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Allograft renal biopsy remains the gold standard for diagnosing many conditions in the transplant recipient including rejections, infections, recurrent, and de-novo renal disease. The Banff schema of reporting is followed worldwide in arriving at the right diagnosis. The guidelines, the categories, and the Banff scores in this schema are constantly evolving and this has made the interpretation of the biopsy seem complex and difficult especially for the novice. In this review, a detailed description of the various patterns of injury specific to the graft, the Banff categories of diagnoses, the lesions, and the Banff scores are simplified and explained. Lastly, a systematic approach to these allograft biopsies, which can be followed in regular practice, and by which a tentative diagnosis can be made in most cases is laid out.

Pancreas transplantation is an effective therapy for diabetic patients, which can significantly improve the survival rate and quality of life of diabetic patients. According to the international registration of pancreas transplantation center, the global total pancreas transplantation has reached more than 80,000 cases by 2017, including pure pancreas transplantation and simultaneous pancreas-kidney transplantation (SPK). With the development and application of a new type of immunosuppressant, with the gradual maturity of organ preservation technology and surgical technology, the pancreas transplantation has rapidly on a global scale. However, pancreas transplantation still has more problems than limit its development compared with other organ transplantation. For example, the early diagnosis and treatment of pancreatic rejection are of considerable significance to the prognosis of pancreas transplantation. Some surveillance methods of diagnosis have been used increasingly, among which the histopathological diagnosis is particularly important. The first Banff schema for the histological diagnosis of pancreas rejection has been published, which primarily dealt with the diagnosis of acute T-cell-mediated rejection (ACMR). In recent years, antibody-mediated rejection (AMR) has been more emphasized as the primary cause of graft failure. The Banff pancreas allograft rejection grading schema was updated in 2011 by a broad-based multidisciplinary panel, presenting comprehensive guidelines for the diagnosis of AMR.

The Banff Working Group on Liver Allograft Pathology reviewed and discussed literature evidence regarding antibody-mediated liver allograft rejection at the 11th (Paris, France, June 5-10, 2011), 12th (Comandatuba, Brazil, August 19-23, 2013), and 13th (Vancouver, British Columbia, Canada, October 5-10, 2015) meetings of the Banff Conference on Allograft Pathology. Discussion continued online. The primary goal was to introduce guidelines and consensus criteria for the diagnosis of liver allograft antibody-mediated rejection and provide a comprehensive update of all Banff Schema recommendations. Included are new recommendations for complement component 4d tissue staining and interpretation, staging liver allograft fibrosis, and findings related to immunosuppression minimization. In an effort to create a single reference document, previous unchanged criteria are also included.

The aim of this study was to determine how the Banff antibody-mediated rejection (ABMR) classification for kidney transplantation is interpreted in practice and impacts therapy. The Banff Antibody-Mediated Injury Workgroup electronically surveyed clinicians and pathologists worldwide regarding diagnosis and treatment for six case-based scenarios. The participants’ (95 clinicians and 72 renal pathologists) assigned diagnoses were compared to the Banff intended diagnoses (reference standard). The assigned diagnoses and reference standard differed by 26.1% (SD 28.1%) for pathologists and 34.5%(SD 23.3%) for clinicians. The greatest discordance between the reference standard and clinicians’ diagnosis was when histologic features of ABMR were present but donor-specific antibody was undetected [49.4%(43/87)]. For pathologists, the greatest discordance was in the case of acute/active ABMR C4d staining negative in a positive crossmatch transplant recipient[33.8%(23/68)]. Treatment approaches were heterogeneous, but linked to the assigned diagnosis. When acute/active ABMR was diagnosed by the clinician, treatment was recommended 95.3%(SD 18.4%) of the time versus only 77.7%(SD 39.2%) of the time when chronic active ABMR was diagnosed (P

The Banff schema is the most widely used standard grading system for liver allograft rejection. To investigate the relationship between the Banff rejection activity index (RAI) and the presence of lymphocyte subpopulations in allograft liver tissue, assuming these cells to probably play an important role in the mechanism of acute cellular rejection (ACR), we performed immunohistological examinations using liver tissues with various ACR severities after living related liver transplantation (LRLT). In total, 37 needle liver biopsy specimens with ACR in LRLT were examined using antibodies to CD4, CD8, and CD20. Formalin-fixed and paraffin-embedded liver tissues were used to maintain morphology. Immunohistological findings and RAI score according to the Banff schema were compared. In the results, mainly CD8-positive (CD8+), rather than CD4-positive (CD4+), cells were detected in the portal tract and were also found in bile duct epithelium and subendothelial areas of portal veins. The number of CD8+ cells increased according to ACR grade, whereas CD4+ cells tended to decrease. There were significant correlations between the presence of CD8+ cells (p = 0.0006) and CD4+ cells (p = 0.0003) and ACR severity. On the other hand, CD20-positive cells did not correlate with ACR severity (p = 0.472). The results indicate that CD8+ cells play important roles in ACR severity of LRLT, suggesting the number of CD8+ cells in liver tissue to be useful as a supplementary tool, in addition to RAI of the Banff schema, for objective evaluation of ACR severity.

