The diagnostic and prognostic value of renal allograft biopsy

Evolution of human kidney allograft pathology diagnostics through 30 years of the Banff classification process

The second half of the previous century witnessed a tremendous rise in the number of clinical kidney transplants worldwide. This activity was, however, accompanied by many issues and challenges. An accurate diagnosis and appropriate management of causes of graft dysfunction were and still are, a big challenge. Kidney allograft biopsy played a vital role in addressing the above challenge. However, its interpretation was not standardized for many years until, in 1991, the Banff process was started to fill this void. Thereafter, regular Banff meetings took place every 2 years for the past 30 years. Marked changes have taken place in the interpretation of kidney allograft biopsies, diagnosis, and classification of rejection and other non-rejection pathologies from the original Banff 93 classification. This review attempts to summarize those changes for increasing the awareness and understanding of kidney allograft pathology through the eyes of the Banff process. It will interest the transplant surgeons, physicians, pathologists, and allied professionals associated with the care of kidney transplant patients.

Pathology of the kidney allograft

The kidney biopsy still represents the best approach to diagnose renal transplant complications. It is considered the gold standard in the diagnosis of rejection and non-rejection complications. Although invasive, it is a safe procedure with a very low complication rate. With adequate sampling, changes related to antibody-mediated rejection (ABMR) and T-cell mediated rejection (TCMR) can be identified. However, the pathologist needs to be aware of the many other complications, not related to rejection, that can affect the allograft function. Examples include viral infections, drug toxicity, systemic diseases such as hypertension and diabetes, and recurrent or de novo glomerulopathy, among others. In this article, we review the recent classification of pathology of the kidney allograft, with reference to recent consensus reached at the most recent Banff renal allograft classification meetings, and also highlight common non-rejection complications of the kidney transplant.

Nature, timing, and severity of complications from ultrasound-guided percutaneous renal transplant biopsy

We sought to review our kidney transplant biopsy experience to assess the incidence, type, presenting symptoms, and timing of renal transplant biopsy complications, as well as determine any modifiable risk factors for postbiopsy complications. This is an observational analysis of patients at the University of Wisconsin between January 1, 2000, and December 31, 2009. Patients with an INR ≥1.5 or platelet counts less than 50 000 were not biopsied. An 18-gauge needle was used for biopsy. Over the study period, 3738 biopsies were performed with 66 complications (1.8%). No deaths occurred. A total of 0.7% were mild complications, 0.7% were moderate complications, 0.21% were severe complications, and 0.19% were life-threatening. Most complications occurred within the 4-h postbiopsy period, although serious complications were often delayed: 67% of complications requiring surgical intervention presented greater than 4 h after biopsy. Biopsy within 1 week of transplant had a 311% increased risk of a complication. Postbiopsy reduction in hematocrit and hemoglobin at 4 h was associated with a complication. In conclusion, life-threatening complications after renal allograft biopsy occurred in 0.19% of patients. Most complications occurred within 4 h postprocedure; however, many serious complications occurred with a time delay after initially uneventful monitoring. The only clinically significant laboratory predictor of a complication was a fall in the hematocrit or hemoglobin within 4 h. Patients biopsied within a week of transplant were at the highest risk for a complication and should therefore be most closely monitored.

The significance of histological diagnosis in renal allograft biopsies in 2014

In 2014, the renal allograft biopsy still represents the best available diagnostic 'gold' standard to assess reasons for allograft dysfunction. However, it is well recognized that histological lesion observed in the biopsy is of limited diagnostic specificity and that the Banff classification as the international diagnostic standard represents mere expert consensus. Here, we review the role of the renal allograft biopsy in different clinical and diagnostic settings. To increase diagnostic accuracy and to compensate for lack of specificity, the interpretation of biopsy pathology needs to be within the clinical context, primarily defined by time post-transplantation and patient-specific risk profile. With this in mind, similar histopathological patterns will lead to different conclusions with regard to diagnosis, disease grading and staging and thus to patient-specific clinical decision-making. Consensus generation for such integrated diagnostic approach, preferably including new molecular tools, represents the next challenge to the transplant community on its way to precision medicine in transplantation.

Biopsy of the transplanted kidney

This article describes the current state-of-the-art technique of percutaneous transplant renal biopsy. A brief overview of the history of transplant renal biopsy is given. The indications and contraindications are discussed, including pre- and postprocedure patient management. The technique of the procedure and the devices that are available in the market are described.

