Objective Post-transplant lymphoproliferative disorder （PTLD） is a severe complication following liver transplantation， particularly in pediatric patients， with a high incidence rate associated with EpsteinBarr virus （EBV） infection. The immunological microenvironment of PTLD， particularly the cellular and molecular changes associated with EBV infection， remains unclear. Methods Using single-cell RNA sequencing（scRNAseq）， we examined changes in the immune microenvironment of peripheral blood mononuclear cell（PBMC） from pediatric liver transplant recipients across four groups: PTLD patients with EBV infection， EBV-positive non-PTLD transplant recipients， EBV-negative transplant recipients， and healthy children. Results PTLD patients exhibited profound immune dysregulation， marked by weakened cytotoxicity in NK cells， reduced B cell differentiation and activation， and an inflammatory shift in myeloid cells. EBV infection primarily targeted memory B cells and plasma cells in PTLD patients，with uninfected memory B cells showing impaired functional potential. Furthermore， CD8 + T cells in PTLDwere characterized by increased exhaustion and low cytotoxic activity. In addition， regulatory T cells in PTLD displayed enhanced suppressive functions. Conclusion Our findings present an in-depth view of the immune landscape in PTLD，identifying key immune cell alterations associated with EBV infection and PTLD development. These insights could informthe development of targeted therapies aimed at restoring immune function and controlling EBV-driven lymphoproliferation in pediatric liver transplant recipients.

Objective Split liver transplantation （SLT） is an important innovative technique in transplant surgery that addresses the shortage of donor livers and expands the source of donor organs. Currently， the number of hepatocellular carcinoma patients undergoing SLT is increasing year by year， but its impact on the occurrence of complications and prognosis in hepatocellular carcinoma recipients compared with whole liver transplantation （WLT） remains unclear. This study aims to explore the differences in the occurrence of complications and prognosisbetween WLT and SLT recipients with hepatocellular carcinoma， and to construct a prognostic prediction model forhepatocellular carcinoma recipients underwent SLT by analyzing the prognostic factors. Methods A retrospective selection of 3 773 adult recipients with hepatocellular carcinoma who underwent WLT and SLT registered in the ChinaLiver Transplant Registry （CLTR） from January 2015 to December 2023 was conducted. Clinical data of donors and recipients were collected to compare the clinicopathological characteristics of donors and recipients， the occurrence ofcomplications and prognosis of recipients between the two surgical methods was evaluated. Propensity score matching （PSM） at a 2 ：1 ratio was used to match the baseline clinical data with differences between the WLT and SLT groups，and the incidence of complications and prognosis in the two groups were analyzed. Univariate and multivariate analyses were performed to screen for risk factors related to the prognosis of SLT recipients， and then a prognostic prediction model

was constructed. Results There was no significant difference in the overall survival rate and recurrence-free survival rate between SLT recipients and WLT recipients （P ＞ 0.05）. However， the incidence of postoperative biliary leakage，portal vein embolism， and new-onset diabetes after surgery in SLT recipients were significantly higher than those in theWLT group （postoperative biliary leakage，P ＝ 0.0010 ； portal vein embolism，P ＝ 0.0044 ； new-onset diabetes after surgery，P ＝ 0.036）. Univariate and multivariate analyses of the prognosis of SLT recipients found that donor-recipient

ABO blood type incompatibility， recipient alpha-fetoprotein （AFP）＞ 100 ng/ml， and cumulative tumor diameter ≥ 8 cm were independent risk factors for the prognosis of SLT hepatocellular carcinoma recipients （all P ＜ 0.05）. A prognostic prediction model for SLT recipients was constructed based on the above risk factors， with AUC values of 0.561，0.698， and 0.687 for 1-year，3-year， and 5-year survival rates， respectively. Conclusion The incidence of some postoperative complications in SLT recipients is higher than that in WLT recipients， but the clinical prognosis is similar. Among them，donor-recipient ABO blood type incompatibility， recipient AFP ＞ 100 ng/ml， and cumulative tumor diameter ≥ 8 cm areindependent risk factors affecting the prognosis of SLT hepatocellular carcinoma recipients. The prediction model establishedon this basis has good predictive value for the survival rate of recipients. 

