The role of liver biopsy in evaluating acute allograft dysfunction following liver transplantation: a clinical histologic correlation of 34 liver transplants

One hundred six liver biopsy specimens from 34 orthotopic liver transplant (OLT) patients were examined and the histologic findings correlated with the clinical course of the patients to determine if specific morphologic patterns were associated with specific causes of acute allograft dysfunction. The principle causes of allograft injury in these patients appeared to be acute rejection and ischemic injury, with rarer cases of viral infection and biliary obstruction. Graft rejection causing transient liver dysfunction was associated with a mixed inflammatory infiltrate in the portal tracts and involving the interlobular bile ducts. Rejection resulting in severe, persistent dysfunction was associated with destruction and loss of the interlobular bile ducts or portal inflammation, followed by acute centrilobular hepatocyte necrosis. Ischemic liver injury was characterized by hepatocyte ballooning and/or hepatocyte necrosis. Ischemic injury causing transient graft dysfunction demonstrated focal, limited areas of hepatocyte necrosis or transient centrilobular hepatocyte ballooning. Severe ischemic injury resulting in persistent dysfunction caused diffuse hepatocyte necrosis or centrilobular ballooning followed by centrilobular hepatocyte loss and severe cholestasis with evidence of bile duct epithelial injury. The histologic patterns observed were not pathognomonic; radiologic studies, bile cultures, and other laboratory tests were necessary to rule out biliary or vascular obstruction and bacterial cholangitis. However, liver biopsies, especially serial biopsies, were helpful in suggesting the probable cause of liver dysfunction and in predicting subsequent allograft recovery or failure.     

Transplantationspathologie der Leber

Histopathology plays an important role in the diagnosis of graft complications following liver transplantation (LTX) and includes the diagnosis of underlying liver disease, assessment of the donor liver before LTX and control biopsies after LTX. Within the early period after LTX (time zero and first month) preservation/reperfusion injury, as well as hyperacute and acute rejection may occur. Surgical vascular or biliary complications can cause parenchymal morphological changes. Within 12 months following LTX, histological signs of opportunistic infections and chronic rejection are frequent findings and disease recurrence is typical beyond the first year. Drug toxicity in liver allograft recipients can be induced by immunosuppressive therapy or other drugs. A high percentage of adult patients reveal histological features of idiopathic chronic hepatitis 6 months after LTX. Histopathological differential diagnosis of the combined underlying causes or complications is often difficult.     

Histopathology of serial graft biopsies from liver transplant recipients

Serial graft biopsies (n = 78) from 12 liver transplant recipients (followed clinically up to 47 months) were studied with the use of histology, histochemistry, immunostaining, and electron microscopy. Planned-protocol needle biopsy specimens were taken from the graft before removal from the donor, 1 hour after transplantation, on the eighth day, and at yearly intervals. Nonprotocol biopsies were taken when deterioration of the clinical condition made a decision on changes in the regimen necessary. The protocol biopsies provided a baseline for graft condition and diagnostic histopathologic features. In these biopsies signs of hyperacute rejection, chronic rejection, or the recipient's previous liver disease were not observed. Mild acute rejection was regularly present on the eighth day, possibly due to a lag phase in the effect of immunosuppression. The syndromes in the nonprotocol biopsies included "pure" parenchymal cholestasis, reversible acute rejection resembling chronic active hepatitis, viral infection, and acute bacterial cholangitis. Each of these syndromes correlated with a separate histopathologic entity. Therefore, these entities proved to be of diagnostic value. It is concluded that a graft biopsy may substantially add to the pathogenetic interpretation, differential diagnosis, and management of major graft syndromes in orthotopic liver transplant recipients.     

Pathologic analysis of right-lobe graft failure in adult-to-adult live donor liver transplantation

