Is primary hepatic angiosarcoma in children an indication for liver transplantation?-A single-centre experience and review of the literature

Role of mTOR Inhibitors in Pediatric Liver Transplant Recipients: A Systematic Review

BACKGROUND

Immunosuppressive medications play a crucial role in determining both organ and patient survival following liver transplantation (LT). Typically, immunosuppressive protocols for pediatric LT patients rely on calcineurin inhibitors (CNIs). While inhibitors of mammalian target of rapamycin (mTOR) have demonstrated beneficial outcomes in adult recipients of liver allografts, such as improved renal function post-LT, their application in pediatric liver transplant recipients is a subject of debate due to uncertain efficacy and potential adverse effects.

OBJECTIVES

This review evaluates the potential roles of mTOR inhibitors in the context of pediatric LT patients.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for conduct and reporting. Databases until 31 August 2023 were searched using specific terms and keywords. All clinical studies focusing on mTOR inhibitors in pediatric LT were included.

RESULTS

Out of 888 identified articles, 30 studies, involving 386 children who had undergone liver transplantation and received mTOR-inhibitor-based immunosuppressive regimens, met the inclusion criteria. The beneficial impacts of switching from a CNI to an mTOR inhibitor or adding an mTOR inhibitor to CNI-reduced immunosuppression in LT pediatric patients with impaired kidney function are controversial, and high-powered clinical studies are need. It appears that enhancing immunosuppression by adding an mTOR inhibitor to CNI is helpful for pediatric LT recipients who are experiencing refractory acute rejection or chronic rejection. mTOR-inhibitor-containing regimens failed to reduce the occurrence of post-transplant lymphoproliferative disorders (PTLD) among children with LT that may be due to concomitant high CNI concentration among studied patients. The effectiveness of mTOR inhibitors in treating PTLD remains uncertain; however, in patients with PTLD who are at high risk of rejection, mTOR inhibitors may be administered. Conversion to or the addition of mTOR inhibitors to maintenance immunosuppression seems to be suitable for pediatric patients who received a transplant due to hepatic malignancies such as hepatoblastoma or hepatocellular carcinoma or for those with post-transplant primary or recurrent malignancies. Switching to an mTOR inhibitor may improve some CNI-related adverse effects such as gingival hyperplasia, neurotoxicity, nephropathy, hypertrophic cardiomyopathy, or thrombotic microangiopathy.

CONCLUSION

Although the exact role of mTOR inhibitors among pediatric patients who have received a liver transplant needs further study, two algorithms are presented in this review to guide conversion from CNIs to mTOR inhibitors or the addition of mTOR inhibitor to a CNI-minimization immunosuppressive regimen for pediatric patients who may benefit from this class of drugs. This review mainly consisted of retrospective studies with inadequate sample sizes and lacked a control group, which represents the main limitation of this study.

Pediatric Angiosarcoma with Novel Phenotypic and Genotypic Profile in Chinese Children

Introduction: Angiosarcoma is an exceedingly rare entity in pediatric population. Herein, we report two pediatric angiosarcoma with novel phenotypic and genotypic profile. Methods: The two patients' information was summarized by clinical data, histopathology, immunohistochemistry, genetic, treatment, and prognosis. Results: Two Chinese children presented with abdominal mass or consumptive hypothyroidism at 2 and 6 years. A patient presented with a unique histopathology of epithelioid AS with smooth muscle hyperplasia, and carried a novel somatic mutation in FAT1 (c.3929C > T/p. Ser1310Leu) along with germ-line variants in CDK8 (c.895A > C/p. Lys299Gln), FANCI (c.3906-07inv/p. Glu1303Lys), and MST1R (c.3581-83delinsACG/p. Arg1194-Ser1195delinsHisGly). The other patient presented with a novel -clinical phenotype of consumptive hypothyroidism. They received postoperative treatment and were monitored for 20 and 26 months, showing good recovery. Conclusion: The phenotypic and genotypic spectrum of AS in pediatric population was expanded by these two patients, which requires the accumulating more cases to gain a deeper understanding.

Liver transplantation for pediatric liver malignancies

In the last few decades, collaboration between international pediatric oncology groups has resulted in significant improvement in survival after liver transplantation (LT) for pediatric liver tumors, and LT has become the accepted standard of care for unresectable pediatric liver tumors-either living donor liver transplantation or deceased donor liver transplantation. Hepatoblastoma and HCC are the common pediatric liver malignancies treated by LT, and LT is now the accepted treatment modality for unresectable nonmetastatic cases. The long-term survival rate is more than 80% in hepatoblastoma transplants. Furthermore, with the advent of living donor liver transplantation, the waitlist mortality, availability of a better graft quality with shorter ischemic times, and performance of LT with the appropriate timing between chemotherapy have all improved. Up to 80% of pediatric HCCs are unresectable, and studies have shown that LT for pediatric HCC has better outcomes than liver resection. Furthermore, LT has also shown better results than liver resection for cases of HCC not meeting Milan criteria. Given the rarity of pediatric liver malignancies and challenges in optimal management, a multidisciplinary treatment approach, research models building on what is already known, and consideration of newer treatment modalities are required for further improving the treatment of pediatric liver malignancies.

The role of liver transplantation in the care of primary hepatic vascular tumours in children

Liver transplantation (LT) is the standard of care for many liver conditions, such as end-stage liver diseases, inherited metabolic disorders, and primary liver malignancies. In the latter group, indications of LT for hepatoblastoma and hepatocellular carcinoma evolved and are currently available for many non-resectable cases. However, selection criteria apply, as the absence of active metastases. Evidence of good long-term outcomes has validated the LT approach for managing these malignancies in the context of specialist and multidisciplinary approach. Nevertheless, LT's role in treating primary vascular tumours of the liver in children, both benign and malignant, remains somewhat controversial. The rarity of the different diseases and the heterogeneity of pathological definitions contribute to the controversy and make evaluating the benefit/risk ratio and outcomes quite difficult. In this narrative review, we give an overview of primary vascular tumours of the liver in children, the possible indications and the outcomes of LT.

Not only a small liver - The pathologist's perspective in the pediatric liver transplant setting

Pediatric liver transplantation represents a safe and long-lasting treatment option for various disease types, requiring the pathologist's input. Indeed, an accurate and timely diagnosis is crucial in reporting and grading native liver diseases, evaluating donor liver eligibility and identifying signs of organ injury in the post-transplant follow-up. However, as the procedure is more frequently and widely performed, deceptive and unexplored histopathologic features have emerged with relevant consequences on patient management, particularly when dealing with long-term treatment and weaning of immunosuppression. In this complex and challenging scenario, this review aims to depict the most relevant histopathologic conditions which could be encountered in pediatric liver transplantation. We will tackle the conditions representing the main indications for transplantation in childhood as well as the complications burdening the post-transplant phases, either immunologically (i.e., rejection) or non-immunologically mediated. Lastly, we hope to provide concise, yet significant, suggestions related to innovative pathology techniques in pediatric liver transplantation.