Histopathologic findings and classification of feline renal transplants

Seventy-seven feline transplant kidney specimens, obtained from 1 to 3,183 days (9 years) after transplantation, were reevaluated histologically and classified on the basis of the Banff '97 guidelines for human renal transplant kidneys. Overall, this classification system appeared useful in detecting rejection reactions and confirmed the finding in humans that biopsies can diagnose subclinical rejection and therefore are an important diagnostic tool for the follow up of renal transplants. However, on the basis of serum creatinine values, the severity of the acute or active and chronic lesions was not accurately reflected by this scoring system. This is thought to be due to the significant differences in histologic rejection patterns, especially in acute or active rejection, in cats when compared with humans. Tubulitis, lymphocytic glomerulitis, and vasculitis, which are the main pillars of the Banff '97 acute or active rejection scoring system, are either rare or not found in cats. The presence of significant necrotizing glomerulitis and vasculitis in feline renal transplants might imply that the rejection is complicated by acute antibody-mediated rejection. Alternatively, cyclosporine toxicity also should be considered because some of these kidneys show other signs of cyclosporine toxicity. Finally, the significance of subcapsular and interlobular phlebitis, rarely described in human rejection reactions but a distinct entity in cats, is unknown. From this study, it is clear that there are significant differences in the histology of acute or active rejection between humans and cats and that a better understanding of the histologic appearance of renal allografts will be especially beneficial for treatment and prognostic purposes.

A blinded retrospective analysis of renal allograft pathology using the Banff schema: implications for clinical management

BACKGROUND

We sought to determine whether diagnoses established through the Banff schema for evaluation of renal allograft pathology have implications for clinical management, compared with diagnoses established using descriptive terminology.

METHODS

All patients included in this study had mild to severe allograft rejection diagnosed, and, as part of a therapeutic protocol, they received OKT3 as primary anti-rejection therapy. We conducted a retrospective review of their renal allograft biopsy specimens and reclassified them, using the Banff schema, without knowledge of clinical information, laboratory data, or previous biopsy interpretation. Although there is no strict correspondence between descriptive diagnostic terminology and the criteria used in the Banff schema, for the purpose of comparisons, the following approximation was used: mild and mild to moderate rejection=Banff borderline and Banff grade 1, moderate and moderate to severe rejection=Banff grades 2A and 2B, and severe rejection=Banff grade 3. The diagnosis was considered concordant when the diagnosis by descriptive terminology and Banff grading were within the adopted approximation.

RESULTS

Of 96 biopsies specimens with mild to severe allograft rejection, 10 were insufficient for diagnosis, and three had changes of chronic allograft rejection. Of the remaining 83 biopsy specimens, 34 (41%) were concordant in interpretation of rejection grades, whereas 49 (59%) were discrepant. The greatest degree of concordance was in grades 2A (66.7%, 18 of 27) and 2B (64.7% 11 of 17), and the lowest was in the borderline category (11.8%, 2 of 17). The greatest degree of discrepancy was in normal and grade 3 (100%, 3 of 3 and 2 of 2, respectively), and the lowest was in grade 2A (33.3%, 9 of 27). Although primary anti-rejection therapy with OKT3 resulted in a high reversal rate of rejection (98%), there were 5 deaths, 12 graft loses, six episodes of serious infections, and three malignancies in this group of patients during a mean follow-up period of approximately 38 months.

CONCLUSIONS

Because patients with borderline changes and grades 1 and 2A rejection may be treated differently from patients with higher grades (2B and 3), the use of the Banff schema may allow for better adjustment of immunosuppressive therapy in response to specific grades of acute allograft rejection and may result in decreased complications of immunosuppressive therapy.

The US multicenter double-blind, randomized, phase III trial of thymoglobulin versus atgam in the treatment of acute graft rejection episodes following renal transplantation: rationale for study design

In this study intended to establish equivalence between two antibody therapies for acute rejection in kidney transplant recipients, it was important to develop a rigorous protocol. Assurance of the presence of acute rejection was imperative. Therefore, due to the lack of literature support for clinical assessment of renal dysfunction, histologic diagnosis of acute rejection was required for enrollment in the study. Likewise, supportive literature for a correlation between response to anti-rejection therapy and the severity of rejection lead to the decision that the study should be stratified by a measurement of rejection severity for which Banff criteria were used. Finally, quantification of the response to therapy was also measured against the available literature and a large, newly developed international database of kidney transplant rejection episodes (the Efficacy Endpoints database) where serum creatinine, expressed as a percentage of the baseline level at the time of rejection was shown to be the most effective, available clinical marker of rejection response. Therefore, the US Multicenter Phase III Trial for comparing Thymoglobulin to Atgam in the treatment of acute rejection exhibits a unique and detailed study design that could be implemented in future trials as well as in clinical practice to improve assessment of outcomes.