Live donor adult liver transplantation (LDALT) utilizing right-lobe grafts is now acceptable as an alternative to cadaveric orthotopic liver transplantation (OLT). However, some LDALTs fail and require urgent OLT or result in recipient death. Our aim was to determine the basis of LDALT failure. Liver specimens from 49 LDALT recipients were evaluated and the findings correlated with clinical outcome. Ten patients (20.4%) had either early (< or = 1 month) or late (> 1 month) graft failure. Eight early failures, 7 of which occurred among our first 25 cases, were due to extensive liver parenchymal necrosis as a result of hepatic artery thrombosis (n=3), portal vein thrombosis (n=1), hyperperfusion syndrome (n=1), complete graft thrombosis (n=1) with Factor V Leiden on a regimen of therapeutic heparin (n=1), sepsis and concomitant graft dysfunction with venous outflow tract injury (n=1), and venous outflow tract thrombosis and parenchymal thermal injury with sepsis (n=1). Preoperative, intraoperative, or postoperative severe vessel wall injury was evident in 6/8 early failures. Two patients had late graft failure, 1 from recurrent hepatitis C and 1 with sepsis/multisystem organ failure. There were no significant differences in graft size, rejection episodes, or operative or ischemic times between patients with and without graft failure. In conclusion, LDALT failed in 10/49 (20%) of our patients, with 8/10 occurring within 1 month post-LDALT owing to vascular/thrombotic complications experienced during the early phase of our institutional experience. Perioperative vessel wall injury appeared to be a major factor in predicting early graft loss.     

Evolution of hepatitis B virus liver disease after hepatic replacement. Practical and theoretical considerations

The morphologic evolution of hepatitis B virus (HBV) liver disease in 45 hepatic allograft recipients who were HBV surface-antigen positive (HBs-Ag+) at the time of liver replacement and who survived for more than 60 days was studied by routine histologic and immunocytochemical analysis of serial pathology specimens. The findings in these patients were compared to a control group of 30 individuals who were immune to the HBV (anti-HBs antibody positive), but required hepatic replacement for other reasons. Eight of the forty-five (18%) HBsAg-positive patients have no serologic evidence of HBV reinfection after transplantation. All 37 remaining patients are reinfected; 21 (47%) developed chronic active hepatitis and/or cirrhosis, 3 (7%) developed submassive necrosis, and 6 (14%) developed chronic lobular hepatitis. One patient lost her graft to chronic rejection, despite reinfection with the B virus. Four other patients (9%) developed a chronic carrier state. No long-term follow-up biopsies were available in the remaining two patients. The histologic features associated with dysfunction related to recurrent HBV infection evolved from an acute to chronic phase and were similar to hepatitis B seen in nonallografted livers. Furthermore HBV-related lesions could be separated from rejection using routine histology alone. The only exception to this conclusion was the occurrence of a peculiar HBV-related lesion in two recipients, described herein. Immunohistochemical analysis demonstrated the presence of viral antigens in almost all cases. Hepatic inflammation also was commonly present during HBV disease and consisted mostly of accessory cells and T lymphocytes. Analysis of the effect of major histocompatibility complex matching revealed no clear association between the number of class I or II matches or mismatches and the development, or pattern, of active hepatitis in the allograft. Peculiar pathologic alterations in several of the biopsies and failed allografts after HBV reinfection suggests that, under special circumstances, the B virus may be cytopathic.     

New developments in renal transplant pathology

The renal transplant biopsy plays a central role in the diagnosis of renal allograft dysfunction; in particular in differentiating immune-mediated rejection from various infective, ischaemic and toxic pathologies. Recent advances have been made in refining the histological criteria for rejection diagnosis. The Banff’97 classification of renal allograft pathology has gained almost universal acceptance. In this classification, acute rejection is divided into three main types, tubulointerstitial, vascular and severe vascular, that differ in response to anti-rejection therapy and long-term prognosis. There remain, however, a number of challenges; interpretation of biopsies showing borderline changes, the diagnosis of humoral rejection and differentiating rejection from interstitial nephritis associated with viral infections present specific problems. There are potential applications for new molecular and immunohistochemical techniques in these areas. Other challenges arise from the application of the Banff classification. Recent validation studies have indicated that the reproducibility of some Banff criteria is low and that there are a number of histological features, not included in the Banff schema, that may be useful in rejection diagnosis.New roles for the transplant biopsy are developing in the management of patients with stable graft function, as indicated by measurement of serum creatinine. Protocol biopsies performed at regular intervals in the early post-transplant period may be used to predict subsequent development of chronic allograft nephropathy, the major cause of graft loss. The interpretation of these biopsies may be refined using morphometric techniques and immunohistochemistry for cytokines and matrix components. Protocol biopsies may also be used to diagnose sub-clinical rejection, and early evidence indicates that treatment of these histological rejections improves long-term graft outcome. The role of the transplant biopsy will continue to evolve with greater use of organs from marginal donors, improved understanding of the processes of graft injury and fibrosis, and the introduction of new immunosuppressive regimens.     

Effects of complement inhibition with soluble complement receptor-1 on vascular injury and inflammation during renal allograft rejection in the rat.

