Early chemotherapeutic intervention to avoid thyroidectomy in pediatric Langerhans cell histiocytosis with thyroid involvement accompanying tracheal stenosis: a report of two cases.

Thyroid involvement is rare in pediatric Langerhans cell histiocytosis (LCH). It may cause airway narrowing, leading to acute-onset respiratory distress. Severe cases may require emergent surgical interventions such as thyroidectomy, which should be avoided in children due to higher rates of complication, particularly in infancy. There is currently no consensus on the indications for surgical treatment in LCH with thyroid involvement. In this report, we describe the cases of two children who presented with tracheal stenosis caused by thyroid LCH, both of which were successfully treated by early induction of chemotherapy, and one of which was also treated for a shorter duration. Mutation analysis detected in-frame deletions of BRAF exon 12 in both cases. These cases suggest that timely diagnosis and administration of chemotherapy may alleviate severe airway obstruction and reduce the need for thyroidectomy in pediatric patients with thyroid LCH.

A Japanese retrospective study of non-tuberculous mycobacterial infection in children, adolescents, and young adult patients with hematologic-oncologic diseases.

Non-tuberculous mycobacterial infection (NTM) is rare in healthy children, with lymphadenitis being the most common presentation. Immunocompromised populations are known to be at high risk, but the clinical picture of NTM infection in pediatric hematology/oncology patients is unclear. In this nationwide retrospective analysis of patients under the age of 40 treated in Japanese pediatric hematology/oncology departments who developed NTM infection between January 2010 and December 2020, 36 patients (21 patients with hematopoietic stem cell transplantation (HSCT) and 15 nontransplant patients) were identified. Post-transplant patients were infected with NTM at 24 sites, including the lungs (n = 12), skin and soft tissues (n = 6), bloodstream (n = 4), and others (n = 2). Nine of twelve patients with pulmonary NTM infection had a history of pulmonary graft-versus-host disease (GVHD), and rapid-growing mycobacteria (RGM) were isolated from five of them. In nontransplant patients, the primary diseases were acute lymphoblastic leukemia (ALL; n = 5), inborn errors of immunity (IEI; n = 6), and others (n = 4). All cases of ALL had bloodstream infections with RGM, whereas all cases of IEI were infected with slow-growing mycobacteria (SGM). In summary, three typical clinical scenarios for pediatric hematology/oncology patients have been established: RGM-induced pulmonary disease in patients with pulmonary GVHD, RGM bloodstream infection in patients with ALL, and SGM infection in patients with IEI. Our findings suggest that NTM must be regarded as a pathogen for infections in these high-risk patients, especially those with pulmonary GVHD, who may require active screening for NTM.

Vedolizumab for children with intestinal graft-versus-host disease: a case report and literature review.

Acute graft-versus-host disease (aGVHD) is a challenging complication of allogeneic hematopoietic stem cell transplantation, and alternative therapies for patients showing inadequate response to steroids are limited. Vedolizumab, an anti-α4ß7 integrin antibody widely used for treating inflammatory bowel diseases, has recently been studied in adult patients with steroid-refractory intestinal aGVHD. However, few studies have examined its safety and effectiveness in pediatric patients with intestinal aGVHD. We report the case of a male patient with intestinal late-onset aGVHD treated with vedolizumab. He underwent allogeneic cord blood transplantation for warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome and developed intestinal late-onset aGVHD 31 months after transplantation. The patient was refractory to steroids; however, vedolizumab was initiated 43 months after transplantation (at the age of 7 years) and the symptoms of intestinal aGVHD were alleviated. Additionally, favorable endoscopic findings were observed, such as reduction of erosion and regenerative epithelial growth. We also evaluated the efficacy of vedolizumab in 10 patients with intestinal aGVHD (9 from the literature review and the present case). Six patients (60%) showed an objective response to vedolizumab. No serious adverse events were observed in any patients. Vedolizumab is a potential treatment option for steroid-refractory intestinal aGVHD in pediatric patients.

