The impact of chronic Epstein-Barr virus infection on the liver graft of pediatric liver transplant recipients: A retrospective observational study.

BACKGROUND: Chronic high Epstein-Barr virus loads (CHEBV) are commonly observed in pediatric liver transplant patients. However, it is unclear how CHEBV impacts the liver graft. The aim of this study was to clarify the clinical and pathological impacts of CHEBV on the liver graft. METHODS: From 2012 to 2020, we retrospectively investigated 46 pediatric liver transplant patients (under 16 years) who survived ≥6 months. The patients were divided into two groups: CHEBV group (EBV DNA >10 000 IU/ml of whole blood for ≥6 months) and nonchronic high EBV (NCHEBV) group (patients who did not meet CHEBV criteria). Tacrolimus was reduced to <3.0 ng/ml in patients with EBV DNA >5000 IU/ml. Blood biochemistry data and pathological findings, obtained at the time of protocol and episodic biopsies, were compared between the two groups. RESULTS: Out of 46 patients, 28 CHEBV and 18 NCHEBV patients were enrolled. The blood biochemical examination did not show a significant difference between the two groups. In addition, no significant differences between the two groups were found in the pathological findings, including frequency of late acute rejection and the progression of fibrosis at the time of both protocol and episodic biopsies. Appropriate adjustment of immunosuppression for CHEBV management may have contributed to the prevention of the progression of fibrosis. CONCLUSION: CHEBV had little adverse effect on the liver graft. Graft fibrosis might have been avoided through optimal dose modification of tacrolimus. Further long-term monitoring is necessary because CHEBV may affect the pediatric liver graft in the long term.

A novel anatomic variation of the intrahepatic biliary tree in live liver donor surgery: A case report.

INTRODUCTION: Anatomic variations of the biliary tree are common, making precise anatomic evaluation important before hepatobiliary surgery. PRESENTATION OF CASE: A 52-year-old woman with no medical history was admitted to our hospital for a live-liver donation to her husband. During her evaluation, magnetic resonance cholangiopancreatography (MRCP) revealed a previously unknown anatomic variation in her biliary system. Segment 2 of the bile duct (B2) independently drained into the posterior branch and formed a common channel (B2+posterior) before joining the anterior branch. Then, bile duct segments 3 and 4 (B3+4) drained into this B2+posterior+anterior channel to form a common hepatic duct. The computerized overlay features shown by MRCP and three-dimensional computed tomography clarified this anatomic variation. A right lobe donor graft was then obtained successfully, with intraoperative cholangiography confirming that the donated graft had two bile duct orifices (i.e., posterior and anterior branches). We thus avoided surgical missteps that would have disallowed bile drainage of B2 and B3+4 into the common hepatic duct. DISCUSSION: Precise evaluation is mandatory for hepatobiliary surgical planning to rule out, or discover, challenging bile duct anatomy. CONCLUSION: Preoperative computerized overlay visualization of MRCP and computed tomography allowed definition of a previously unknown biliary tree variation.

[A Case Report of a Difficult to Diagnose, Extremely Well-Differentiated Stomach Adenocarcinoma Diagnosed by Biopsy].

A Japanese man in his 60s presented with complaints of epigastric pain and weight loss. A gastrointestinal endoscopy revealed multiple gastric ulcers and an irregular mound located on the wall of the lower gastric body along the greater curvature, which was suspected to be cancerous. A biopsy revealed that it was a Group 2 tumor even though the biopsy was repeated 4 times. He was referred to our hospital and 3 biopsies were performed. The final result classified the tumor as Group 4. The patient underwent surgery and the pathological examination revealed an extremely well-differentiated adenocarcinoma( EWDA). An EWDA is characterized by a well-formed mucinous gland with little or no nuclear atypia, which makes preoperative biopsy diagnosis difficult.

Clinical Features and Long-Term Outcomes of Living Donors of Liver Transplantation Who Developed Psychiatric Disorders.