Complement is both an effector of the humoral immune response and a stimulator of leukocyte activation. To examine the influence of complement on the allograft response, we inhibited complement using recombinant human soluble complement receptor-1 (sCR1; TP10), in an unsensitized model of rat renal allograft rejection. Lewis to DA renal transplant recipients were treated daily with 25 mg/kg sCR1 or saline and sacrificed on days 1 to 5 after transplant. Transplanted organs were examined histologically and immunohistochemically for leukocyte subset markers and for the third component of complement, C3, and membrane attack complex deposition. A second set of recipients was followed from day 5 to day 9 to assess graft survival. sCR1-treated recipients displayed > 90% inhibition of plasma complement activity and a marked reduction in tissue C3 and membrane attack complex deposition. Inactivation of complement reduced the vascular injury such that there was almost complete sparing of vascular damage in day 5 sCR1-treated rats. There was a significant reduction in infiltrating leukocytes by day 5 after transplant, and complement inhibition delayed the time to reach a histologically defined end point of graft survival from 5 days in controls to 9 days in the sCR1-treated group. These results imply that the vascular and cell-mediated injury arises, in part, from complement activation. The partial inhibition of these injuries by sCR1 may have functional implications for strategies to inhibit allograft rejection.     

Effects of corticosteroids on HCV infection.

The risk factors for clinical recurrent hepatitis C in liver transplant recipients are not clearly defined. It has been suggested that the corticosteroids included in the treatments of patients undergoing allograft rejection might induce acute hepatitis by increasing HCV replication. In this study we investigated the effects of corticosteroid boluses on HCV viremia in liver allograft recipients treated for acute rejection. Since we had previously developed a model of HCV replication in peripheral blood mononuclear cells (PBMC) in vitro, we also studied the effects of corticosteroids on HCV replication in vitro. A transient peak of HCV viremia was observed in patients treated with corticosteroid boluses for an acute allograft rejection. In the cell cultures, corticosteroids induced an increase of the total amount of viral RNA detectable. Our results demonstrate that corticosteroids induce an increase of hepatitis C virus replication in vivo and in vitro.     

Evaluating and interpreting bile duct changes in liver allograft biopsies

Despite great advances in treatment of liver disease, liver transplant remains the only cure for end stage liver disease and hepatocellular carcinoma. Successful management of immediate and intermediate post-transplant events determines the overall graft outcome, and pathologists play a key role in achieving long-term graft survival. In evaluating liver allograft biopsies, bile duct changes frequently pose diagnostic dilemma as they could occur in association with or the result of various causes of graft dysfunction, but in which accurate classification and interpretation is key to subsequent management. The approach to interpreting these changes share some similarity to the non-transplant liver biopsy interpretation but several additional factors come into play in transplant setting sometimes making interpretation more complex. This review describes bile duct changes occurring in association with various clinical entities in liver allografts, such as acute and chronic rejection, obstruction, small-for-size syndrome, recurrent biliary diseases, and recurrent fibrosing cholestatic hepatitis C, and others, and discusses an approach to interpreting and reporting them.     

Management of post liver transplantation complications

Survival rate of liver transplanted patients is depending on management of postoperative complications. These complications include technical problems related to the operation, dysfunction of the allograft, and variety of medical complications. Differentiating and appropriately managing these diverse complications is a formidable challenge. Given the complexity of liver transplantation, it is not surprising that a variety of technical complication can occur following the operation. The most prominent of these include intraabdominal bleeding, hepatic artery thrombosis, portal vein thrombosis, and obstruction of or leak from the biliary anastomosis. In addition to these technical complications, each of which can result in dysfunction of the graft, there are a number of intrahepatic causes of graft dysfunction. The most common of these are allograft rejection, viral hepatitis and non-specific postoperative jaundice. In living related liver transplantation, primary graft non-function is rare. Accurate diagnosis and management of the various causes of graft dysfunction, whether intrahepatic or extrahepatic in origin, is very important.     

Recurrent hepatitis B in liver allograft recipients. Differentiation between viral hepatitis B and rejection.