Objective To investigate the clinical efficacy of peptide receptor radionuclide therapy （PRRT）in patients with recurrent neuroendocrine tumors （NETs） after liver transplantation. Methods A retrospective analysis was conducted on the clinical data of 5 patients with recurrent NETs after liver transplantation who underwent PRRT from April 2023 to May 2024 in Tianjin First Central Hospital. Adverse reactions and treatment efficacy were evaluated. Results The median follow-up was 15.6 months. Among the patients，1 achieved partial response （PR），3 had stable disease （SD）， and 1 experienced progressive disease （PD）. Liver function remained stable during treatment， and no rejection reactions occurred. Grade 3 neutropenia was observed in 2 cases， while grade 2 neutropenia occurred in 3 cases. Symptomatic treatment alleviated the condition in 4 cases， but 1 case had persistent severe neutropenia， leading to treatment discontinuation. Grade 1 ～ 2 proteinuria was observed in 2 cases. Conclusion PRRT is safe and effective for patients with recurrent NETs after liver transplantation. The main side effect is neutropenia， and PRRT can be considered as one of the multimodal treatment options. 

Objective To investigate the clinical value of prophylactic contralateral nephroureterectomy in kidney transplant recipients with unilateral upper tract urothelial carcinoma（UTUC） and its impact on prognosis. Methods A retrospective analysis was conducted on clinical data from 49 patients with unilateral UTUC after kidney transplantation at Beijing Friendship Hospital， Capital Medical University between 2002 and 2021. Patients were divided into two groups: the prophylactic group （15 cases undergoing contralateral prophylactic nephroureterectomy） and the non-prophylactic group （34 cases without the procedure）. Overall survival， relapse-free survival， and progressionfree survival were compared between the groups. Multivariable Cox regression analysis was performed to evaluate the independent prognostic significance of prophylactic surgery. Results The baseline characteristics were balanced between the two groups， except that the median time from transplantation to tumor occurrence was significantly shorter in the prophylactic resection group compared to the non-resection group （54 vs. 119 months，P ＝ 0.004）. Survival analysis revealed that the prophylactic resection group exhibited longer median overall survival and progression-free survival than the non-resection group （91 vs. 69.5 months，P ＝ 0.422；69 vs. 31.5 months，P ＝ 0.462）， without statistically significant. However， recurrence-free survival was significantly prolonged in the prophylactic resection group （72 vs. 22 months，P ＝ 0.013）. Multivariate analysis confirmed that prophylactic resection served as an independent protective factor against contralateral urinary tract tumor recurrence （HR＝0.241，95% CI＝0.070～0.825，P＝0.024）. Conclusion Patients with unilateral UTUC after kidney transplantation have an increased risk of contralateral tumor occurrence. Prophylactic contralateral urinary tract resection may facilitate earlier detection of recurrence and progression， potentially improving survival outcomes. Further studies with larger sample sizes are needed to validate these findings. 