BACKGROUND In the field of living donor liver transplantation (LDLT), it is important to ensure donor's psychological well-being. We report on clinical features and long-term outcomes of LDLT donors who developed psychiatric disorders after their donor operations. Additionally, we compare patient backgrounds, as well as surgical and perioperative aspects between LDLT donors with and without postoperative psychiatric complications. MATERIAL AND METHODS Between November 1998 and March 2018, we identified 254 LDLT donors at our hospital. Among these, we investigated those who had newly developed psychiatric complications and required psychiatric treatment after donor operation. RESULTS The median duration of follow-up was 4 years. Sixty-five donors were lost to follow-up. Eight donors (3.1%) developed postoperative psychiatric complications, including major depressive disorder in 4, panic disorder in 2, conversion disorder and panic disorder in 1, and adjustment disorder in 1. The median duration from donor surgery to psychiatric diagnosis was 104.5 days (range, 12 to 657 days) and the median treatment duration was 18 months (range, 3 to 168 months). Of those, 3 donors required psychiatric treatment over 10 years, and 4 donors remained under treatment. The duration of hospital stay after donor operation was significantly longer and perioperative complications with Clavien classification greater than grade IIIa were more frequent in donors with psychiatric complications than in those without psychiatric complications (P=0.02 and P=0.006, respectively). CONCLUSIONS Accurate diagnosis and appropriate treatment for psychiatric disorders by psychiatrists and psychologists are important during LDLT donor follow-up. Minimization of physiological complications might be important to prevent postoperative psychiatric complications in LDLT donors.

Budd-Chiari Syndrome Associated With Hypereosinophilic Syndrome Treated by Deceased-Donor Liver Transplantation: A Case Report.

INTRODUCTION: Budd-Chiari syndrome (BCS) associated with hypereosinophilic syndrome (HES) is very rare, and only a few reports have described its treatment. Furthermore, no report to date has described the performance of liver transplantation for the treatment of BCS associated with HES. We herein describe a 54-year-old man who underwent deceased-donor liver transplantation (DDLT) for treatment of BCS associated with HES. CASE: A 54-year-old man was found to have an increased eosinophil count during a medical check-up. After exclusion of hematopoietic neoplastic diseases and secondary eosinophilia, idiopathic hypereosinophilia was diagnosed. Oral prednisolone was administered to the patient, and his eosinophil count immediately decreased to a normal level. He had an uneventful course without complications for 11 months but then presented with bloating and malaise. Imaging studies including ultrasonography, enhanced computed tomography, and angiography revealed BCS associated with HES. Transjugular intrahepatic portosystemic shunt failed because of complete obstruction of the hepatic veins. Therefore, the patient was introduced to our hospital for liver transplantation. DDLT was performed with venovenous bypass 1 month after the patient was placed on the DDLT waiting list. The explanted hepatic veins were completely occluded and organized. The patient's eosinophil count was maintained at a normal level with prednisolone treatment after DDLT. CONCLUSIONS: Liver transplantation can be a treatment option for BCS associated with HES if neoplastic diseases and secondary eosinophilia have been excluded. Life-long oral steroid therapy is required to control HES even after liver transplantation.

Early post-operative intravenous tacrolimus in pediatric liver transplant recipients is not superior to oral tacrolimus.

We aimed to compare the early results of i.v. with p.o. TAC as a primary immunosuppressant in pediatric patients undergoing LT. This retrospective study enrolled 75 children who underwent LT and received TAC-steroid regimens as a primary immunosuppressant between September 2011 and October 2015 at our institution. Thirty-five recipients received TAC i.v. and 40 received TAC p.o. Early results were evaluated and compared, including ACR, EBV, or CMV infection; renal adverse effects; and hospital stay. Comparisons of 90-day post-transplant results showed that the rates of overall viral (74% vs 40% P < 0.002), EBV (46% vs 17.5% P < 0.008), and CMV (51% vs 30% P = 0.05) infections were significantly higher in the i.v. than in the p.o. group. Neither regimen has any adverse effects on renal function. There were no between-group differences in ACR incidence and severity, serum creatinine concentration, and hospital stay. Patient and graft survival rates at 3 months and 1 year did not differ significantly between the two groups. Compared with p.o. treatment, i.v. administration of high TAC concentration did not have beneficial post-transplant effects on ACR incidence and severity, while increasing the incidence of viral infections in pediatric LT.