Human leukocyte antigen 7/8-matched unrelated bone marrow transplantation using anti-thymocyte globulin in children.

Human leukocyte antigen (HLA) mismatched unrelated donor transplantation is associated with an increased risk of graft-versus-host disease, graft failure, and infection, which increases post-transplant morbidity and mortality. In this single-center retrospective study, outcomes were evaluated in 30 consecutive children who underwent bone marrow transplantation (BMT) from HLA 1 allele-mismatched (HLA 7/8-matched) unrelated donors with rabbit anti-thymocyte globulin (rATG) as graft-versus-host disease (GVHD) prophylaxis. The 3-year overall survival (OS), event-free survival (EFS), and GVHD-relapse-free survival rates were 91.7% (95% CI 70.5%-91.9%), 88.3% (95% CI 67.5%-96.1%), and 73.9% (95% CI 52.4%-86.8%), respectively. Grade II-IV and III-IV acute GVHD occurred in 10 (33%) and 2 (7.0%) patients, respectively. The 3-year cumulative incidence of chronic GVHD was 7.8%. No fatal viral infections occurred. The study results show the feasibility of HLA 7/8-matched unrelated BMT with ATG to achieve favorable outcomes and acceptable GVHD, especially for patients who lack a fully matched donor.

Clinical Impact of Melphalan Pharmacokinetics on Transplantation Outcomes in Children Undergoing Hematopoietic Stem Cell Transplantation.

Melphalan is widely used for hematopoietic stem cell transplantation (HSCT) conditioning. However, the relationship between its pharmacokinetic (PK) and transplantation outcomes in children has not been thoroughly investigated. We prospectively analyzed the relationship between melphalan area under the curve (AUC) and transplantation outcome and examined the development of a predictive model for melphalan clearance in children. This study included 43 children aged 0 to 19 years who underwent HSCT following a melphalan-based conditioning regimen from 2017 to 2021. In univariable analysis, high-melphalan AUC resulted in a significantly lower cumulative incidence of acute graft-versus-host disease and a higher cumulative incidence of thrombotic microangiopathy, although no significant difference was observed in survival. Regression analysis of a randomly selected derivation cohort (n = 21) revealed the following covariate PK model: predicted melphalan clearance (mL/min) = 6.47 × 24-h urinary creatinine excretion rate (CER, g/day) × 24-h creatinine clearance rate (CCR, mL/min) + 92.8. In the validation cohort (n = 22), the measured melphalan clearance values were significantly correlated with those calculated based on the prediction equation (R2 = 0.663). These results indicate that melphalan exposure may be optimized by adjusting the melphalan dose according to CER and CCR.

Whole-exome analysis of 177 pediatric patients with undiagnosed diseases.

Recently, whole-exome sequencing (WES) has been used for genetic diagnoses of patients who remain otherwise undiagnosed. WES was performed in 177 Japanese patients with undiagnosed conditions who were referred to the Tokai regional branch of the Initiative on Rare and Undiagnosed Diseases (IRUD) (TOKAI-IRUD). This study included only patients who had not previously received genome-wide testing. Review meetings with specialists in various medical fields were held to evaluate the genetic diagnosis in each case, which was based on the guidelines of the American College of Medical Genetics and Genomics. WES identified diagnostic single-nucleotide variants in 66 patients and copy number variants (CNVs) in 11 patients. Additionally, a patient was diagnosed with Angelman syndrome with a complex clinical phenotype upon detection of a paternally derived uniparental disomy (UPD) [upd(15)pat] wherein the patient carried a homozygous DUOX2 p.E520D variant in the UPD region. Functional analysis confirmed that this DUOX2 variant was a loss-of-function missense substitution and the primary cause of congenital hypothyroidism. A significantly higher proportion of genetic diagnoses was achieved compared to previous reports (44%, 78/177 vs. 24-35%, respectively), probably due to detailed discussions and the higher rate of CNV detection.