Objective To explore the risk factors for developing high-grade urothelial carcinoma in kidney transplant patients with chronic renal insufficiency and progression to uremia after taking traditional Chinese medicine containing aristolochic acid， and to establish its prediction model. Methods A total of 70 patients diagnosed with aristolochic acids nephropathy （AAN） and diagnosed with urothelium carcinoma （UC）after allograft kidney transplantationin Beijing Friendship hospital from January 2003 to January 2025 were included in this study. The patients were divided into high-grade urothelial carcinoma group （HUC group，55 cases in total） and low-grade urothelial carcinoma group （LUC group，15 cases in total） according to their pathological grade. The epidemiological data， general status after transplantation，hydronephrotic conditions and viral infection of patients between the two groups were collected and compared. T test，MannWhitney test and Chi-square test were used to explore the risk factors leading to high-grade urothelial carcinoma， and independent risk factors were analyzed by multiple logistic regression to obtain a prediction model. The accuracy of the prediction model is verified by internal verification. Results There were no statistically significant differences in clinical data such as gender， BMI， previous medical history， estimated glomerular filtration rate （eGFR） at the time of urothelial carcinoma occurrence， thetime from kidney transplantation to the occurrence of urothelial carcinoma， the location of the initial tumor discovery， and the immunosuppressive regimen after transplantation between the HUC group and the LUC group. However， a longer dialysis duration before transplantation， a higher systemic immune inflammatory index （SII） after transplantation， and primary hydronephrosis may all suggest a higher risk of high-grade urothelial carcinoma after transplantation. Multivariate Logistic regression analysis showed that longer dialysis time before transplantation and high SII after transplantation were independent risk factors for highgrade urothelial carcinoma in patients with AAN after transplantation. The probability of disease was 〔-4.89+0.36× pretransplant dialysis time （month） +0.01×SII〕×100%. Internal verification results show that the accuracy of the model is high. Conclusion Early surgery and low SII should be maintained after surgery for kidney transplant patients with chronic renal insufficiency due to previous use of aristolochic acid， to reduce the incidence of high-grade uroepithelial carcinoma after transplantation. 

Objective To analyze the influence of tumor pathological grade on the prognosis of patientswith urothelial carcinoma （UC） after kidney transplantation （KT）. Methods A total of 90 KT recipients whounderwent surgery and were pathologically diagnosed as UC in the Department of Urology， Beijing Friendship Hospital，Capital Medical University from January 1997 to December 2021 were included in this study. The patients' age，gender， time from transplantation to tumor occurrence， immunosuppressant use， tumor location， tumor TNM stage，tumor pathological grade， tumor multiplicity， postoperative survival and recurrence were collected. The patients in this study， the recipients who developed UC after KT were divided into three groups according to the location of the tumor ： non muscle invasive bladder cancer， upper urinary tract urothelial carcinoma， and utuc+ bladder cancer. Eachgroup was divided into high-grade tumor group and non-high-grade tumor group according to the tumor pathological grade of the patients. The main differences in clinical characteristics between the two groups were compared， and then the prognosis of KT recipients between the two groups was analyzed. Results There were 11 cases of non-muscle invasive bladder cancer and 5 cases of high-grade tumor. There were no significant differences in age （P ＝0.081）， gender （P ＝ 0.242）， time from transplantation to tumor occurrence （P ＝ 0.734） and tumor multiplicity （P ＝ 0.545） between high-grade tumor and non-high-grade tumor groups. Only one patient with non-high-grade

tumor died 85 months after the occurrence of tumor， and the rest of the recipients survived during the follow-up period. There were 49 cases of upper urinary tract urothelial carcinoma and 38 cases of high-grade tumor. There were no significant differences in age （P ＝ 0.951）， gender （P = 0.400）， time from transplantation to tumor occurrence （P ＝ 0.206）， tumor multiplicity （P ＝ 0.729）， and T stage （P = 0.073） between the two groups. There were 30 cases of upper urinary tract urothelial carcinoma + bladder cancer at the same time， including 13 cases of high-grade tumors. There were no significant differences in age （P ＝ 0.741）， gender （P ＝ 0.355）， time from transplantation to tumor occurrence（P ＝ 0.783）， and T stage （P ＝ 0.488） between the two groups. The overall survival of patients with high-grade tumors wassignificantly higher than that of patients with non high-grade tumors （P ＝ 0.006）. There was no significant difference inrecurrence between the two groups. Conclusion This study found that high-grade tumor was a high-risk factor affecting the prognosis of KT recipients only when the tumor occurred simultaneously in the bladder and upper urinary tract， while it had little impact on the prognosis of patients when the tumor occurred only in the bladder or upper urinary tract. 

