L3MBTL2 maintains MYCN-amplified neuroblastoma cell proliferation through silencing NRIP3 and BRME1 genes.

Epigenetic alterations critically affect tumor development. Polycomb-group complexes constitute an evolutionarily conserved epigenetic machinery that regulates stem cell fate and development. They are implicated in tumorigenesis, primarily via histone modification. Polycomb repressive complex 1 (PRC1) complexes 1-6 (PRC1.1-6) mediate the ubiquitination of histone H2A on lysine 119 (H2AK119ub). Here, we studied the functional roles of a PRC1.6 molecule, L3MBTL2, in neuroblastoma (NB) cells. L3MBTL2-knockout and knockdown revealed that L3MBTL2 depletion suppressed NB cell proliferation via cell-cycle arrest and gamma-H2A.X upregulation. L3MBTL2-knockout profoundly suppressed xenograft tumor formation. Transcriptome analysis revealed suppressed cell-cycle-related and activated differentiation-related pathways. Break repair meiotic recombinase recruitment factor 1 (BRME1) and nuclear receptor interacting protein 3 (NRIP3) were notably de-repressed by L3MBTL2-knockout. The deletion of L3MBTL2 reduced enrichment of H2AK119ub and PCGF6 at transcriptional start site proximal regions of the targets. Add-back studies unveiled the importance of L3MBTL2-BRME1 and -NRIP3 axes for NB cell proliferation. We further manifested the association of MYCN with de-repression of NRIP3 in an L3MBTL2-deficient context. Therefore, this study first revealed the significance of L3MBTL2-mediated gene silencing in MYCN-amplified NB cells.

Results of the JRS-I LRA0401 and LRB0402 Japan Rhabdomyosarcoma Study Group trials for low-risk embryonal rhabdomyosarcoma.

BACKGROUND: Failure-free survival (FFS) rates of low-risk patients with rhabdomyosarcoma improved in Intergroup Rhabdomyosarcoma Study IV after the escalation of cyclophosphamide total dose to 26.4 g/m2. However, this dose may increase the risk of adverse events, including infertility, in some patients. The JRS-I LRA0401 and LRB0402 protocols aimed to reduce the cyclophosphamide dose to 9.6 g/m2 and 17.6 g/m2, respectively, without decreasing the FFS rates. METHODS: Subgroup-A patients received eight cycles (24 weeks) of vincristine, actinomycin D, and 1.2 g/m2/cycle cyclophosphamide. Subgroup-B patients received eight cycles (24 weeks) of vincristine, actinomycin D, and 2.2 g/m2/cycle cyclophosphamide, followed by six cycles (24 weeks) of vincristine and actinomycin D. Group II/III patients in both subgroups received radiotherapy. RESULTS: In subgroup A (n = 12), the 3-year FFS rate was 83% (95% confidence interval [CI], 48-96), and the 3-year overall survival (OS) rate was 100%. Only one isolated local recurrence was observed (8.3%). There were no unexpected grade-4 toxicities and no deaths. In subgroup B (n = 16), the 3-year FFS and OS rates were 88% (95% CI, 59-97) and 94% (95% CI, 63-99), respectively. There were no unexpected grade 4 toxicities and no deaths. CONCLUSIONS: Shorter duration therapy using vincristine, actinomycin D, and lower dose cyclophosphamide with or without radiotherapy for patients with low-risk subgroup A rhabdomyosarcoma (JRS-I LRA0401 protocol) and moderate reduction of cyclophosphamide dose for patients with low-risk subgroup B rhabdomyosarcoma (JRS-I LRB0402 protocol) did not compromise FFS.

Phase II study in children and adults under 40 years with newly diagnosed Langerhans cell histiocytosis: protocol for an LCH-19-MSMFB clinical trial in Japan.