Impact of pretreatments on outcomes after living donor liver transplantation for hepatocellular carcinoma.

BACKGROUND: The purpose of this study was to examine the impact of pretreatments on outcomes after living donor liver transplantation (LDLT) for hepatocellular carcinoma (HCC). METHODS: From February 1999 to March 2015, 223 patients underwent LDLT for HCC. Until December 2006, there was no restriction in patient selection criteria regarding the number and size of tumors, following which we implemented the Kyoto criteria (tumor number ≤10, maximal diameter ≤5 cm, and des-gamma-carboxy prothrombin ≤400 mAU/ml) since January 2007. RESULTS: Of 223 patients, 156 had a history of pretreatments. Among 101 patients meeting the Milan criteria at the initial diagnosis, 38 progressed to beyond the criteria at liver transplantation (LT). Twenty-two out of 38 met the Kyoto criteria, and their survival and recurrence rates were significantly better than those of patients exceeding the Kyoto criteria (P = 0.004 and 0.035, respectively). Regarding the number of pretreatments (0 vs. 1-4 vs. ≥5), recurrence rate was significantly higher in the ≥5 pretreatments group than the 0 group. However, for patients meeting the Kyoto criteria, there were no significant differences in recurrence rates between these three groups. CONCLUSION: Better outcomes will be achieved by performing LT for HCCs meeting the Kyoto criteria even after repeated pretreatments.

Hypoglycemia Unawareness in Insulinoma Revealed with Flash Glucose Monitoring Systems.

The delayed diagnosis of insulinoma remains a clinical issue. One of the main causes of such a delay is hypoglycemia unawareness. A 53-year-old woman fell unconscious during postprandial exercises. Flash glucose monitoring (FGM) systems revealed glucose profiles with fasting hypoglycemia, which facilitated the clinical diagnosis of insulinoma even though she was unaware of her hypoglycemia. The preoperative comparison of the blood glucose values provided by FGM with those obtained from capillary blood were consistent. Thus, FGM may have potential utility in revealing the presence of insulinoma-induced hypoglycemia.

Cytomegalovirus infection in pediatric patients with hepatoblastoma after liver transplantation.

No studies have examined CMV infection in pediatric patients with HB receiving LT. Here, we retrospectively analyzed the incidence of and risk factors for CMV infection in 24 pediatric patients with HB who underwent LT between 1997 and 2015. CMV infection was monitored by measuring expression of pp65 CMV antigen for up to 4 months post-LT. CMV infection, defined as detection of at least one pp65-positive leukocyte, was detected in nine (37.5%) patients who did not develop CMV disease. Nine (47.4%) of nineteen patients who received post-LT chemotherapy experienced CMV infection; however, no CMV infection was observed in the five patients who did not receive post-LT chemotherapy (P = 0.012). There were no significant differences in the incidence of CMV infection between patients with ACR (60.0%) and those without (21.4%, P = 0.092), or between CMV seropositive (55.6%) and seronegative patients (33.3%, P = 0.675). All nine patients with CMV infection did not experience CMV disease due to the use of preemptive antiviral therapy. Close monitoring of CMV infection is recommended for patients with HB, particularly those receiving post-LT chemotherapy. Preemptive antiviral therapy is feasible for prophylaxis of CMV disease.

The Impact of Preoperative Hemoglobin Level on the Short-Term Outcomes After Living Donor Liver Transplantation.