Objective To explore the association between immune therapy and the risk of rejection after liver transplantation in patients with hepatocellular carcinoma （HCC）. Methods A retrospective analysis was conducted on 11 HCC patients who received immune therapy before transplantation at Beijing Friendship Hospital from 2019 to 2025， and 70 cases reported in the literature were included. The incidence of rejection and influencing factors were analyzed. Results The rejection rate in our center's cohort was 9.1% （1/11）， which was lower than that in theneoadjuvant therapy cohort （25.0%）and the post-transplantation cohort （30.8%）in the literature. The rejection rate was significantly reduced when the interval between the last dose of immune therapy and transplantation was more than two halflives. The expression of programmed death ligand 1（PD-L1）in the graft may be related to the risk of rejection and could serve as a potential biomarker for predicting rejection. Conclusion It is recommended to wait at least 8 weeks （two halflives）after immune therapy before liver transplantation. The expression levels of programmed death receptor 1（PD-1）/PDL1 in the graft tissue can be used as potential biomarkers， but further research is needed to explore the mechanism and safe time intervas. 

Objective To investigate the relationship between phase angle（PA） and Z-score values andprognosis in pediatric liver transplant patients. Methods A total of 61 pediatric patients who underwent liver transplantation at Tianjin First Central Hospital from January 2024 to June 2024 were selected for physical examination and bioimpedance analysis （BIA）. Outcome measures included intensive care unit （ICU） length of stay， mechanical ventilation duration， total hospital stay， and postoperative infection status. Results Children in the infection group had significantly lower PA values than those in the non-infection group （P ＜ 0.05）， but there was no significant difference in Z-scores between the two groups. Spearman's correlation analysis was used to assess the correlation between PA， Z-score， and patient outcomes. PA was associated with ICU and hospitalization duration but not with mechanical ventilation duration （r ＝ -0.229，P ＞ 0.05）. Z-score was not significantly associated with prognosis. Conclusion Phase angle measurement can effectively reflect the nutritional status of pediatric patients undergoing liver transplantation and is associated with patient prognosis， demonstrating promising application potential. 

Objective Urological complications such as urinary leakage and ureteral stenosis following transplantation significantly impact the efficacy of renal transplantation surgery. Ureteral stent placement is currently the most common method for reducing ureteral complications; however， the optimal duration for stentindwelling remains controversial. This study aimed to investigate the impact of ureteral stent indwelling time on postoperative outcomes in renal transplant recipients， and to provide clinical evidence for optimal stent removal timing. Methods A prospective cohort study was conducted involving 100 patients who underwent their first allogeneic renal transplantation in Organ Transplant Department，the Second Affiliated Hospital of Guangzhou Medical University between October 2020 and October 2022. Patients were divided into two groups: the stent-on-string group （n ＝ 50）and the conventional stent group （n ＝ 50）. In the stent-on-string group， the stent was removed via the string at 1 week postoperatively. In the conventional stent group， stents were removed via ureteroscopy at 1 month postoperatively. Theincidence of delayed graft function （DGF）， incidence of urological complications， length of hospital stay （LOS）， and renal function during the stable postoperative period were compared between the two groups. Results The stent-on-string group demonstrated a significantly shorter hospital stay and significantly lower incidences of urinary tract infections （UTIs）and BK viremia at 1 month postoperatively compared to the conventional stent group （P ＜ 0.05 for all comparisons）. Conclusion Removal of the ureteral stent at 1 week post-transplantation significantly reduces the incidence of UTIs and BK viremia without increasing the risk of ureteral complications. The use of a stent-on-string avoids patient discomfort which is associated with cystoscopy or ureteroscopy stent removal. Therefore， a stent-on-string should be placed andremoved at 1 week postoperatively when no significant lesions are present in the donor ureter or recipient bladder.