Early protocol renal allograft biopsies and graft outcome

To evaluate whether biopsies performed early after transplantation in stable grafts can predict graft failure due to chronic transplant nephropathy, a protocol biopsy was performed at three months in 98 patients treated with antilymphocytic antibodies, cyclosporine and prednisone. Patients were followed for 58 +/- 16 months. Histological diagnosis according to the Banff schema were: normal (N = 41), borderline changes (N = 12), chronic transplant nephropathy (CTN; N = 30), CTN associated to borderline changes (N = 11) and acute rejection (N = 4). Biopsies displaying acute rejection were not considered for statistical analysis. Since clinical characteristics of patients displaying CTN either with or without tubulitis were not different, biopsies were grouped as presence or absence of CTN. Patients displaying CTN had an increased incidence of acute rejection before performing biopsy (24.3 vs. 3.9%, P = 0.003), a higher mean cyclosporine level until biopsy (242 +/- 74 vs. 214 +/- 59 ng/ml, P = 0.049) and a lower actuarial graft survival (80.5% vs. 94.4%, P = 0.024). We conclude that early protocol biopsies are useful to detect patients at risk of losing their graft due to chronic transplant nephropathy.

The correlation of Banff scoring with reversibility of first and recurrent rejection episodes

Recurrent acute rejection remains a significant problem for recipients of renal allografts, with a large proportion of patients progressing to graft loss. The newly introduced Banff schema was used to determine whether the histologic pattern of acute rejection (severity and renal compartment scoring) could discriminate recurring from nonrecurring rejections and to examine whether objective rejection scoring had predictive value for rejection reversal and outcome. A total of 67 biopsies obtained from 50 patients with acute rejection were examined for the occurrence of recurrent allograft rejection. All patients were maintained on a cyclosporine-based triple immunosuppressive protocol and had biopsy-proven acute rejection without chronic changes. Rejection recurred in 13 patients (26%), of whom 4 further developed a third rejection. The majority of the patients developed this first rejection within 2 months posttransplantation. Demographics, prebiopsy renal function, immunosuppression, and peak serum creatinine level at the time of biopsy were similar in patients with multiple and single rejection. Peak levels of reactivity to panel of lymphocytes seemed higher in the group of patients with recurrent rejection, whereas HLA matching was similar for all patients. Banff scores for acute rejection did not discriminate patients at risk of rejection recurrence who had lower vascular (0.6 vs. 1.2), tubular (0.6 vs. 1.1), and lower cumulative SUM (3.0 vs. 4.5) scores on their first rejection when compared with patients with one rejection. Histological scoring was, however, significantly different when first and third episodes were compared in the same patient, indicating increased rejection severity with recurrence. Moreover, the rate of reversal of recurrent rejection by anti-lymphocyte therapy was significantly less than that of first rejection (P<0.05). In conclusion, these data demonstrate that Banff scoring correlated with rejection reversal and steroid responsiveness, yet rejection recurrence was independent of histological score of the first rejection. Furthermore, Banff schema provided an objective histological correlation to the poor clinical outcome seen with recurrent rejection. The data also suggest that patients with early mild rejection continue to be at risk for recurrence and graft loss.

Correlation between Banff classification, acute renal rejection scores and reversal of rejection

