Pediatric Hemophagocytic Lymphohistiocytosis: Formation of an Interdisciplinary HLH Working Group at a Single Institution.

Fever of unknown origin is a common presentation in children with an extensive differential diagnosis that encompasses multiple specialties. From a hematologic standpoint, the differential includes hyperinflammatory syndrome, such as hemophagocytic lymphohistiocytosis (HLH), among others. Due to the rarity of HLH and nonspecific symptoms at initial presentation, specialists are often consulted later in the disease progression, which complicates disease evaluation further. Cook Children's Medical Center (CCMC) has recently developed a multidisciplinary histiocytic disorder group that is often consulted on cases presenting with fever of unknown origin to increase awareness and potentially not miss new HLH cases. In this study, we examine the clinical presentation and workup of 13 patients consulted by the HLH work group at a single institution and describe the clinical course of 2 patients diagnosed with HLH. The goal of this project was to describe the formation of a disease-specific team and the development of a stepwise diagnostic approach to HLH. A review of the current diagnostic criteria for HLH may be warranted given findings of markers such as soluble IL2 receptor and ferritin as nonspecific and spanning multiple disciplines including rheumatology, infectious disease, and hematology/oncology.

Implementing a Disease-specific Multidisciplinary Team and Order Set for Hemophagocytic Lymphohistiocytosis in a Pediatric Hospital.

OBJECTIVE: To improve outcomes of hemophagocytic lymphohistiocytosis (HLH), prompt recognition and treatment are necessary. A HLH multidisciplinary team was implemented at our institution, and we established an electronic order set to foster uniformity in the diagnostic approach. The goal of this study is to capture the impact of this diagnostic tool. METHODS: This is a retrospective study analyzing the utilization of a HLH-specific order set since time of implementation in June 2019 through December 2022. The trends in the utilization of the order set by providers were analyzed to evaluate the awareness and effectiveness of this tool. RESULTS: The order set was utilized 50 times, most commonly by hematology/oncology (50%) and infectious disease (26%). Utilization by providers on newly presenting patients included 4 times in the year 2019, 12 times in 2020, 16 times in 2021, and 18 times in 2022. Utilization was associated with the diagnosis of HLH in 9 patients (18%). CONCLUSION: Implementation of an HLH-specific order set facilitated a systematic method to approach patients with suspected HLH. The utilization of the order set displayed an upward trend over time, indicating support of this tool among these providers. This tool can increase awareness and early identification of HLH.

Augmentation of umbilical cord blood (UCB) transplantation with ex vivo-expanded UCB cells: results of a phase 1 trial using the AastromReplicell System.

Allogeneic stem cell transplantation with umbilical cord blood (UCB) cells is limited by the cell dose a single unit provides recipients. Ex vivo expansion is one strategy to increase the number of cells available for transplantation. Aastrom Biosciences developed an automated continuous perfusion culture device for expansion of hematopoietic stem cells (HSCs). Cells are expanded in media supplemented with fetal bovine serum, horse serum, PIXY321, flt-3 ligand, and erythropoietin. We performed a phase 1 trial augmenting conventional UCB transplants with ex vivo-expanded cells. The 28 patients were enrolled on the trial between October 8, 1997 and September 30, 1998. UCB cells were expanded in the device, then administered as a boost to the conventional graft on posttransplantation day 12. While expansion of total cells and colony-forming units (CFUs) occurred in all cases, the magnitude of expansion varied considerably. The median fold increase was 2.4 (range, 1.0-8.5) in nucleated cells, 82 (range, 4.6-266.4) in CFU granulocyte-macrophages, and 0.5 (range, 0.09-2.45) in CD34+ lineage negative (lin-) cells. CD3+ cells did not expand under these conditions. Clinical-scale ex vivo expansion of UCB is feasible, and the administration of ex vivo-expanded cells is well tolerated. Augmentation of UCB transplants with ex vivo-expanded cells did not alter the time to myeloid, erythroid, or platelet engraftment in 21 evaluable patients. Recipients of ex vivo-expanded cells continue to have durable engraftment with a median follow-up of 47 months (range, 41-51 months). A randomized phase 2 study will determine whether augmenting UCB transplants with ex vivo-expanded UCB cells is beneficial.