Abstract: Introduction: Germ cell tumors (GCT) encompass a wide variety of neoplasms with varying clinical behavior dependent on histology, staging, and site. GCT remain relatively uncommon in the pediatric population and most patients have a favorable prognosis. However, the well-established co-occurrence of primary mediastinal GCT (PMGCT) and acute myeloid leukemia (AML) has a dismal prognosis with few reported patients achieving sustained remission. Case presentation: An 18 y.o. male was concurrently diagnosed with PMGCT and AML, type M7. Cytogenetic analysis revealed a complex set of chromosomal alterations along with homozygous deletion of TP53. His concurrent oncologic processes were managed with a variety of chemotherapy regimens, complete surgical resection of the mediastinal mass, and hematopoietic stem cell transplant (HSCT). He is one of few patients with concurrent PMGCT and AML able to achieve remission with no evidence of disease nearly 5 years after completion of treatment. Conclusion: The rare, but well-identified, association between PMGCT and concurrent or subsequent AML has a dismal prognosis. Modern genetics sequencing has identified common aberrations, including i(12p), trisomy/tetrasomy 8, TP53, and PTEN mutations. With this knowledge, it may allow for future tailoring of therapy to improve the predicted outcome of patients with PMGCT and AML.

Retinoblastoma, the most common intraocular tumor in childhood, still faces challenges in diagnosis and treatment, particularly in low- and middle-income countries. Identifying strategies to improve the time to diagnosis and access to treatment is crucial to enhance survival rates and preserve ocular health. We conducted a systematic review to identify interventions that have demonstrated potential in addressing these challenges. We performed a comprehensive search across databases until March 2023. Out of the studies reviewed, twenty-one met the inclusion criteria and were categorized into five main areas: surveillance strategies, genetic counseling, education, public assistance and international partnership. Despite the obstacles faced, the initiatives identified in this review present acts towards improving the time to diagnosis and access to treatment for retinoblastoma. Based on the extracted data, we propose a comprehensive chain of initiatives. We firmly believe that implementing this chain of initiatives can lead to improved clinical outcomes for retinoblastoma patients.

Secondary histiocytoses are exceedingly rare and knowledge about pathophysiology and treatment is limited. We report the first known case of Philadelphia chromosome -like - B-lymphoblastic leukemia complicated by disseminated juvenile xanthogranuloma in an adolescent salvaged successfully with targeted MEK inhibition.

Here, we describe two patients with juvenile xanthogranuloma (JXG) manifesting with Langerhans cell histiocytosis-associated neurodegenerative disease (ND)-like radiological findings. One patient showed typical radiological abnormalities at onset, which worsened with progressing central nervous system symptoms 7 years after LCH-oriented chemotherapy. Another showed spontaneous regression of clinical symptoms, with a transient radiological change 1 year after salvage chemotherapy for recurrence of JXG. These data regarding JXG-associated ND will facilitate future investigation of the disease, as well as development of therapeutic interventions.

Title : Evans syndrome in the background of 22q11.2 deletion syndrome

Background: The outcome of extramedullary infiltration (EMI) in pediatric acute myeloid leukemia (AML) is controversial, and little is known about the implications of stem cell transplantation (SCT) and gemtuzumab ozogamicin (GO) treatment on AML patients with EMI. Methods: We retrieved the clinical data of 713 pediatric AML patients from the TARGET dataset and analyzed the clinical and prognostic characteristics of patients with EMI at initial diagnosis and relapse. Results: A total of 123 patients were identified to have EMI at initial diagnosis and 64 presented with EMI at relapse. We discovered that the presence of EMI was associated with age ≤2 years, M5 morphology, abnormal karyotype, and KMT2A rearrangements. Hyperleukocytosis and complex karyotype were more prevalent in EMI relapse patients. Additionally, patients with EMI at diagnosis showed a reduced incidence of FLT3 ITD-/NPM1+, whereas EMI relapse patients displayed a lower frequency of FLT3 ITD+. Patients with EMI at diagnosis exhibited a lower rate of CR1 and higher incidence of relapse. Importantly, EMI at diagnosis independently predicted both shorter EFS and OS. Regarding relapse patients, the occurrence of EMI at relapse showed no impact on OS. However, relapse patients with myeloid sarcoma exhibited a poorer OS compared to those with exclusive CNS involvement. Furthermore, in reference to patients with EMI at initial diagnosis, SCT failed to improve the survival, whereas GO treatment may potentially enhance OS. Conclusion: EMI at initial diagnosis is an independent prognostic risk factor, GO treatment has the potential to improve survival for patients with EMI at diagnosis.