The Banff classification of acute rejection is based on histologic grades and scores for borderline changes, glomerular, vascular, interstitial and tubular lesions. We reviewed 56 episodes of acute rejection occurring in 44 kidney allograft recipients (30 cadaveric and 14 living donor transplants), comparing Banff classification to degree of reversibility of rejection. Rejection reversal was defined as complete if serum creatinine returned < or = 25% of baseline, partial if creatinine was > 25% to < 75% of baseline, and irreversible if creatinine was > or = 75% of baseline or graft loss occurred. Eight biopsies were classified as borderline (SUM score 1.6 +/- 0.5), 14 grade I (SUM score 3.3 +/- 0.4), 19 grade II (SUM score 4.2 +/- 0.3), and 15 grade III (SUM score 8.5 +/- 0.4). SUM distinguished borderline and grade III rejections, but not grades I and II. Clinically, grade and SUM score correlated with rejection reversal. Complete reversal of rejection occurred in 93% of patients with grade I rejection, while 47% of patients with grade III had irreversible rejection. The mean SUM for complete reversal was 3.9 +/- 0.34 and was different from SUM of partial (6.0 +/- 0.86) and irreversible (8.5 +/- 0.93), P < 0.006. Meanwhile, vascular scores were similar for rejections with complete (0.9 +/- 0.2) or partial (1.0 +/- 0.4) reversal, but significantly higher in those with irreversible rejection (3.0 +/- 0.4, P < 0.000). Likewise, mean scores for tubulitis and interstitial inflammation were significantly higher for irreversible rejection. Resolution of rejection by steroids was correlated to low vascular score (steroid sensitive 0.65 +/- 0.25 vs. steroid resistant 1.42 +/- 0.18, P < 0.01), and low SUM score (steroid sensitive 3.7 +/- 0.5 vs. steroid resistant 5.22 +/- 0.43, P < 0.04). Neither scores for tubulitis nor interstitial cellular inflammation were predictive of steroid sensitivity. These data demonstrate that Banff scoring has clinical relevance in predicting rejection reversal and has implications to first-line therapy of rejection episodes.

Diagnostic and predictive value of an immunohistochemical profile in asymptomatic acute rejection of renal allografts

We have retrospectively studied the diagnostic and predictive value of immunohistochemical characterization of adhesion molecules (ICAM-1, CD54, VCAM-1) and HLA-DR antigen in a homogeneous clinical group of 36 patients. Between 1 January 1991 and 31 January 1993, 130 patients received a kidney transplant in our unit. Biopsies of renal allografts were only performed in asymptomatic patients who had graft dysfunction, revealed by an isolated serum creatinine increase. Available frozen samples were included in this study (n = 44). The 35 cases of acute rejection diagnosed by biopsy corresponded to mild acute rejection according to the Banff classification criteria. First, we compared the expression of HLA-DR, ICAM-1 and VCAM-1 to morphological data to determine if the immunohistochemical data improved the histopathological diagnosis when the interstitial infiltrate was mild with slight tubulitis. We also studied the phenotype of infiltrating cells with monoclonal antibodies directed against T helper cells, T cytotoxic-suppressor cells, activated T cells and macrophages. Expression on tubular epithelium and density of each type of cell was graded semiquantitatively. Expression of HLA-DR, ICAM-1 and VCAM-1 was observed on tubular epithelium and endothelium in both acute rejection and other causes of graft dysfunction, limiting its diagnostic value. Activated T cells expressing CD69-AIM (activation inducer molecule) and/or HLA-DR were frequently observed in acute rejection (24/35 (69%) and 25/35 (71%) respectively) but not in other causes of renal dysfunction. We then studied the prognostic usefulness of the immunohistochemical profile in acute rejection. Of 27 patients, 12 had a progressively decreased renal function or returned to dialysis within one year after transplantation while the other 15 had a stable graft function after at least 18 months of follow-up. In the group of bad prognosis (n = 12), corticosteroid-resistant rejection episodes were significantly more frequent (p < 0.01). In this group, nine patients had an overexpression of HLA-DR on tubular epithelium versus one patient in the group of stable graft function (chi 2c = 10.57, p < 0.002). Seven patients included in the group of bad prognosis showed tubular overexpression of both ICAM-1 and VCAM-1 versus one patient in the other group chi 2c = 6.23, p < 0.02). Moreover, patients of the first group had a significantly higher number of interstitial macrophages as compared with those who had stable graft function (chi 2c = 4.87, p < 0.01). Thus, our data show that the immunohistochemical profile studied is of little value in the diagnosis of renal allograft rejection. However, an intense tubular expression of HLA-DR and/or both ICAM-1 and VCAM-1, and a high number of interstitial macrophages are significantly related to unfavorable graft outcome.