The histologic findings in the original liver obtained from 9 liver allograft patients with active B virus hepatitis were compared with 28 posttransplant pathology specimens. All specimens were studied with the use of light and immunohistochemical microscopy in conjunction with pertinent clinical data. Eight of the 9 patients had chronic active hepatitis B (HB) with cirrhosis, prior to transplant, one of which had coexistent hepatocellular carcinoma. The ninth patient had fulminant hepatic necrosis secondary to acute HB prior to transplantation. In all of the patients with chronic HB prior to transplantation who survived more than 2 months after transplantation recurrent infection of the graft developed despite perioperative HB immunoglobulin therapy. The patient with acute fulminant hepatitis B pretransplant has done well postoperatively and has evidence of HB virus immunity (positive anti-HBs) 15 months after transplantation. Examination of tissue specimens obtained during episodes of allograft dysfunction in these 9 patients indicate that pathologic alterations of active HB infection of the allograft are associated with a preferential lobular insult, whereas those occurring in rejection preferentially involve portal tract structures. Serologic data combined with biopsy histopathologic data are essential in distinguishing between the two quite different events.     

Current aspects of liver allograft pathology

Liver allograft pathology continues to play an important role in the diagnosis and management of complications in the course of liver transplantation. This article summarizes important patterns of liver damage and also considers new aspects of transplant pathology from the literature. In the context of transplant rejection, late cellular rejection has aroused new interest. Histopathological changes in late rejection differ from acute cellular rejection and there seem to be similarities to de novo autoimmune hepatitis and idiopathic post-transplant hepatitis. Central perivenulitis is a typical change in late cellular rejection and should be differentiated from central toxic necrosis. Other important areas of transplant pathology include vascular and biliary changes resulting from surgical complications or as sequelae of immunosuppressive therapy. Furthermore, disease recurrence plays an important role and combined patterns of disease poses a challenge for the pathologist.     

Hepatitis C-associated granulomas after liver transplantation: morphologic spectrum and clinical implications

Liver granulomas have been described in biopsy specimens from people with de novo chronic hepatitis C virus (HCV) infection and in allograft biopsy specimens from recipients of transplants for HCV-related liver disease. The latter have not been well studied, and there are no data regarding the prevalence, morphologic spectrum, and clinical significance of HCV-associated granulomas after liver transplantation. We observed granulomas in allograft liver biopsy specimens of 4 (8%) of 53 recipients of transplants for HCV-related end-stage liver disease during a 3-year period. Initial appearance of granulomas ranged from 4 to 41 weeks after transplantation. Lobular and portal nonnecrotizing, epithelioid granulomas and lobular microgranulomas were observed, with the latter predominating. Serum transaminase and alkaline phosphatase levels were significantly higher in patients with granulomas than in age- and sex-matched control subjects, but histologic disease activity, cellular rejection scores, HCV genotypes, viral titers, and retransplantation rate owing to recurrent disease were not significantly different. Our study suggests that a granulomatous response to HCV infection occurs in a subset of patients after transplantation; however, this histologic finding does not portend a worse clinical outcome.     

Liver allograft rejection in sensitized recipients. Observations in a clinically relevant small animal model.

A sequential analysis of liver allograft rejection in sensitized rats using immunopathological and ultrastructural microscopy is described. Lewis rats were primed with four ACI skin grafts and challenged with an arterialized ACI orthotopic liver allograft 14 to 17 weeks later. The sensitization resulted in a mix of IgG and IgM lymphocytotoxic antibodies at a titer of 1:512 at the time of transplantation. Specificity analysis of pretransplant immune sera revealed a predominance of IgG anti-class I major histocompatibility complex (RT1) antibodies with a minor IgG fraction showing apparent endothelial cell specificity (non-RT1). This level of sensitization was associated with accelerated graft failure in 3 to 5 days from mixed humoral and cellular rejection. Sequential analysis of serial posttransplant graft biopsies revealed diffuse vascular IgG deposition and platelet thrombi in portal veins and periportal sinusoids within 3 minutes after reperfusion. This was followed by endothelial cell hypertrophy and vacuolization, periportal hepatocyte necrosis, arterial spasm, focal large bile duct necrosis, and hilar mast cell infiltration and degranulation. However, the liver allografts did not fail precipitously and hyperacute rejection was not seen. Kupffer cell phagocytosis of the sinusoidal platelets began as early as 30 minutes posttransplant and by 24 hours, the platelet thrombi had decreased. Cholangioles appeared focally at the edge of the limiting plates by 2 to 3 days, apparently in response to earlier periportal hepatocyte damage. A mononuclear portal and perivenular infiltrate became evident at 3 days, and graft failure was attributed to both antibody and cell-mediated rejection (Furuya et al: Preformed lymphocytotoxic antibodies: Hepatology 1992, 16: 1415-1422). The model described resembles observations in crossmatch positive human liver allograft recipients. The mechanisms of hepatic graft resistance to antibody mediated rejection and the possible long term consequences of early damage to the biliary tree are discussed.     