Acute transplant glomerulitis, characterized by accumula-tionofinflammatorycellsinglomerularcapillaries,haslongbeen associated with graft rejection. Glomerulitis can bea feature of T cell-mediated acute rejection, but it is thetubulointerstital and vascular inflammation that makes thatdiagnosis and determines the Banff grade. An isolatedglomerulitis lesion with no associated interstitial inflam-mation, tubulitis or intimal arteritis has not previously beenrecognized as a feature of T cell-mediated rejection, andthus glomerulitis has never been integrated into the Banffcriteria for that diagnosis. In humoral rejection, neutrophilpolymorphs may accumulate in the glomerular capillariesin addition to mononuclear cells, and in 2003 glomerulitiswas included as a morphological component of the tis-sue injury in acute antibody-mediated rejection (1). Sincethen, glomerulitis along with peritubular capillaritis havebeen increasingly recognized components of the micro-circulatory injury associated with chronic active antibody-mediatedinjury(2),andinsomecasesofhumoralrejectionthese lesions are the only morphological evidence of graftinflammation.The grading of peritubular capillaritis (ptc score) hasrecently been incorporated into the Banff schema, fol-lowing appropriate reproducibility studies (3). Grading ofglomerulitis (g score) has been a component of Banfflesion scoring since the first version of the Banff classi-fication for renal allograft pathology in 1993 (4), and thecriteriaforscoringhavenotsignificantlyalteredsincethen.The score is determined from the percentage of glomeruliaffected by glomerulitis and whether the process issegmental or global. At the last Banff conference in 2009,glomerulitis scoring was identified as an area warrantingup-to-date studies, particularly to increase reproducibilityof the diagnosis.In this issue (5), Batal and colleagues from University ofPittsburgh Medical Center report one of the largest clini-copathological studies on glomerulitis (111 index biopsiesevaluated), including correlations with peritubular capillary(PTC) C4d deposition and donor-specific antibody (DSA)status. They assessed three separate histological grad-ing systems for glomerulitis, including percentage of af-fected glomeruli, most severely inflamed glomerulus andpresence of endocapillary occlusion by inflammatory cells.All three methods correlated with each other and showedclinicopathological correlations, but percentage of involvedglomeruli showed the most, including correlations withsubsequent graft failure, proteinuria, peritubular capillari-tis, PTC C4d+ and development of DSA.Thiscomprehensivestudyconfirmstheutilityofglomeruli-tis scoring, and the validity of the existing Banff approachto this lesion. The scoring method requires that everyglomerulus in a biopsy be evaluated; for reproducibilitythere needs to be clear guidelines for the cut-off betweenwhatiswithinnormallimitsandamilddegreeofglomeruli-tis. Batal et al. applied a longstanding WHO definitionfrom native kidney glomerular disease of ≥5 leukocytesper glomerulus in standard PAS-stained sections. Whilesevere cases of glomerulitis do often show unequivocalglomerularendothelialswelling,thisfeatureislikelytohavepoor inter-observer reproducibility, and is often not presentwithmilderglomerularinflammation.Theauthorsprovideastrong argument for not requiring endothelial enlargementto diagnose glomerulitis. The percentage cut-offs for Banffgrade of glomerulitis have not been critically assessedin this study, and a more uniform spread of glomerulitisscores would be desirable. Also, reproducibility of scoringhasnotbeenaddressed,butconsiderationshouldcertainlybe given to incorporating these refined definitions into fu-ture Banff criteria for glomerulitis.Some of the most clinically relevant findings of this studywere the association of glomerulitis with other markers ofhumoralrejection,thepersistenceofsevereglomerulitisinfollow-up biopsies following antirejection therapy and fur-ther confirmation of previous studies showing progressionfrom acute endocapillary glomerulitis to chronic transplantglomerulopathy.Thisstudydidnotfindanyassociationwithgrade of T cell-mediated rejection, and the significanceof glomerulitis in the absence of detectable DSA remains

This article will concentrate on two main areas of liver allograft pathology where there have been significant advances during the past few years. The first is rejection, which continues to be a common cause of graft dysfunction in the early postoperative period and a rare cause of graft failure. Histological assessment remains essential to confirm the diagnosis of rejection. A recently developed, internationally accepted schema (the Banff schema) for grading acute rejection and staging chronic rejection will be described. With increasing numbers of people surviving long-term following transplantation, the issue of disease recurrence is becoming increasingly important. The second part of the paper deals with the histological diagnosis of disease recurrence and the assessment of other changes seen in biopsies obtained more than 12 months following liver transplantation.