The low incidence of vincristine-induced peripheral neuropathy (VIPN) in Kenyan children may result from low vincristine exposure. We performed a pharmacokinetically (PK) guided dose-escalation feasibility study of vincristine in Kenyan children (NCT05844670). Vincristine PK exposure was assessed with a previously developed nomogram. A 20% dose increase was recommended for participants with low exposure and no VIPN, hyperbilirubinemia or malnutrition. None of the fifteen participants developed VIPN. Low vincristine exposure was seen in only one participant: a dose increase was implemented without side-effects. Average vincristine exposure was high. In conclusion, the participants did not develop VIPN despite having high vincristine exposure.

An 11-year-old boy with Lowe syndrome developed secondary sexual characteristics within a few weeks, suggestive of precocious puberty. His blood tests were positive for serum-human chorionic gonadotropin, and imaging revealed a right thymic lobe mass containing small cystic lesions. A germ cell tumor with malignant potential was suspected. Thus, we performed an extended thymectomy with mediastinal lymph node dissection and confirmed germinoma of the right thymic lobe without lymph node metastasis; the patient underwent four courses of chemotherapy. Follow-up evaluations indicated no recurrence. Thus, we present a highly rare case report of thymic germinoma complicated by Lowe syndrome.

POLE codes for DNA polymerase epsilon (Pol ε) and variants of Pol ε catalytic subunit 1 can be pathogenic. We recently reported a novel POLE gene variant (p.[D1131fs];[T1891del]) which leads to bone marrow failure in two Japanese sisters. Here, we describe the successful course of hematopoietic stem cell transplantation of these two sisters. Both cases were born with congenital anemia and remained transfusion dependent. Their bone marrow showed gradually proceeding trilineage dysplasia. They both underwent HCT from an unrelated bone marrow donor and successfully achieved engraftment. Ten and eight years have passed respectively, and they are doing well without transfusion.