BACKGROUND: Preoperative anemia was reportedly associated with increased morbidity and mortality after various types of surgeries. However, its impact on the outcomes after liver transplantation has not been thoroughly investigated. METHODS: We retrospectively investigated the clinical outcome of 216 consecutive adult patients who underwent living donor liver transplantation at our institute between January 2010 and June 2017 and stratified them according to the hemoglobin level before transplant. Risk factors for 90-day patient mortality, especially infection-related mortality and early graft loss, were evaluated. RESULTS: We found that patients with preoperative hemoglobin below 10 g/dl required more intraoperative packed red blood cell transfusions (p = 0.002) and had significantly higher early 90-day postoperative mortality rate (p = 0.007), particularly infection-related mortality (p = 0.002), lower overall graft, and patient survival rates (p = 0.007, p = 0.013, respectively). Preoperative hemoglobin below 10 g/dl was an independent risk factor for increased post-transplant 90-day patient mortality (OR 2.92, p = 0.02), infection-related mortality (OR 6.81, p = 0.02), and early graft loss (OR 3.26, p = 0.01). CONCLUSION: Preoperative hemoglobin level below 10 g/dl is associated with poorer short-term outcomes after liver transplantation and should be corrected preoperatively if possible through safe and effective treatment modalities.

Prognostic and therapeutic factors influencing the clinical outcome of hepatoblastoma after liver transplantation: A single-institute experience.

LT has contributed to an elevation in cure rates for patients with unresectable HB; however, patients with recurrent HB after LT have poor prognosis. To analyze the prognostic and therapeutic factors that influence the clinical outcome of patients with HB receiving LT, we retrospectively analyzed 24 patients with HB who underwent LT between 1997 and 2015. The 5-year OS rate of all patients was 69.6±9.7%. The 5-year OS rate of 11 patients receiving salvage LT for recurrent tumor after a primary resection was comparable to that of 13 patients receiving primary LT. Among 12 evaluable patients receiving primary LT, six of 10 patients with a decline of serum AFP >95% at LT are currently alive and in remission, whereas two patients with a decline of AFP ≤95% experienced post-LT relapse. Among 9 evaluable patients receiving salvage LT, all three patients with any decline of AFP at LT are currently alive in remission, and three of six patients with no response to pre-LT salvage chemotherapy are also alive and in remission. Response to chemotherapy may be a reliable marker for prediction of post-LT relapse, even for patients receiving salvage LT.

Impact of Donor Age on Recipient Survival in Adult-to-Adult Living-donor Liver Transplantation.

OBJECTIVE: To investigate the influence of donor age on recipient outcome after living-donor partial liver transplantation (LDLT). BACKGROUND: Donor age is a well-known prognostic factor in deceased donor liver transplantation; however, its role in LDLT remains unclear. METHODS: We retrospectively analyzed 315 consecutive cases of primary adult-to-adult LDLT in our center between April 2006 and March 2014. Recipients were divided into 5 groups according to the donor age: D-20s (n = 60); D-30s (n = 72); D-40s (n = 57); D-50s (n = 94); and D-60s (n = 32). The recipient survival and the association with various clinical factors were investigated. RESULTS: Recipient survival proportions were significantly higher in D-20s compared with all the other groups (P = 0.008, < 0.001, < 0.001, and = 0.006, vs D-30s, -40s, -50s, and -60s, respectively), whereas there was no association between recipient survival and their own age. There are 3 typical relationships between donors and recipients in adult-to-adult LDLT: from child-to-parent, between spouses/siblings, and from parent-to-child. The overall survival in child-to-parent was significantly higher than in spouses/siblings (P = 0.002) and in parent-to-child (P = 0.005), despite significantly higher recipient age in child-to-parent [59 (42-69) years, P < 0.001]. Contrastingly, parent-to-child exhibited the lowest survival, despite the youngest recipient age [26 (20-43) years, P < 0.001]. In addition, younger donor age exhibited significantly better recipient survival both in hepatitis C virus-related and in non-hepatitis C virus diseases. Univariate and multivariate analyses both demonstrated that donor age and graft-type (right-sided livers) are independent prognostic factors for recipient survival. CONCLUSIONS: Donor age is an independent, strong prognostic factor in adult-to-adult LDLT.