Accurate diagnosis and grading of rejection and other pathological processes are of paramount importance to guide therapeutic interventions in patients with pancreas allograft dysfunction. A multi-disciplinary panel of pathologists, surgeons and nephrologists was convened for the purpose of developing a consensus document delineating the histopathological features for diagnosis and grading of rejection in pancreas transplant biopsies. Based on the available published data and the collective experience, criteria for the diagnosis of acute cell-mediated allograft rejection (ACMR) were established. Three severity grades (I/mild, II/moderate and III/severe) were defined based on lesions known to be more or less responsive to treatment and associated with better- or worse-graft outcomes, respectively. The features of chronic rejection/graft sclerosis were reassessed, and three histological stages were established. Tentative criteria for the diagnosis of antibody-mediated rejection were also characterized, in anticipation of future studies that ought to provide more information on this process. Criteria for needle core biopsy adequacy and guidelines for pathology reporting were also defined. The availability of a simple, reproducible, clinically relevant and internationally accepted schema for grading rejection should improve the level of diagnostic accuracy and facilitate communication between all parties involved in the care of pancreas transplant recipients.

The relationship between acute renal allograft rejection and histopathologic biopsy alterations recognized by the Banff Schema as “borderline changes” is not clear. Some evidence supports the contention that about one third of patients with borderline infiltrates and clinical evidence of graft dysfunction do indeed have acute rejection, which, if left untreated, progresses to a histologically more advanced stage of rejection. Several investigators recognize that not all patients with mild tubulitis respond clinically to antirejection therapy; a significant number of these biopsy specimens display additional histological alterations. The most common concurrent lesions are chronic allograft nephropathy, arteriolar lesions consistent with calcineurin inhibitor toxicity, acute tubular necrosis, and obstructive nephropathy. Management of patients with borderline changes must tightly correlate the pathologic features and the clinical information.

The pathological findings on renal allograft biopsy specimens are often complex. By carefully defining the morphological features of acute allograft rejection, the Banff schema provides an important tool for the differential diagnosis of acute allograft dysfunction. This article reviews the criteria for diagnosis of rejection, and its differentiation from other inflammatory infiltrates in renal allograft biopsy specimens.

Chronic allograft nephropathy (CAN) is the major cause of graft loss, and early detection is desirable to avoid irreversible graft damage. We have evaluated a new technique of color Doppler quantification using Cineloop (Philips Medical Systems, Bothell, WA) imaging for noninvasive diagnosis of CAN.Provisional normal ranges were defined by pilot study (n=13) and prospectively tested in stable recipients in whom CAN was independently quantified by contemporaneous histology (n=67), using the Banff schema.The maximal fractional area (MFA, systolic color pixels/total area) was 28.7+/-9.7% in normal subjects and reduced to 18.8+/-8.0% in grade 1 and 12.5+/-6.4% in grade 2 CAN (both P0.001). The minimum color fractional area was reduced from 10.3+/-5.3% in normal subjects to 3.1+/-2.6% in grade 2 CAN (P0.001), but was less useful. Distance from peripheral color pixels to capsule increased in CAN grade 2 versus 0 (6.0+/-1.6 vs. 3.9+/-1.0 mm, respectively; P0.001). Calcineurin inhibitor nephrotoxicity reduced MFA (18.0+/-9.3 vs. 26.9+/-10.7%; P0.001) and other dynamic measurements. Parenchymal damage exerted minimal effect on resistance index, mean variance, and peak Doppler velocity. MFA (cutoff17.3%) can diagnose CAN (sensitivity 69%, specificity 88%, positive predictive value 86%) and severe CAN (sensitivity 87%, specificity 71%, negative predictive value 95%). Distance to capsule5 mm was less sensitive (49%) but more specific (91% alone, and 97% combined with MFA).In conclusion, quantitative Doppler ultrasound can reliably detect CAN and, although imperfect at correctly grading, allows recognition of significant tubulointerstitial damage for initiation of a confirmatory needle core biopsy.

This Practice Point commentary discusses Solez et al.'s most recent update to the Banff criteria for the classification of renal transplant pathology. The update focused on various aspects of antibody-mediated rejection, in particular the incorporation of a validated scoring system for peritubular capillary complement 4d staining and inflammation. A new scoring system for interstitial inflammation was also introduced, to be tested over the next 2 years. The report advocates the application of the Banff schema to zero-time and protocol biopsies, and several working groups have been set up to investigate the importance of new research data (including genomics and proteomics) for practical use. This commentary describes the new additions and proposals and places them in perspective.

A panel of recognized experts in liver transplantation pathology, hepatology, and surgery was convened for the purpose of developing a consensus document for the grading of acute liver allograft rejection that is scientifically correct, simple, and reproducible and clinically useful. Over a period of 6 months pertinent issues were discussed via electronic communication media and a consensus conference was held in Banff, Canada in the summer of 1995. Based on previously published data and the combined experience of the group, the panel agreed on a common nomenclature and a set of histopathological criteria for the grading of acute liver allograft rejection, and a preferred method of reporting. Adoption of this internationally accepted, common grading system by scientific journals will minimize the problems associated with the use of multiple different local systems. Modifications of this working document to incorporate chronic rejection are expected in the future.