Combination chemotherapy consisting of irinotecan, etoposide, and carboplatin for refractory or relapsed neuroblastoma.

BACKGROUND: Patients with primary refractory and relapsed neuroblastoma have a poor prognosis since safe and effective chemotherapies for these patients are currently limited. The development of new chemotherapy regimens for these patients is imperative to improve survival outcomes. METHODS: We retrospectively analyzed 40 patients with refractory (n = 36) or relapsed (n = 4) neuroblastoma who received irinotecan, etoposide, and carboplatin (IREC) as a second-line treatment. We evaluated their therapeutic response and the toxicity of IREC. We also assessed the impact of UGT1A1 gene polymorphisms, which are involved in irinotecan metabolism, on outcomes and toxicity. RESULTS: A total of 112 cycles of IREC were administered to 40 patients with a median of 2 cycles per patient (range, 1-9). Six (15%) patients (UGT1A1 wild-type [n = 2] and heterozygous [n = 4]) showed objective responses, including partial response (n = 1), tumor shrinkage (n = 4), and improved findings on their MIBG scan (n = 1). Grade 4 neutropenia, grade 4 leukopenia, and grades 3-4 gastrointestinal toxicity were observed in 110 (98%), 88 (79%), and 3 (3%) cycles, respectively. There was no IREC-related mortality. Patients with UGT1A1 polymorphisms showed a higher frequency of grade 4 leukopenia, but these patients did not have increased treatment-related mortality or non-hematologic toxicity. CONCLUSIONS: IREC showed an objective response rate of 15% including 1 case with partial response. IREC was well tolerated regardless of UGT1A1 genotype. This study suggests that IREC is a promising second-line chemotherapy for refractory or relapsed neuroblastoma.

Simple and robust methylation test for risk stratification of patients with juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative neoplasm that develops during infancy and early childhood. The array-based international consensus definition of DNA methylation has recently classified patients with JMML into the following 3 groups: high (HM), intermediate (IM), and low methylation (LM). To develop a simple and robust methylation clinical test, 137 patients with JMML were analyzed using the Digital Restriction Enzyme Analysis of Methylation (DREAM), which is a next-generation sequencing-based methylation analysis. Unsupervised consensus clustering of the discovery cohort (n = 99) using DREAM data identified HM (HM_DREAM; n = 35) and LM subgroups (LM_DREAM; n = 64). Of the 98 cases that could be compared with the international consensus classification, 90 HM (n = 30) and LM (n = 60) cases had 100% concordance with DREAM clustering results. Of the remaining 8 cases comprising the IM group, 4 were classified as belonging to the HM_DREAM group and 4 to the LM_DREAM group. A machine-learning classifier was successfully constructed using a support vector machine (SVM), which divided the validation cohort (n = 38) into HM (HM_SVM, n = 18) and LM (LM_SVM; n = 20) groups. Patients with the HM_SVM profile had a significantly poorer 5-year overall survival rate than those with the LM_SVM profile. In conclusion, we developed a robust methylation test using DREAM for patients with JMML. This simple and straightforward test can be easily incorporated into diagnosis to generate a methylation classification for patients so they can receive risk-adapted treatment in the context of future clinical trials.

Successful treatment of a novel type I interferonopathy due to a de novo PSMB9 gene mutation with a Janus kinase inhibitor.