Clinical application of projection mapping technology for surgical resection of lung metastasis.

Indocyanine green fluorescent image-guided surgery was developed to identify primary and metastatic nodules of various malignancies. However, currently, surgeons need to identify the fluorescent image on a monitor, which impedes surgical procedures. Herein, we developed a novel projection mapping device that can cast the real-time fluorescent image onto the surface of the targeted organ. We performed surgical resection of a lung metastasis of hepatoblastoma using this technique. The projection mapping technique clearly detected the pulmonary lesion, and no other lesions were identified in the ipsilateral thorax. The patient is well and free of recurrence 2 years after surgery.

Portal vein reconstruction using vein grafts in pediatric living donor liver transplantation: Current status.

PV reconstruction is an important aspect of LDLT, with post-transplant outcomes depending on PV reconstruction methods. However, it is unclear whether the preferential selection of these techniques is dependent on preoperative recipient characteristics. This retrospective study assessed whether preoperative recipient factors differed in pediatric patients who did and did not receive VGs for PV reconstruction. Of 113 pediatric patients who underwent LDLT from January 2010 to July 2015, 31 (27%) underwent PV reconstruction with VGs and the other 82 (73%) without VGs. The presence of collateral vessels (P<.0001) and ascites (P=.02); PV size (P<.001), thrombosis (P=.01) and the direction of flow (P=.01), Child-Pugh class A vs B/C liver function (P=.01), Alb concentration (P=.02), primary diagnosis: BA vs non-BA (P=.03), and previous abdominal surgery (P<.005) differed significantly in patients who did and did not receive VGs for PV reconstruction. PV complications, patient survival, and graft survival did not differ significantly in patients with and without VGs at 1-year follow-up. VGs should be harvested for recipients with pretransplant hypoplastic PV, intense collaterals, hepatofugal flow, poor liver status, or previous abdominal surgery.

New-onset diabetes mellitus after living-donor liver transplantation: association with graft synthetic function.

BACKGROUND AND PURPOSE: It is now known that post-transplant graft function after deceased-donor liver transplantation and living-donor liver transplantation (LDLT) differ; however, there is no report assessing the relationship between graft function and the development of new-onset diabetes mellitus after transplantation (NODAT). We conducted this study to identify the predictive risk factors for NODAT, including graft function after LDLT. METHODS: The subjects of this study were 175 adult recipients who underwent LDLT at Kyoto University Hospital between 2006 and 2010, and survived for more than 3 months (median observation period, 1046 days). RESULTS: The 1-, 2-, and 3-year incidences of NODAT after LDLT were 26.1, 32.0, and 33.4%, respectively. Pre-transplant diabetes was associated with poor survival (p = 0.0048), whereas NODAT was not associated with patient survival. In the multivariate analysis, recipient age ≥40, a tacrolimus trough level ≥8 ng/mL 3 months after LDLT, and cholinesterase (ChE) <185 IU/L 3 months after LDLT were the independent risk factors for NODAT. CONCLUSIONS: Poor graft synthetic function 3 months after LDLT as well as older age of the recipient and a higher tacrolimus concentration were strongly associated with NODAT development after LDLT.

p53-independent structure-activity relationships of 3-ring mesogenic compounds' activity as cytotoxic effects against human non-small cell lung cancer lines.