The AYA gap for rhabdomyosarcomaSimone Hettmer1 and Lars H. Lindner2Division of Pediatric Hematology and Oncology, Department of Pediatric and Adolescent Medicine, University Medical Center Freiburg, University of Freiburg, Freiburg, Germany.Department of Medicine III, LMU University Hospital, LMU Munich, Marchioninistr. 15, 81377, Munich, Germany.To whom correspondence should be addressed. Email: [email protected]. Phone: +49 761 270-45140; Fax: +49 761 270-4518Cancer is the leading cause of death among adolescents and young adults (AYAs). Cancers diagnosed during the AYA period - defined by the National Cancer Institute as the age from 15 to 39 years - account for approximately 5% of all cancers [1]. As per the national report on the status of cancer (study period 2015-2019, [1]), 5-year relative survival rates for both children and AYAs suffering from cancer are high (85.1% for children and 85.8% for AYAs), and improvements in survival over time appear to be similar for both age groups [1]. Yet, the spectrum of cancer types diagnosed in AYAs varies widely. The most common malignancies are female breast cancer (15%), thyroid cancer (15%), testicular cancer (8%) and melanomas (7%) [1], but AYAs may also suffer from so-called pediatric cancers with peak incidence during childhood. When compared to their childhood counterparts, worse outcomes were reported for AYAs diagnosed with pediatric cancers, including but not limited to leukemias [2] and sarcomas [3]. This „AYA gap“ is of concern to both pediatric and adult oncologists.The accompanying paper by Harrison et al examines a cohort of 2151 patients with rhabdomyosarcomas (RMS) enrolled in consecutive Children’s Oncology Group (COG) trials, including 19% AYAs aged 15-39 years and 81% children aged 0-14 years [4]. Compared to children with RMS, AYAs experienced significantly lower 5-year event-free survival (EFS; 44% vs. 67%) and 5-year overall survival (OS; 52% vs. 78%). These observations are in line with a recent retrospective analysis of nearly 2000 patients treated on European paediatric Soft Tissue Sarcoma Group (EpSSG) protocols [3]. Importantly, relative survival of AYAs with RMS treated on EpSSG and COG protocols appears to be better [3, 4] than the survival observed in epidemiological studies such as EUROCARE-5 (39,6% 5-year relative survival among RMS patients aged 15–19 years, and 36·4% for those aged 20–39 years; study period 2000-2007 [5]). Survival benefits for AYA patients treated on pediatric RMS protocols are consistent with previous observations in AYAs receiving treatment according to pediatric acute lymphoblastic leukemia (ALL) protocols [2] or at pediatric cancer centers/ sites with pediatric oncology expertise [6]. AYA cancer patients appear to benefit from chemotherapy dose intensities higher than what is generally prescribed to older patients. They may also draw advantages from pediatric standards with respect to planning of multimodal treatment and cancer staging. For example, the bone marrow (rarely ever involved in adult-type soft tissue sarcomas (STS)) is the most frequent site of metastases in AYAs with RMS treated within the COG cohort reported by Harrison et al [4] and should always be considered when planning pre-treatment examinations of AYAs with RMS. All taken together, adult oncology providers of AYA patients with RMS are well advised to consult their pediatric oncology colleagues and/ or consider referral to an institution with pediatric oncology expertise.AYA cancer patients treated on pediatric protocols – including those suffering from RMS - still experience worse outcomes than their pediatric counterparts [2]. There is ample evidence to support higher risk biology, more aggressive clinical phenotypes and higher rates of early treatment failures in AYAs diagnosed with pediatric cancers – including leukemias andsarcomas- compared to children diagnosed with the same malignancies [2-4]. For RMS tumors, higher rates of alveolar histology tumors and metastatic disease in AYAs were observed in the COG cohort reported here [4], as well as in the EpSSG and other retrospective studies [3, 7]. In addition to higher-risk disease manifestation, more frequent treatment-related toxicities and higher rates of withdrawal from treatment contribute to worse outcomes of AYAs compared to children with cancer [2]. There is a direct association between age and treatment-related deaths for patients undergoing ALL treatment on pediatric protocols [2]. Harrison et al do not comment on differences in treatment-related toxicities between children and AYAs with RMS, but higher rates of vincristine neurotoxicity, nausea and pain were previously reported in older adolescents undergoing RMS treatment on pediatric protocols. Even in the absence of higher-grade toxicities, a high burden of low-grade adverse events can have a major impact on the ability to function in daily life, continue education, maintain employment or participate in social activities. Many AYAs with cancer need to rely more on their parents/ support persons, which threatens their age-appropriate strive for autonomy and may result in them rebelling against treatment recommendations or failing to self- manage complex medication plans [8]. Active involvement of AYAs in the development of a care plan, which considers dignity, normalcy and family/ social relationships may improve compliance and, ultimately, treatment success.RMS is the most common STS in children and adolescents and often referred to as a pediatric cancer. Nevertheless, it occurs at any age, and up to 40% of all cases are diagnosed in adults (including seniors) [9]. The molecular and histological heterogeneity of pediatric RMS was studied intensively in recent years [10]. However, the insights provided by Harrison et al [4] and Ferrrai et al [3] emphasize that the remarkable diversity apparent across the RMS spectrum is multidimensional. Distinct clinical and biological characteristics of RMS diagnosed in different age groups deserve further attention. The two main pediatric RMS subtypes are embryonal and alveolar RMS, whereas pleomorphic RMS and RMS not otherwise specified are predominant in older adults and considered fundamentally different cancers [9]. To obtain a better understanding of RMS diagnosed in AYAs, future study efforts should aim at investigating the full spectrum of the disease and differentially consider the molecular underpinnings and therapeutic requirements of RMS diagnosed at opposite ends of the AYA age range.

