Background Accurate risk stratification of Langerhans cell histiocytosis (LCH) is essential as management can range from conservative in single system, low risk for central nervous system (CNS) involvement lesions to intensive chemotherapy for multisystem or high‐risk disease. Additionally, being able to differentiate metabolically active from inactive lesions is essential for both prognostic reasons and to avoid potentially unnecessary treatment. Methods A retrospective review was performed on all patients with histopathology‐confirmed LCH at Cincinnati Children's Hospital Medical Center (CCHMC) between 2009 and 2019. Results One hundred seven positron emission tomography (PET)/computerized tomography (CT) images were included in the review. A discrepancy between PET/CT and conventional imaging occurred on 53 occasions. On 13 occasions, increased uptake was observed on PET in an area with no identifiable lesion on conventional imaging. On 40 occasions, lesions were found on conventional imaging where no increased uptake was observed on PET. On eight skeletal surveys, three other radiographs, four diagnostic CTs, five localization CTs, and one bone scan, no lesion was identified in an area with increased fluorodeoxyglucose (FDG) uptake. This occurred exclusively in bone. On nine skeletal surveys, one other radiograph, four diagnostic CTs, six localization CTs, 19 magnetic resonance imaging (MRI) scans, and one bone scan, a lesion was identified in a location without increased FDG uptake. This occurred in bone, CNS, and lungs. Conclusion F‐18‐FDG PET/CT is vital in the evaluation of LCH lesions given its ability to detect LCH lesions not detectable on conventional imaging modalities, as well as its ability to distinguish metabolically active from inactive disease. MRI and diagnostic CT are still useful adjunctive tests for identification of CNS and lung lesions.

Background Pediatric hematology/oncology (PHO) patients receiving therapy or undergoing hematopoietic stem cell transplantation (HSCT) often require a central line and are at risk for bloodstream infections (BSI). There are limited data describing outcomes of BSI in PHO and HSCT patients. Methods This is a multicenter (n = 17) retrospective analysis of outcomes of patients who developed a BSI. Centers involved participated in a quality improvement collaborative referred to as the Childhood Cancer and Blood Disorder Network within the Children's Hospital Association. The main outcome measures were all‐cause mortality at 3, 10, and 30 days after positive culture date; transfer to the intensive care unit (ICU) within 48 hours of positive culture; and central line removal within seven days of the positive blood culture. Results Nine hundred fifty‐seven BSI were included in the analysis. Three hundred fifty‐four BSI (37%) were associated with at least one adverse outcome. All‐cause mortality was 1% (n = 9), 3% (n = 26), and 6% (n = 57) at 3, 10, and 30 days after BSI, respectively. In the 165 BSI (17%) associated with admission to the ICU, the median ICU stay was four days (IQR 2‐10). Twenty‐one percent of all infections (n = 203) were associated with central line removal within seven days of positive blood culture. Conclusions BSI in PHO and HSCT patients are associated with adverse outcomes. These data will assist in defining the impact of BSI in this population and demonstrate the need for quality improvement and research efforts to decrease them.

Infections with double stranded DNA viruses are a significant cause of morbidity and mortality in pediatric patients following allogeneic hematopoietic stem cell transplantation (HSCT). Virus specific T-cell therapy (VSTs) have been shown to be effective treatment for infections with adenovirus, BK virus, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). To date, prophylactic regimens to prevent or mitigate these infections using conventional anti-viral medications provide suboptimal response rates. Here we report on a clinical trial (NCT03883906) performed to assess the feasibility of rapid manufacturing and early infusion of quadrivalent VSTs generated from stem cell donors ("donor derived VSTs") into allogeneic HSCT recipients with minimal or absent viremia. Patients were eligible to receive scheduled VSTs as early as twenty-one days after stem cell infusion. Twenty-three patients received scheduled VSTs. 20/23 had no viremia at the time of infusion while three patients had very low-level BK viremia. Two developed clinically significant graft-versus-host disease, although this incidence was not outside of expected incidence early after HSCT and both were successfully treated with systemic corticosteroids (n=2). Five patients were deemed treatment failures. Three developed subsequent significant viremia/viral disease (n=3). Eighteen patients did not fail treatment, seven of whom did not develop any viremia while 11 developed low-level, self-limited viremia that resolved without further intervention. No infusion reactions occurred. In conclusion, scheduled VSTs appear to be safe and potentially effective at limiting serious complications from viral infections after allogeneic transplantation. A randomized study comparing this scheduled approach to the use of VSTs to treat active viremia is ongoing.