ptc – 1
Too low for C4d-negative cases – 5
suggest (g + ptc >3) - 2
(g + ptc + v) >3 – 1
v1, v2, v3 as histological evidence for AMR – 6/6
(one suggested IHC typing of intimal cells)
C4d1 by IF
Consider as negative – 4
Negative should be completely negative (C4d0) - 1
More data needed - 1

16. Terminology
Favor AMR without evident complement deposition – 6
Favor C4d-negative AMR – 4
Favor complement–negative AMR - 1

17. Consider EM findings in cg scoring
Yes, as cg1 if double contours present – 10
Yes, as cg1 if GBM duplication in >3 capillaries - 1
Yes, but need more specific criteria – 3
Consider ptc serrations in addition to glomerular changes – 1
No need to separate clinical from subclinical AMR – 4
Eliminate new onset proteinuria as clinical criterion for acute
AMR – 4
Eliminate Arterial Ig/Complement Deposition as
immunohistologic criterion for acute AMR – 4
Change smoldering to subclinical - 7
Eliminate the term “Accommodation” - 3

18. Some additional comments (n = 1)
- Clarify if ptc>0 includes both focal and diffuse; consider WG
evaluation of ptc scoring similar to that done for g, cg
- C4d+ chronic AMR should be considered chronic/active
- Include IF/TA as histologic criterion for chronic AMR
- Include post-transplant increase in cv score by >1 as
histologic criterion for chronic AMR
- C4d-negative clinical acute AMR is very rare
- Add comment that C4d is not reliable diagnostic tool in ABOi
- Make it shorter

19. What to do with MVI in absence of C4d and DSA
Merits comment, not diagnosis (6/6)
Test for non-HLA DSA (3)
Consider molecular testing
Consider follow-up biopsy

20. Based on the scientific
sessions and the three
discussion sessions, 3 new
renal Banff working groups
are being proposed.

21. Proposed Working Group for CMR
Questions to address:
1. Should ti be included in classification for CMR diagnosis?
- As a replacement for the i score
- As part of a new category of chronic/active CMR
- Include in diagnosis line but not within classification
per se
- Include as a comment, not necessarily in diagnosis line
- Other suggestions

22. Proposed Working Group for CMR
Questions to address:
2. Should the borderline category be modified to try and
identify those lesions most specific for active CMR?
- By assessing edema and tubular injury (as in CCTT)
- By including immunohistochemical stains (e.g.,
granzyme B)
- By assessing the extent of tubulitis (as in CCTT)
- By inclusion of molecular data where available, and if
so what are the most useful transcripts/transcript sets
to examine?
3.Are there clinical and pathologic differences in
borderline infiltrates in for cause vs. protocol biopsies?

23. A new working group comprised of clinicians,
pathologists, and clinical immunologists to:
1. Develop evidence-based recommendations for
transplantation of patients with broad sensitization
and high titer DSAs, for whom the only transplant
option is desensitization?
- How frequently to monitor DSA
- Role of protocol biopsies, when (and to how far out
post-transplant) should this be done
- Should an increase in DSA without a change in graft
function prompt a biopsy?
- What are the minimal capabilities a center needs to
have to support care for these patients (including
but not limited to HLA lab/pathology evalation and
TAT, available therapies, specialized personnel)

24. A new working group comprised of clinicians, clinical
immunologists, and pathologists to:
2. Systematically evaluate possible differences in AMR
(clinically, serologically, pathologically, and from a
molecular standpoint) in this group of patients versus
those of other sensitized patients and of non-
sensitized patients with de novo DSA that may be
relevant to how the patients are treated?

25. Working Group for Evaluation of Non-Morphologic
Data in Renal Allografts
1. Develop consensus guidelines for:
- Circumstances under which it is advisable to
perform serologic testing for DSAs and molecular
analysis on renal biopsy tissue and/or
serum/urine collected at the time of biopsy.
- What are the best molecular studies to perform
under specific circumstances (e.g., early and late
C4d-negative AMR)
2. Find applicable molecular markers that are associated
with improved prediction of clinical outcomes and/or
improved inter-observer variability of biopsy
interpretation, and can be tested for at different centers
with acceptable inter-center agreement

26. EM is clearly useful as a predictive tool for development of
TG, and may help guide additional testing (e.g., for DSA)
and therapeutic approach to patients with early
ultrastructural capillary lesions
2 proposals:
1.Divide the cg1 category into:
cg1a – GBM double contours (new lamina densa) and
subendothelial widening (LRI expansion) by EM; no GBM
double contours by light microscopy
cg1b – GBM double contours in at least one glomerulus by
light microscopy; confirmation by EM recommended

27. 2. Make recommendation that tissue be taken for EM
from renal allograft biopsies:
- If any clinical suspicion of recurrent or de novo
glomerular disease
- If any significant proteinuria
- If specific risk factors for TG:
Pre-sensitized patients with positive crossmatch
History of DSA+, preformed or de novo
History of C4d+ or microvascular inflammation
(g,ptc) in a previous biopsy
- All grafts > 3 months (or 6 months?) post-tx;
looking
for ultrastructural features of early TG & PTCBMML
and/or changes predictive of development of TG
From Ian Gibson

28. Obrigado (thank you) to everyone
who sent me their comments on the
proposed AMR classification, and
especially to our hosts Daisa, Elias,
and Cristina!