Histopathologic findings associated with a chronic, progressive decline in renal allograft function

The relationship between specific histopathologic findings of chronic rejection (CR) and the clinical course of renal transplant recipients with a chronic progressive decline in allograft function (CPDAF) is unknown. We used one or two hinged regression lines, fitted by least-squares to serial creatinine clearances, to define the onset and clinical course of CPDAF. Biopsies (N = 100) from patients transplanted from 1978 to 1982 were studied retrospectively. Interstitial fibrosis, tubular atrophy, and fibrointimal arterial narrowing were more pronounced in biopsies obtained after, but not before the onset of CPDAF. Interstitial hemorrhage, an infrequent finding in acute vascular rejection, preceded the onset of CPDAF, but the more common histologic findings of acute cellular rejection did not. The severity of histologic features of CR (as reflected by a score combining fibrointimal arterial narrowing, interstitial fibrosis, tubular atrophy, glomerular sclerosis, glomerular mesangial expansion, and glomerular basement membrane reduplication) correlated with the duration of subsequent allograft survival (r = -0.65, P less than 0.001). Glomerular size increased after transplantation, but was not different in patients with or without CPDAF, suggesting that mechanisms related to compensatory hypertrophy did not play a major role in the pathogenesis of CR. In summary, the histologic findings of CR did not predict the onset of CPDAF, did not distinguish whether the pathogenesis was mediated by immune or nonimmune events, but did correlate with the duration of subsequent allograft survival.

T-cell receptors and ICAM-1 expression in renal allografts during rejection

Sixty-two biopsies taken from 38 kidney grafts were studied for 15 histological and 10 immunohistological parameters. The biopsies were divided into three groups, according to the clinical diagnosis at the time they were performed: group 1, rejection (n = 43); group 2, other causes of dysfunction (n = 10); and group 3, stable function (n = 9). Histological signs of acute rejection included diffuse interstitial infiltrate, tubular basement membrane damage, mononuclear leukocyte infiltration, and congestion of the peritubular capillaries. Immunoperoxidase staining with monoclonal antibodies to ten markers showed a statistically significant association between detection of T-cell receptor subunits alpha-beta (TcR2) and gamma-delta (TcR1) on infiltrating lymphocytes and of intercellular adhesion molecule-1 (ICAM-1) in tubular cells and acute rejection. These results suggest that T-cell receptors and ICAM-1 may be useful markers to differentiate acute rejection from renal graft dysfunctions due to other abnormalities.

Value of percutaneous core needle biopsy in the differential diagnosis of renal transplant dysfunction

The value of percutaneous core needle biopsy in the differentiation of rejection from other causes of renal allograft dysfunction, and its subsequent effect on patient management were assessed in 64 consecutive biopsies performed on 34 patients in whom the clinical diagnosis was was uncertain. A complete clinical, biochemical and radiographic assessment was made in each patient before biopsy. Only 1 biopsy (1.6 per cent) yielded tissue inadequate for evaluation, while another biopsy caused a renal artery pseudoaneurysm that ruptured and resulted in graft loss. In 27 of these 64 biopsies (42 per cent) the results differed from the pre-biopsy diagnosis and directly affected patient management, particularly the use of steroids. The remaining biopsy specimens were helpful to confirm uncertain clinical impressions, and allowed accurate counseling for patients and family. Biopsies were of special usefulness in separating acute rejection from complications, such as acute tubular necrosis, cytomegalovirus infections, recurrence of original disease, cyclosporin toxicity and acute superimposed-upon chronic rejection. Of 64 biopsies 22 (34.3 per cent) demonstrated the absence of rejection and 8 demonstrated chronic rejection (12.5 per cent), thereby averting the use of steroids in 46.8 per cent of the patients. All patients with evidence of severe small vessel disease and/or antibody-mediated rejection eventually lost the grafts, including 2 with cytomegalovirus glomerulopathy who also suffered such vascular changes. These data highlight the extreme usefulness of needle biopsy in the evaluation and management of renal allograft dysfunction.

Urological complications associated with a kidney transplant biopsy: report of 3 cases and review of the literature

During the last 12 years 400 renal allograft biopsies have been performed at this institution to facilitate the differential diagnosis of post-transplant renal dysfunction. Of these cases significant urological complications occurred in 3. In 1 patient a caliceal cutaneous fistula developed after an open surgical biopsy, which required nephrostomy drainage for 6 months. The other 2 patients had needle biopsies and, subsequently, anuria occurred from ureteral blood clots. The problem resolved spontaneously after 23 hours in 1 patient and after 30 hours in the other. The complications in these 3 patients are believed to have resulted from a deeper biopsy and consequent damage to the medullary vasculature and the pelviocaliceal collecting system. Because of these and other potential problems, renal transplant biopsies should be performed by experienced staff, after careful consideration of the risk/benefit ratio at each individual setting.