INTRODUCTION: Although the prognosis of Langerhans cell histiocytosis (LCH) is excellent, the high recurrence rate and permanent consequences, such as central diabetes insipidus and LCH-associated neurodegenerative diseases, remain to be resolved. Based on previous reports that patients with high-risk multisystem LCH show elevated levels of inflammatory molecules, we hypothesised that dexamethasone would more effectively suppress LCH-associated inflammation, especially in the central nervous system (CNS). We further hypothesised that intrathecal chemotherapy would effectively reduce CNS complications. We administer zoledronate to patients with multifocal bone LCH based on an efficacy report from a small case series. METHODS AND ANALYSIS: This phase II study (labelled the LCH-19-MSMFB study) is designed to evaluate the significance of introducing dexamethasone and intrathecal chemotherapy for multisystem disease and zoledronate for multifocal bone disease in previously untreated, newly diagnosed children, adolescents (under 20 years) and adults under 40 years. The primary endpoint is the 3-year event-free survival rate by risk group of under 20 years and the 3-year event-free survival rate of 20 years and over. ETHICS AND DISSEMINATION: This study was approved by the Central Review Board of the National Hospital Organisation Nagoya Medical Centre (Nagoya, Japan) on 21 January 2022 and was registered in the Japan Registry of Clinical Trials (https://jrct.niph.go.jp/en-latest-detail/jRCTs041210027). Written informed consent will be obtained from all patients and/or their guardians. TRIAL REGISTRATION NUMBER: jRCTs041210027.

Impact of gallbladder hypoplasia on hilar hepatic ducts in biliary atresia.

BACKGROUND: Biliary atresia (BA) is an intractable disease of unknown cause that develops in the neonatal period. It causes jaundice and liver damage due to the destruction of extrahepatic biliary tracts,. We have found that heterozygous knockout mice of the SRY related HMG-box 17 (Sox17) gene, a master regulator of stem/progenitor cells in the gallbladder wall, exhibit a condition like BA. However, the precise contribution of hypoplastic gallbladder wall to the pathogenesis of hepatobiliary disease in Sox17 heterozygous embryos and human BA remains unclear. METHODS: We employed cholangiography and histological analyses in the mouse BA model. Furthermore, we conducted a retrospective analysis of human BA. RESULTS: We show that gallbladder wall hypoplasia causes abnormal multiple connections between the hilar hepatic bile ducts and the gallbladder-cystic duct in Sox17 heterozygous embryos. These multiple hilar extrahepatic ducts fuse with the developing intrahepatic duct walls and pull them out of the liver parenchyma, resulting in abnormal intrahepatic duct network and severe cholestasis. In human BA with gallbladder wall hypoplasia (i.e., abnormally reduced expression of SOX17), we also identify a strong association between reduced gallbladder width (a morphometric parameter indicating gallbladder wall hypoplasia) and severe liver injury at the time of the Kasai surgery, like the Sox17-mutant mouse model. CONCLUSIONS: Together with the close correlation between gallbladder wall hypoplasia and liver damage in both mouse and human cases, these findings provide an insight into the critical role of SOX17-positive gallbladder walls in establishing functional bile duct networks in the hepatic hilus of neonates.

Biliary atresia (BA) is a disease in newborns that causes a serious liver condition due to damage to the bile ducts (the pathways that carry bile juice). Although reduced function of a key gene called Sox17, which is essential for forming the gallbladder wall, has been observed in some BA cases, the link between gallbladder issues and liver damage is unknown. This study has shown how damage spreads through the bile ducts in the liver around the time of birth when there are problems in the gallbladder wall due to reduced SOX17 function. The findings indicate that proper growth of the gallbladder wall during this critical period is essential for forming a normal network of bile ducts in the developing liver. This discovery is promising for early diagnosis and better treatment of BA in newborns.

A nationwide phase II study of delayed local treatment for children with high-risk neuroblastoma: The Japan Children's Cancer Group Neuroblastoma Committee Trial JN-H-11.