BACKGROUND: Type I interferonopathies are a recently established subgroup of autoinflammatory diseases caused by mutations in genes associated with proteasome degradation or cytoplasmic RNA- and DNA-sensing pathways. OBJECTIVE: This study aimed to unveil the molecular pathogenesis of a patient with novel type I interferonopathy, for which no known genetic mutations have been identified. METHODS: We performed the whole-exome sequencing of a 1-month-old boy with novel type I interferonopathy. We also investigated proteasome activities using patient-derived B lymphoblastoid cell lines (LCLs) and normal LCLs transduced with the mutant gene. RESULTS: Whole-exome sequencing identified a de novo proteasome 20S subunit beta 9 (PSMB9) p.G156D mutation in the patient who developed fever, a chilblain-like skin rash, myositis, and severe pulmonary hypertension due to the hyperactivation of IFN-α. Patient-derived LCLs revealed reduced proteasome activities, and exogenous transduction of mutant PSMB9 p.G156D into normal LCLs significantly suppressed proteasome activities, and the endogenous PSMB9 protein was lost along with the reduction of other immunoproteasome subunits, PSMB8 and PSMB10 proteins. He responded to the administration of a Janus kinase inhibitor, tofacitinib, and he was successfully withdrawn from venoarterial extracorporeal membranous oxygenation. At age 7 months, he received an unrelated cord blood transplantation. At 2 years posttransplantation, he no longer required tofacitinib and experienced no disease recurrence. CONCLUSIONS: We present the case of a patient with a novel type I interferonopathy caused by a de novo PSMB9 p.G156D mutation that suppressed the wild-type PSMB9 protein expression. Janus kinase inhibitor and stem cell transplantation could be curative therapies in patients with severe interferonopathies.

The eldest case of MICPCH with CASK mutation exhibiting gross motor regression.

BACKGROUND: MICPCH is manifested as microcephaly associated with pontocerebellar hypoplasia and global developmental delay but developmental regression has never been reported. We describe the detailed clinical history of a woman with intellectual disability and microcephaly with pontine and cerebellar hypoplasia (MICPCH) with a CASK mutation who exhibited gross motor regression after adolescence. CASE: The patient experienced severe motor and intellectual developmental delay with microcephaly from infancy. The initial diagnosis was Rett syndrome based on her clinical features, including hand stereotypes and the absence of structural abnormality on magnetic resonance imaging (MRI) performed at the age of 5 years. Although gross motor abilities developed slowly and she could walk independently, she never acquired speech or understanding of languages. After adolescence, her motor ability gradually regressed so that she was unable to stand without support and moved with a wheelchair. At the age of 31 years, because of her atypical clinical course for Rett syndrome, whole exome sequencing was performed, which revealed a de novo heterozygous c.2068 + 1G > A mutation in the CASK gene (NM_001126055). Brain MRI revealed mild pontocerebellar hypoplasia compatible with the clinical phenotype of MICPCH. DISCUSSION: This case suggests that MICPCH with a CASK mutation might cause developmental regression after adolescence and might be regarded as a neurodegenerative disorder.

Comparison of high-dose and low-dose corticosteroid therapy for refractory Mycoplasma pneumoniae pneumonia in children.

BACKGROUND: Mycoplasma pneumoniae pneumonia (MPP) is generally a self-limiting disease, but it may become refractory. It is thought that refractory MPP is linked to the excessive immunologic responses of the host. Consequently, the use of adjunctive systemic corticosteroids may have beneficial effects. In this study, we compared the effects of high- and low-dose corticosteroid therapy in a pediatric population with refractory MPP. METHODS: We retrospectively collected data from 91 pediatric MPP patients treated with adjunctive systemic corticosteroids between April 2014 and October 2016. The patients were divided into the following two groups: high-dose corticosteroid group (2 mg/kg/day or more of prednisolone equivalents; n = 38) and low-dose corticosteroid group (<2 mg/kg/day; n = 53). Additionally, we compared the number of febrile days post-corticosteroid administration. We used 25 paired patients in a propensity score matching analysis to correct for confounding factors both by age and by days (from onset till corticosteroid therapy initiation). RESULTS: We observed that in the high-dose corticosteroid group defervescence following corticosteroid therapy initiation was achieved significantly earlier and length of hospitalization was significantly shorter (0.8 ± 1.0 vs. 1.5 ± 1.4 days and 8.2 ± 2.4 vs. 10.7 ± 2.7 days, respectively). In the propensity score matching, we observed that significant differences in the length of fever following corticosteroid therapy initiation and hospitalization were still present. Further, neither of the groups developed corticosteroid-related adverse events. CONCLUSION: Our results suggest that patients with refractory MPP treated with high-dose corticosteroid could achieve defervescence earlier and have a shorter hospitalization.