Objective (69) The occurrence of unpredictable pain crises are the principal determinant of the quality of life for patients with venous malformations (VM). A definite coagulation phenomenon, characterized by an increase in D-dimer levels and the presence of phleboliths within the malformation, has been previously reported. By applying Virchow’s triad and evaluating intralesional samples, our objective is to delineate the coagulation profile and the extent of endothelial dysfunction within the malformation. Methods (42) With the authorization of the Ethics Committee, a research project was undertaken on intralesional and extralesional blood samples from 30 pediatric patients afflicted with spongiform VM. Thromboelastometry analyses were performed using ROTEM ® Sigma, and the concentration of syndecan-1 was determined by ELISA. Results (80) In the ROTEM ® analyses, the A5, A10, and MCF values were below the established reference ranges in the intralesional samples in both the EXTEM and INTEM assays indicating that intralesional clots had significant instability. Furthermore, during the investigation of the delayed fibrinolysis phase using recombinant tissue plasminogen activator (rtPA) in EXTEM analysis, widespread hyperfibrinolysis was observed intralesional. Additionally, analysis of syndecan-1 showed significant differences between extralesional and intralesional levels (p<0.026) and controls (p<0.03), suggesting differences in the state of endothelium. Conclusions (39) For the first time, we developed a comprehensive understanding of the coagulopathic profile of VM and the role of endothelial dysfunction in its pathogenesis. These findings will enable the implementation of targeted therapies based on the individual coagulation profiles.

Regression of kaposiform lymphangiomatosis and chronic disseminated intravascular coagulation after inhaled budesonide-formoterol treatmentMasaru Imamura1, Chansu Shin1, Akihiko Saitoh1, Michio Ozeki 2, Kentaro Matsuoka3 Chihaya Imai11Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan2Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan3Department of Pathology, Tokyo Metropolitan Children’s Medical Center, Tokyo, JapanCorresponding author: Masaru Imamura, Department of Pediatrics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuou-ku, Niigata City, Niigata 951-8510, Japan.Phone +81-25-227-2222FAX +81-25-227-0778Email: [email protected] Count for Main Text: 701 wordsNumber of Tables: 0Number of Figures: 2Running title: KLA IMPROVED AFTER INHALED STEROIDKeywords: kaposiform lymphangiomatosis, lymphatic malformation, inhaled corticosteroid, rare disease, progressive diseaseAbbreviations:

Adeeb Oweidat MD, DESAIC, EDRA

Treatment for childhood solid tumors may lead to an increased risk for gonadal dysfunction/infertility. Discussion of risk should occur at diagnosis, any changes in therapy, and during survivorship. Gonadotoxic therapies were abstracted from 32 Children’s Oncology Group (COG) phase III, frontline solid tumor protocols, in use from 2000-2022. Risk for gonadal dysfunction/infertility was assessed based on gonadotoxic therapies, sex, and pubertal status and assigned as minimal, significant, and high following the Oncofertility Consortium Pediatric Initiative Network (PIN) risk stratification. Most protocols (65.6%, 21/32) contained at least one therapeutic arm with a high level of increased risk. Solid tumor therapies present challenges in risk stratification due to response-adjusted therapy and the need to account for radiation field in the risk assessment. This guide hopes to serve as a tool to assist in standardizing gonadotoxic risk assessments across disciplines and improve referral for fertility services and reproductive health counseling for patients receiving COG based solid tumor therapy.

OBJECTIVES In the etiology of childhood cancers, many genetic and environmental factors play a role. One of these factors is cigarette smoking and the main source of tobacco smoke exposure of children is parental smoking. However, establishing a causal relationship between parental smoking and childhood cancers has proven challenging due to difficulties in accurately detecting tobacco smoke exposure METHODS To address this issue, we used hair cotinine analysis and a questionnaire to get information about tobacco smoke exposures of pediatric cancer patients and healthy children. 104 pediatric cancer patients and 99 healthy children participated in our study. Parental smoking behaviours (pre-conceptional, during pregnancy and current smoking) and environmental tobacco smoke (ETS) exposures of children are compared. RESULTS We have found no differences between two groups by means of maternal smoking behaviours. However, the rates of paternal pre-conceptional smoking and smoking during pregnancy were significantly low in cancer patients (p<0,05). These data suggests that social desirability bias among fathers of cancer patients may have contributed to this discrepancy. According to questionnaire cancer patients had significantly lower ETS exposures than healthy children (p<0,05). However, ETS exposure assessment through cotinine analysis demonstrated that cancer patients had higher exposure to ETS compared to healthy children (p<0.001). CONCLUSION Our findings provide evidence supporting the potential role of smoking as a risk factor for childhood cancers. This study also revealed that questionnaires could cause biases. We suggest that cotinine analysis along with validated questionnaires can be used to prevent biases in studies of tobacco smoke in the etiology of childhood cancers.