PURPOSE: Survival rates of patients with high-risk neuroblastoma are unacceptable. A time-intensified treatment strategy with delayed local treatment to control systemic diseases has been developed in Japan. We conducted a nationwide, prospective, single-arm clinical trial with delayed local treatment. This study evaluated the safety and efficacy of delayed surgery to increase treatment intensity. PATIENTS AND METHODS: Seventy-five patients with high-risk neuroblastoma were enrolled in this study between May 2011 and September 2015. Delayed local treatment consisted of five courses of induction chemotherapy (cisplatin, pirarubicin, vincristine, and cyclophosphamide) and myeloablative high-dose chemotherapy (melphalan, etoposide, and carboplatin), followed by local tumor extirpation with surgery and irradiation. The primary endpoint was progression-free survival (PFS). The secondary endpoints were overall survival (OS), response rate, adverse events, and surgical complications. RESULTS: Seventy-five patients were enrolled, and 64 were evaluable (stage 3, n = 8; stage 4, n = 56). The estimated 3-year PFS and OS rates (95% confidence interval [CI]) were 44.4% [31.8%-56.3%] and 80.7% [68.5%-88.5%], resspectively. The response rate of INRC after completion of the treatment protocol was 66% (42/64; 95% CI: 53%-77%; 23 CR [complete response], 10 VGPR [very good partial response], and nine PR [partial response]). None of the patients died during the protocol treatment or within 30 days of completion. Grade 4 adverse effects, excluding hematological adverse effects, occurred in 48% of patients [31/64; 95% CI: 36%-61%]. Major Surgical complications were observed in 25% of patients [13/51; 95% CI: 14%-40%]. CONCLUSION: This study indicates that delayed local treatment is feasible and shows promising efficacy, suggesting that this treatment should be considered further in a comparative study of high-risk neuroblastoma.

Rituximab-combined anthracycline-free chemotherapy in newly diagnosed paediatric and adolescent patients with non-high-risk aggressive mature B cell lymphoma: protocol for a single-arm, open-label, multicentre, phase II study (the Japan Children's Cancer Group Multicentre Trial, JPLSG B-NHL-20).

INTRODUCTION: Children and adolescents with mature B cell non-Hodgkin lymphoma (B-NHL) are treated with short-intensive chemotherapy. The burden of short-term and long-term toxicity is highly relative to its high cure rate in good-risk patients. Although the addition of rituximab to standard lymphome Malin B (LMB) chemotherapy markedly prolongs event-free survival and overall survival in high-risk patients, the benefit of rituximab in good-risk patients remains to be elucidated. This clinical trial will examine whether the addition of rituximab eliminates anthracyclines in good-risk patients without compromising treatment outcomes. METHODS AND ANALYSIS: We will perform a single-arm, open-label, multicentre phase II study. Low-risk (stage I - completely resected, stage II abdominal) and intermediate-risk (stages I and II - incompletely resected; stage II - resected, other than abdominal; stage III with LDH <2× upper limit of normal) patients with newly diagnosed B-NHL are eligible. Low-risk patients receive two courses of R-COM1P (rituximab, cyclophosphamide, vincristine, methotrexate, prednisolone and intrathecal methotrexate with hydrocortisone), and intermediate-risk patients receive COP (cyclophosphamide, vincristine, prednisolone and intrathecal methotrexate with hydrocortisone) followed by two courses each of R-COM3P and R-CYM (rituximab, cytarabine, methotrexate and intrathecal methotrexate with hydrocortisone). The primary endpoint is a 3-year event-free survival rate in paediatric patients (<18 years) with intermediate-risk disease. 100 patients (10 low-risk and 90 intermediate-risk) will enrol within a 4-year enrolment period and the follow-up period will be 3 years. 108 institutions are participating as of 1 January 2024 (64 university hospitals, 29 general hospitals, 12 children's hospitals and three cancer centres). ETHICS AND DISSEMINATION: This research was approved by the Certified Review Board at NHO Nagoya Medical Center (Nagoya, Japan) on 21 September 2021. Written informed consent is obtained from all patients and/or their guardians. The results of this study will be disseminated through peer-reviewed publications and conference presentations. STUDY REGISTRATION: Japan Registry of Clinical Trials, jRCTs041210104.