Allogeneic stem cell transplantation with reduced intensity conditioning for patients with adrenoleukodystrophy.

OBJECTIVE: The prognosis of adrenoleukodystrophy (ALD)with neurological involvement is generally dismal; however, allogeneic stem cell transplantation (SCT) is recognized as effective to stabilize or improve the clinical symptoms of ALD. Herein, we report the clinical outcomes of patients with ALD who consecutively underwent allogeneic stem cell transplantation with reduced intensity conditioning at our institution. PATIENTS: Sixteen patients with ALD, who were symptomatic (n = 14) or presymptomatic (n = 2), received SCT from 2010 to 2016. The stem cell source was cord blood (n = 14), or bone marrow from a human leukocyte antigen identical sibling (n = 2). The conditioning regimen prior to transplantation was reduced intensity and consisted of fludarabine (125 mg/m2), melphalan (140 mg/m2) and low dose total body irradiation (TBI) of 4Gy (n = 15) or 3Gy (n = 1). RESULTS: Primary engraftment was obtained in 11 patients, and 4 of the 5 patients who lost the primary graft received a second cord blood transplantation and were engrafted. Five years overall and event-free survival were 90.9% and 61.1% respectively, with a median of 45 months (range 16-91). Loes score stabilized or improved by 18 months after transplantation except for patients with internal capsule involvement. CONCLUSION: Allogeneic SCT with reduced intensity conditioning for patients with ALD was safely performed without major transplant-related complications even in symptomatic patients and neurological symptoms were stabilized after SCT in patients without internal capsule involvement.

MEF2D-BCL9 Fusion Gene Is Associated With High-Risk Acute B-Cell Precursor Lymphoblastic Leukemia in Adolescents.

PURPOSE: Acute lymphoblastic leukemia (ALL) makes up a significant proportion of all pediatric cancers, and relapsed ALL is a leading cause of cancer-associated deaths in children. Identification of risk factors and druggable molecular targets in ALL can lead to a better stratification of treatments and subsequent improvement in prognosis. PATIENTS AND METHODS: We enrolled 59 children with relapsed or primary refractory ALL who were treated in our institutions. We primarily performed RNA sequencing (RNA-seq) using patients' leukemic cells to comprehensively detect gene fusions and analyze gene expression profiles. On the basis of results obtained by RNA-seq, we performed genetic validation, functional analysis, and in vitro drug sensitivity testing using patients' samples and an exogenous expression model. RESULTS: We identified a total of 26 gene fusions in 22 patients by RNA-seq. Among these, 19 were nonrandom gene fusions already described in ALL, and four of the remaining seven involved identical combination of MEF2D and BCL9. All MEF2D-BCL9-positive patients had B-cell precursor immunophenotype and were characterized as being older in age, being resistant to chemotherapy, having very early relapse, and having leukemic blasts that mimic morphologically mature B-cell leukemia with markedly high expression of HDAC9. Exogenous expression of MEF2D-BCL9 in a B-cell precursor ALL cell line promoted cell growth, increased HDAC9 expression, and induced resistance to dexamethasone. Using a primary culture of leukemic blasts from a patient, we identified several molecular targeted drugs that conferred inhibitory effects in vitro. CONCLUSION: A novel MEF2D-BCL9 fusion we identified characterizes a novel subset of pediatric ALL, predicts poor prognosis, and may be a candidate for novel molecular targeting.

Recurrent bacteremia with different strains of Streptococcus pyogenes in an immunocompromised child.

We report an immunocompromised child who experienced two episodes of bacteremia due to Streptococcus pyogenes. Random amplification of polymorphic DNA profiles, emm genotypes, superantigen profiles, antimicrobial susceptibility, and resistance-related genes were investigated, and the results showed different profiles between the two isolates. This is the first report describing recurrent bacteremia caused by different strains of S. pyogenes.