BACKGROUND: We recently demonstrated the cytotoxicity of liquid crystal precursors (hereafter referred to as "mesogenic compounds") in the human non-small cell lung cancer (NSCLC) cell line A549 which carry wild-type p53. p53 mutations are observed in 50 % of NSCLC and contribute to their resistance to chemotherapy. To develop more effective and cancer-specific agents, in this study, we investigated the structure-activity relationships of mesogenic compounds with cytotoxic effects against multiple NSCLC cells. METHODS: The pharmacological effects of mesogenic compounds were examined in human NSCLC cells (A549, LU99, EBC-1, and H1299) and normal WI-38 human fibroblast. Analyses of the cell cycle, cell-death induction, and capsases expression were performed. RESULTS: The 3-ring compounds possessing terminal alkyl and hydroxyl groups (compounds C1-C5) showed cytotoxicity in NSCLC cells regardless of the p53 status. The compounds C1 and C3, which possess a pyrimidine at the center of the core, induced G2/M arrest, while the compounds without a pyrimidine (C2, C4, and C5) caused G1 arrest; all compounds produced caspase-mediated cell death. These events occurred in a p53-independent manner. Furthermore, it was suggested that compounds induced cell death through p53-independent DNA damage-signaling pathway. Compounds C2, C4, and C5 did not show strong cytotoxicity in WI-38 cells, whereas C1 and C3 did. However, the cytotoxicity of compound C1 against WI-38 cells was improved by modulating the terminal alkyl chain lengths of the compound. CONCLUSIONS: We showed the p53-indepdent structure-activity relationships of mesogenic compounds related to the cytotoxic effects. These structure-activity relationships will be helpful in the development of more effective and cancer-specific agents.

How far can we lower graft-to-recipient weight ratio for living donor liver transplantation under modulation of portal venous pressure?

BACKGROUND: Smaller size grafts for living donor liver transplantation (LDLT) can enhance donor safety and expand donor availability. We previously reported that modulation of portal venous pressure (PVP) was key for successful LDLT with small grafts, and that it actively lowered graft-to-recipient weight ratio (GRWR) for adult-to-adult LDLT. This retrospective study investigated the outcome of LDLT using small grafts with PVP modulation. METHOD: This study analyzed 221 adult LDLT patients between March 2008 and December 2013 and divided them into 3 groups based on GRWR: large (L), GRWR ≥ 0.8% (n = 154), medium (M), ≥ 0.7% GRWR < 0.8% (n = 38); and small (S) GRWR < 0.7% (n = 29). Donor and recipient factors, PVP, pressure gradient between PVP and central venous pressure (CVP), occurrence of small for size syndrome (SFSS), ascites, and posttransplant laboratory data were compared across the 3 groups. Patient and graft survival were compared using Kaplan-Meier methods. RESULTS: There was no difference in patient or graft survival between the 3 groups. Amount of posttransplant ascites and posttransplant International Normalized Ratio were similar, but the S and M groups had more prolonged cholestasis. SFSS was identified in 17%, 13%, and 13% in the S, M, and L groups, respectively (P = NS). Patients with a final PVP of ≤15 mmHg had better survival than patients with a final PVP of >15 mmHg (P < .001). Multivariate analysis showed that donor age >40 years old, final PVP of >15 mmHg, and pressure gradient of PVP-CVP >5 mmHg were risk factors for inferior patient survival. CONCLUSION: We achieved satisfactory outcomes in LDLT with GRWR as low as 0.6% using PVP modulation. Thus, we currently set a lower limit of GRWR at 0.6% while protecting donor safety and expanding donor availability.

Liver Transplantation for Non-B and Non-C Hepatocellular Carcinoma.

BACKGROUND/AIMS: Few studies have characterized the outcomes and clinical features of patients who undergo liver transplantation (LT) for hepatocellular carcinoma (HCC) due to non-viral causes. METHODOLOGY: We retrospectively analyzed 188 patients with HCC who underwent LT between February 1999 and October 2010. The clinicopathological factors and overall survival rates as well as recurrence rates of 17 patients with non-hepatitis B virus (HBV) and non-hepatitis C virus (HCV) infection (NBNC group) and 171 patients with HBV or HCV infection (HBV/ HCV group) were compared. RESULTS: HCC patients in the NBNC group were significantly younger at time of transplant, had higher serum des-gamma-carboxy prothrombin levels, and had larger pathological tumor size when compared with patients in the HBV/ HCV group. Overall survival rates were lower, and recurrence rates were higher in the NBNC group than in the HBV/HCV group. However, both these rates were significantly improved in NBNC patients who met our expanded selection criteria when compared with those that did not meet these criteria. CONCLUSIONS: The patients with NBNC HCC had more advanced and biologically aggressive tumors with inferior outcomes when compared with those with HBV/HCV. However, use of appropriate selection criteria for LT yields improved outcomes even in this subgroup of patients.