De novo cancers and post-transplant lymphoproliferative disorder in adult liver transplantation

De novo cancer is one of the most serious complications after organ transplantation. Chronic immunosuppression, viral agents, pretransplant chronic alcohol-induced and other addictive behavior-induced injury are important conditions associated with the development of de novo cancers in solid organ transplants. The aim of the study was to evaluate types and clinical course of de novo cancers in adult liver transplant recipients. Data regarding 502 adult patients who underwent to 554 liver transplantations have been collected. Sex, age at transplantation, immunosuppressive regimen, time from transplantation to diagnosis of cancer, cancer type, surgical and non-surgical treatments and follow-up time have been analyzed as well as acute rejection episodes and viral status. Thirty patients developed 31 de novo cancers. The predominant tumors were carcinoma of the skin, lymphomas and Kaposi's sarcoma. Kaposi's sarcoma and lung cancer were associated with greater mortality. In lymphomas and Kaposi's sarcoma, a high rate of graft involvement was observed. In liver transplant recipients, de novo cancers demand strategies focusing on prophylactic and careful long-term screening protocols. Lymphomas and Kaposi's sarcoma should be ruled out in all patients with clinical manifestations of chronic biliary obstruction.     

Beta-2-microglobulin expression in the liver after liver transplantation.

The distribution of major histocompatibility complex (MHC) class 1 antigens was studied in the liver after transplantation by immunoperoxidase staining for beta-2-microglobulin (beta 2m), a subunit of the class 1 antigen system. Paraffin wax sections were examined from 25 "time zero" biopsy specimens, taken immediately after insertion of the graft, and 87 biopsy specimens taken after transplantation in seven diagnostic categories: acute cellular rejection (n = 22); resolving acute rejection (n = 8); chronic rejection (n = 22); pure cholestasis (n = 14); ischaemia/infarction (n = 5); biliary obstruction (n = 8); massive haemorrhagic necrosis (n = 8). Staining was graded semiquantitatively on a scale of 0-3+ in bile ducts, hepatocytes, sinusoidal lining cells and vascular endothelium. Using the "time zero" biopsy specimens as a baseline for comparison, increased expression of beta 2m was seen in bile ducts, hepatocytes, and endothelial cells after transplantation. These changes were most pronounced in cases of rejection but also occurred in other graft conditions. The degree of hepatocyte and endothelial staining was significantly higher in cases of rejection and massive haemorrhagic necrosis than in the other categories. These findings may have implications for the pathogenesis and diagnosis of rejection of the transplanted liver.     

Treatment of recurrent HCV infection after liver transplantation

End-stage liver disease associated with hepatitis C virus (HCV) infection is the most common indication for orthotopic liver transplantation (OLT) and accounts for 50% of these procedures in Spain and 42% of OLT performed in the United States. Recurrent infection with HCV after OLT, however, is almost universal and is associated with substantial morbidity, mortality, and graft loss. In contrast to immunocompetent individuals, HCV infection in immunosuppressed transplant recipients usually has an accelerated course. Acute hepatitis develops in approximately 75% of HCV recipients in the first six months following OLT. By the fifth postoperative year, over 80% of HCV-infected liver transplant recipients will develop histologic evidence of chronic allograft injury secondary to hepatitis C, with up to 30% developing cirrhosis. While the choice of calcineurin inhibitor has not been clearly shown to affect the histologic recurrence of hepatitis C or the frequency of rejection in HCV-infected recipients, cumulative exposure to corticosteroids is associated with increased mortality, higher levels of HCV viremia and more severe histologic recurrence. There have been no well-controlled, large, prospective, multicenter and randomized clinical trials to determine the optimal approach to the treatment of recurrent HCV infection following OLT. Most published studies were small, lacked controls, had short follow-up periods, and were devoid of histologic analysis. Furthermore, most of the published studies are largely incomparable due to differences in the definition of recurrent hepatitis C, timing of anti-HCV therapy administration relative to transplantation, the drugs and doses used and regimens employed, and the study end points assessed (i. e. biochemical, virologic and histologic end points have not all been consistently investigated). In lieu of large studies in post-transplant patients, monotherapy with conventional interferon or monotherapy with pegylated interferon should be considered in recipients with histologically confirmed recurrence of HCV infection. The role of hepatitis C immunoglobulin and new imunosuppression agents in the management of post-transplant HCV infection is still evolving.     

Expression of Epstein-Barr virus-encoded small RNA (by the EBER-1 gene) in liver specimens from transplant recipients with post-transplantation lymphoproliferative disease.

