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Currently, there is no consensus among pediatric kidney transplant centers regarding the use and regimen for immunosuppressive induction therapy.In this single center, retrospective cohort study, pediatric kidney transplant recipients transplanted between 1 May 2013 and 1 May 2018 with rabbit antithymocyte globulin (rATG) induction were included. We stratified patients based on immunological risk, with high risk defined as those with repeat transplant, preformed donor specific antibody, current panel-reactive antibodies 20%, 0 antigen match and/or African-American heritage. Outcome of interest was the incidence of biopsy proven acute rejection by 1 year.A total of 166 patients met inclusion criteria. Age of patients was 12 years (11 mo-21 y), (median, range), 21.5% received a living donor transplant and 50.6% were female. Low-immunologic-risk patients were divided into 2 groups, those who received the lower cumulative rATG dose of ≤ 3.5 mg/kg (n = 52) versus the higher cumulative dose of 3.5 mg/kg (n = 47). The median total dose in the lower dose group was 3.1 (IQR 0.3) and 4.4 (IQR 0.8) in the higher dose group, P 0.001. Rejection rate did not differ significantly between the 2 treatment groups (7/52 vs. 6/47). None in the lower dose group developed BK nephropathy versus 3 in the higher dose group. Graft loss due to BK nephropathy occurred in 1 patient in the higher dose group. Graft loss in the whole cohort at 12 months was a rare event (n = 1) with 99.5% graft survival and 100% patient survival.Reduced rATG dosing (≤ 3.5 mg/kg) when compared to higher dosing ( 3.5 mg/kg) is safe and effective in low-risk pediatric kidney transplant recipients without increasing risk of rejection. A higher resolution version of the Graphical abstract is available as Supplementary information.

PURPOSE: To evaluate whether ultrasmall superparamagnetic iron oxide nanoparticle (USPIO)-enhanced magnetic resonance imaging (MRI) can detect allograft rejection in pediatric kidney transplant patients. PROCEDURES: The USPIO ferumoxytol has a long blood half-life and is phagocytosed by macrophages. In an IRB-approved single-center prospective clinical trial, 26 pediatric patients and adolescents (age 10–26 years) with acute allograft rejection (n = 5), non-rejecting allografts (n = 13), and normal native kidneys (n = 8) underwent multi-echo T2* fast spoiled gradient-echo (FSPGR) MRI after intravenous injection (p.i.) of 5 mg Fe/kg ferumoxytol. T2* relaxation times at 4 h p.i. (perfusion phase) and more than 20 h p.i. (macrophage phase) were compared with biopsy results. The presence of rejection was assessed using the Banff criteria, and the prevalence of macrophages on CD163 immunostains was determined based on a semi-quantitative scoring system. MRI and histology data were compared among patient groups using t tests, analysis of variance, and regression analyses with a significance threshold of p < 0.05. RESULTS: At 4 h p.i., mean T2* values were 6.6 ± 1.5 ms for native kidneys and 3.9 ms for one allograft undergoing acute immune rejection. Surprisingly, at 20–24 h p.i., one rejecting allograft showed significantly prolonged T2* relaxation times (37.0 ms) compared to native kidneys (6.3 ± 1.7 ms) and non-rejecting allografts (7.6 ± 0.1 ms). Likewise, three additional rejecting allografts showed significantly prolonged T2* relaxation times compared to non-rejecting allografts at later post-contrast time points, 25–97 h p.i. (p = 0.008). Histological analysis revealed edema and compressed microvessels in biopsies of rejecting allografts. Allografts with and without rejection showed insignificant differences in macrophage content on histopathology (p = 0.44). CONCLUSION: After ferumoxytol administration, renal allografts undergoing acute rejection show prolonged T2* values compared to non-rejecting allografts. Since histology revealed no significant differences in macrophage content, the increasing T2* value is likely due to the combined effect of reduced perfusion and increased edema in rejecting allografts.

Atypical hemolytic uremic syndrome (aHUS) evolves into end-stage renal failure in nearly half of affected patients and is associated with defective regulation of the alternative complement pathway. Patients with a complement factor H (CFH) mutation have a 30-100% risk of graft loss due to aHUS recurrence or graft thrombosis. Since CFH is produced predominantly by the liver, combined liver-kidney transplant is a curative treatment option. One major unexpected risk includes liver failure secondary to uncontrolled complement activation. We report a successful combined liver-kidney transplantation with perioperative plasma exchange and use of the humanized anti-C5 monoclonal antibody eculizumab.An 11-month-old female presented with oliguric renal failure after 3 weeks of flu-like symptoms in the absence of diarrhea. Following the identification of Escherichia coli 0157:H7 in her stool, she was discharged home on peritoneal dialysis with a diagnosis of Shiga toxin-associated HUS. Three months later, she developed severe anemia, thrombocytopenia, and neurological involvement. aHUS was diagnosed and confirmed, and genetic testing revealed a mutation in CFH SCR20. Once donor organs became available, she received preoperative plasma exchange followed by eculizumab infusion with intra-operative fresh frozen plasma prior to combined liver-kidney transplant. At 19 months post-transplant, she continues to have excellent allograft and liver function without signs of disease recurrence.Perioperative use of eculizumab in conjunction with plasma exchange during simultaneous liver-kidney transplant can be used to inhibit terminal complement activity, thereby optimizing successful transplantation by reducing the risk of graft thrombosis.

Undifferentiated embryonal sarcoma is the third most common malignant tumor of the liver in children, accounting for 13% of hepatic malignancies in this age group. It has been considered an aggressive neoplasm with very poor prognosis until the late 1980s, when long-term survivors were reported after multiagent chemotherapy followed by resection. We, herein, report two pediatric cases of undifferentiated embryonal sarcoma treated successfully with surgical resection after neoadjuvant chemotherapy based on therapy used in childhood soft tissue sarcomas and in childhood hepatic malignancies. The first patient also had a concurrent cerebellar tumor (pilocytic astrocytoma), for which he first underwent craniotomy and resection, delaying the liver tumor resection by 10 weeks. They are alive and tumor free at 48 months (case no. 1) and 18 months (case no. 2) following neoadjuvant chemotherapy and liver resection.

Recent advancements in liver transplantationhave resulted in extended survival both for grafts andrecipients. Such improvement, together with the shortageof donor organs has prompted expansion of the donor pool to include less than ideal donors,especially in life-threatening situations. The use ofolder liver donors has been associated with lowerlong-term survival. However, potential morbidity such as gallstone formation has not been explored.We analyzed bile composition in a child who developedcholesterol gallstones in the proximal bile duct twoyears after undergoing emergency liver transplantation with a liver from a 78-year-old donor. Oraladministration of ursodeoxycholic acid (ursodiol)shifted the cholesterol composition of the bile from asupersaturated, potentially crystallized state to aliquid (micellar) state. Unlike cyclosporin A, FK506showed an increase in the proportion of chenodeoxycholicacid and a decrease in the proportion of cholic acid,and thus may exhibit minimal or no hepatotoxic effect. Thus, in donor livers with factorsknown to be associated with cholesterol gallstoneformation (such as age, sex, or obesity), one mayconsider analyzing the bile composition at the time ofprocurement. Depending on cholesterol and bile acidcomposition, the use of FK506 with or without additionof ursodeoxycholic acid may be warranted.