Impact of preoperative uncontrollable hepatic hydrothorax and massive ascites in adult liver transplantation.

PURPOSE: Uncontrollable hepatic hydrothorax and massive ascites (H&MA) requiring preoperative drainage are sometimes encountered in liver transplantation (LT). We retrospectively analyzed the characteristics of such patients and the impact of H&MA on the postoperative course. METHODS: We evaluated 237 adult patients who underwent LT in our institute between April 2006 and October 2010. RESULTS: Recipients with uncontrollable H&MA (group HA: n = 36) had more intraoperative bleeding, higher Child-Pugh scores, lower serum albumin concentrations and higher blood urea nitrogen concentrations than those without uncontrollable H&MA (group C: n = 201). They were also more likely to have preoperative hepatorenal syndrome and infections. The incidence of postoperative bacteremia was higher (55.6 vs. 46.7%, P = 0.008) and the 1- and 3-year survival rates were lower (1 year: 58.9 vs. 82.9%; 3 years: 58.9 vs. 77.7%; P = 0.003) in group HA than in group C. The multivariate proportional regression analyses revealed that uncontrollable H&MA and the Child-Pugh score were independent risk factors for the postoperative prognosis. CONCLUSIONS: Postoperative infection control may be an important means of improving the outcome for patients with uncontrollable H&MA undergoing LT, and clinicians should strive to perform surgery before H&MA becomes uncontrollable.

Application of complement component 4d immunohistochemistry to ABO-compatible and ABO-incompatible liver transplantation.

Antibody-mediated rejection (AMR) is difficult to diagnose after ABO-compatible or ABO-identical (ABO-C) liver transplantation. To determine whether complement component 4d (C4d) immunostaining would be useful for diagnosing AMR, we compared the results of C4d immunohistochemistry for allograft biopsy samples with assays for anti-donor antibodies performed at the time of biopsy. One hundred fourteen patients with ABO-C grafts and 29 patients with ABO-incompatible (ABO-I) grafts were included. Linear C4d endothelial staining (identifiable with a 4× objective lens) or staining seen in 50% or more of the portal tracts was considered positive. Five of the 114 patients (4%) with ABO-C grafts and 15 of the 29 patients (52%) with ABO-I grafts showed C4d positivity. In the ABO-C cases, C4d positivity in late biopsy samples (≥30 days after transplantation) was associated with stage 2 or higher fibrosis (METAVIR score; P = 0.01) and with the presence of donor-specific anti-human leukocyte antigen DR antibodies (HLA-DR DSAs) with a mean fluorescence intensity > 5000 according to the Luminex single-antigen bead assay (P = 0.04). Conversely, the presence of HLA-DR DSAs was associated with the presence of stage 2 or higher fibrosis, acute cellular rejection, and C4d positivity. During the 2-year follow-up, neither C4d positivity nor HLA-DR DSAs were related to graft loss. Among ABO-I patients, C4d positivity was not associated with allograft dysfunction or fibrosis. Only 3 of the 15 C4d-positive patients (20%) showed periportal hemorrhagic edema, which could be a histological sign of AMR in ABO-I grafts, and they were the only cases associated with elevations in anti-donor A/B antibody titers. In conclusion, C4d endothelial positivity among ABO-C patients is an uncommon event that could be associated with chronic graft damage with or without clinical AMR. C4d positivity is common among ABO-I patients and may not be associated with allograft dysfunction if alloantibody titers are not elevated.