Background: Recent data found a correlation between lymphopenia occurring early during craniospinal irradiation (CSI) and risk of disease recurrence in newly-diagnosed childhood medulloblastoma. 1 However, the population included patients that received myelosuppressive chemotherapy prior to or during RT. Here we investigate the effect of lymphopenia during RT in patients with newly-diagnosed pediatric medulloblastoma who did not receive myelosuppressive chemotherapy with RT. Procedure: We analyzed 54 patients with newly-diagnosed medulloblastoma (ages 2-21 years) treated between 1997-2013 with CSI. Log-rank tests were used to determine survival differences, and Cox proportional hazards regression was used to assess associations between patient characteristics and lymphopenia with disease recurrence risk. Results: 78% of patients (40/51) had grade ≥3 lymphopenia by RT week 3; 49% (23/47) improved to grade ≤2 lymphopenia by week 5. Similarly, the lowest median absolute lymphocyte count (ALC) occurred during RT week 3. Sixteen of 54 (30%) patients recurred an average of 30.2 months post-diagnosis. There was higher risk of disease recurrence in patients with grade ≥3 lymphopenia during weeks 4 (log-rank p=0.015; Cox p=0.03) and 5 (log-rank p=0.0009; Cox p=0.004) of RT. Recurrence-free survival was lower in patients with ALC Conclusions: Lymphopenia during RT weeks 4 and 5 correlates with increased risk of tumor recurrence in pediatric patients with newly-diagnosed medulloblastoma. Future studies should correlate baseline numbers of tumor-infiltrating lymphocytes with risks of lymphopenia during RT and tumor recurrence.

Background: There remains limited knowledge about the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-COV2) vaccination in pediatric oncology patients, which is essential to provide counseling and risk adaptation in this vulnerable population. The goal of this study was to understand immunogenicity after vaccination in pediatric oncology patients and determine if certain clinical factors impacted response. Methods: Patients 0-25 years of age with a diagnosis of cancer and actively receiving therapy were enrolled on study. We excluded patients who were completely vaccinated prior to their cancer diagnosis. Blood samples were collected pre-vaccination, as well as 2, 4-6, and 8-12 weeks after vaccination. Healthy children who were fully vaccinated enrolled as controls. Clinical data and complete blood counts around time of vaccination were collected. To study B and T cell immunity, we measured neutralizing antibodies by enzyme-linked immunoassay and interferon gamma secretion by enzyme-linked immunospot, respectively. Results: 26 patients enrolled on study, for which 11 were evaluable oncology patients and 7 were healthy controls. Adequate B cell response was seen in 36.4% of patients and adequate T cell response in 77.8% of patients. Numbers were too small to detect differences based on malignancy type. There was no differences in immunity based on absolute lymphocyte count (ALC) or intensity of therapy. Conclusion: Pediatric oncology patients have a suboptimal immune response to SARS-COV2 vaccination. Booster doses will be imperative to provide optimal protection against COVID-19, however blood counts may not be a useful guide to optimize the time of administration.

Background and Objectives: Initially developed as immunosuppressive agents, mTOR inhibitors are currently used widely in the management of vascular malformations and tumors. The incidence of infectious complications in the vascular anomalies (VA) population is not well defined. The goal of this systematic review was to better define the types and severity of reported infectious complications in patients with VAs treated with mTOR inhibition. Methods: This was a systematic review conducted following PRISMA guidelines evaluating all research articles focused on infectious complications in patients with VAs treated with sirolimus or everolimus. Thirty articles including 1181 total patients and 315 infections (in 290 unique patients) were ultimately included. Results: The majority of infections were viral upper respiratory (n=137, 54%), followed by pneumonia (n=52, 20%), and cutaneous infections (n=20, 8%). There were 6 total infection-related fatalities, which all occurred in patients younger than 2 years. Only 1 case of Pneumocystis jirovecii pneumonia (PJP) was reported. This was in an infant with KHE who was also treated with steroids and did not receive PJP prophylaxis. Almost 1/3 (n=95, 32%) of infectious complications were graded 3 to 4 according to CTCAE criteria. Details of patient age, subtype of VA, and timing of infection were lacking from many reports. Conclusions: Most infectious complications reported in patients with VA on mTOR inhibitors were viral respiratory infections and non-severe. Bacteremia, infectious fatalities, and PJP are exceedingly rare. Future studies are needed to clarify the spectrum of infectious risks in VA patients and to provide guidance for infection prevention.