BACKGROUND. Epstein-Barr virus (EBV)-associated post-transplantation lymphoproliferative disease (PTLD) develops in 1 to 10 percent of transplant recipients, in whom it can be treated by a reduction in the level of immunosuppression. We postulated that the tissue expression of the small RNA transcribed by the EBER-1 gene during latent EBV infection would identify patients at risk for PTLD. METHODS. We studied EBER-1 gene expression in liver specimens obtained from 24 patients 2 days to 22 months before the development of PTLD, using in situ hybridization with an oligonucleotide probe. Control specimens were obtained from 20 recipients of allografts with signs of injury due to organ retrieval, acute graft rejection, or viral hepatitis in whom PTLD had not developed 9 to 71 months after the biopsy. RESULTS. Of the 24 patients with PTLD, 17 (71 percent) had specimens in which 1 to 40 percent of mononuclear cells were positive for the EBER-1 gene. In addition, 10 of these 17 patients (59 percent) had specimens with histopathological changes suggestive of EBV hepatitis. In every case, EBER-1-positive cells were found within the lymphoproliferative lesions identified at autopsy. Only 2 of the 20 controls (10 percent) had specimens with EBER-1-positive cells (P < 0.001), and such cells were rare. CONCLUSIONS. EBER-1 gene expression in liver tissue precedes the occurrence of clinical and histologic PTLD. The possibility of identifying patients at risk by the method we describe here and preventing the occurrence of PTLD by a timely reduction of immunosuppression needs to be addressed by future prospective studies.     

An immunohistochemical evaluation of C4d deposition in pediatric inflammatory liver diseases

C4d is a marker of the activated complement cascade used to assess the humoral component of rejection, mostly in kidney allograft transplants. The role of C4d deposition has recently been addressed in hepatic allograft but has never been tested in a series of inflammatory liver diseases without previous liver transplantation. The aim of this study was to compare the immunohistochemistry profile of C4d deposition in a pediatric population, between a cohort of patients with autoimmune hepatitis (AIH) and a series of patients with chronic viral hepatitis B or C. Immunohistochemical analysis was performed on 64 liver biopsies. C4d deposition was observed in 25 (83%) of 30 AIH biopsies examined, in 6 (40%) of 15 hepatitis C biopsies, and in 17 (89%) of 19 hepatitis B biopsies. No expression of C4d was observed in 4 noninflammatory liver specimens used as negative controls. In the AIH group, a staining of the periportal sinusoids was often observed, as well as focal periductal reinforcement. Centrolobular vein staining was observed in the 3 hepatitis groups with a higher frequency in viral hepatitis B biopsies. Regardless of the etiology, lymphoid aggregates demonstrated an accentuation of the staining. These results confirm a role for a humoral immune response in pediatric autoimmune as well as in viral hepatitis. The relative ratios of positive cases imply that this immunostaining does not represent a strong diagnostic criterion in the differentiation between viral hepatitis and AIH. However, differences in the pattern of the staining were observed, depending on the etiology of the disease. The high prevalence of C4d reactivity in viral hepatitis strongly suggests that C4d does not represent a useful marker in the differentiation between acute rejection and viral hepatitis relapse in liver transplants.     

Frozen-section analysis of allograft renal biopsy specimens. Reliable histopathologic data for rapid decision making

Rapid tissue diagnosis during acute events associated with renal transplantation is often necessary to permit immediate decisions regarding initiation or modification of therapy. To achieve this, we performed frozen section analyses with cryoprotected alcoholic Bouin's-fixed tissue, which permits evaluation within 2.5 hours. During a 30-month period, 200 allograft biopsies were performed; 68 frozen sections were obtained when deemed necessary by the clinical team. We compared frozen-section diagnoses with those following regular evaluation of the biopsy specimen. Agreement in diagnoses occurred in 61 (88.4%) of 69 specimens. Acute rejection was the dominant diagnosis (n = 39); others were acute tubular necrosis, cyclosporine toxicity, chronic rejection, and infection. Major misdiagnoses included acute vascular processes (three capillary and/or venous thromboses and one vascular inflammation); acute cellular rejection was missed in two cases, reflecting a sampling error. Secondary diagnoses not of immediate therapeutic importance were detected in seven frozen sections and missed in nine. These included chronic glomerulopathies, nephrosclerosis, and mild chronic rejection. Although acute vascular phenomena may be difficult to recognize in frozen sections, we conclude that allograft biopsy frozen-section analysis is a valuable part of the care of transplant recipients.