Clinical symptoms, biochemistry, and liver histology during the native liver period of progressive familial intrahepatic cholestasis type 2.

BACKGROUND: Progressive familial intrahepatic cholestasis type 2 (PFIC2) is an ultra-rare disease caused by mutations in the ABCB11 gene. This study aimed to understand the course of PFIC2 during the native liver period. METHODS: From November 2014 to October 2015, a survey to identify PFIC2 patients was conducted in 207 hospitals registered with the Japanese Society of Pediatric Gastroenterology, Hepatology, and Nutrition. Investigators retrospectively collected clinical data at each facility in November 2018 using pre-specified forms. RESULTS: Based on the biallelic pathogenic variants in ABCB11 and/or no hepatic immunohistochemical detection of BSEP, 14 Japanese PFIC2 patients were enrolled at seven facilities. The median follow-up was 63.2 [47.7-123.3] months. The median age of disease onset was 2.5 [1-4] months. Twelve patients underwent living donor liver transplantation (LDLT), with a median age at LDLT of 9 [4-57] months. Two other patients received sodium 4-phenylbutyrate (NaPB) therapy and survived over 60 months with the native liver. No patients received biliary diversion. The cases that resulted in LDLT had gradually deteriorated growth retardation, biochemical tests, and liver histology since the initial visit. In the other two patients, jaundice, growth retardation, and most of the biochemical tests improved after NaPB therapy was started, but pruritus and liver fibrosis did not. CONCLUSIONS: Japanese PFIC2 patients had gradually worsening clinical findings since the initial visit, resulting in LDLT during infancy. NaPB therapy improved jaundice and growth retardation but was insufficient to treat pruritus and liver fibrosis.

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.

Rituximab with standard LMB chemotherapy in pediatric high-risk mature B-cell non-Hodgkin lymphoma: A report from the JPLSG B-NHL14 trial.

BACKGROUND: The benefit of adding rituximab to standard lymphomes malins B (LMB) chemotherapy for children with high-risk mature B-cell non-Hodgkin lymphoma (B-NHL) has previously been demonstrated in an international randomized phase III trial, to which the Japanese Pediatric Leukemia/Lymphoma Study Group could not participate. METHODS: To evaluate the efficacy and safety of rituximab in combination with LMB chemotherapy in Japanese patients, we conducted a single-arm multicenter trial. RESULTS: In this study, 45 patients were enrolled between April 2016 and September 2018. A total of 33 (73.3%), 5 (11.1%), and 6 (13.3%) patients had Burkitt lymphoma/leukemia, diffuse large B-cell lymphoma, and aggressive mature B-NHL, not otherwise specified, respectively. Ten (22.2%) and 21 (46.7%) patients had central nervous system disease and leukemic disease, respectively. The median follow-up period was 47.5 months. Three-year event-free survival and overall survival were 97.7% (95% confidence interval, 84.9-99.7) and 100%, respectively. The only event was relapse, which occurred in a patient with diffuse large B-cell lymphoma. Seven patients (15.6%) developed Grade 4 or higher non-hematologic adverse events. Febrile neutropenia was the most frequent Grade 3 or higher adverse event after the pre-phase treatment, with a frequency of 54.5%. CONCLUSION: The efficacy and safety of rituximab in combination with LMB chemotherapy in children with high-risk mature B-NHL was observed in Japan.

Subtyping of Group 3/4 medulloblastoma as a potential prognostic biomarker among patients treated with reduced dose of craniospinal irradiation: a Japanese Pediatric Molecular Neuro-Oncology Group study.

BACKGROUND: One of the most significant challenges in patients with medulloblastoma is reducing the dose of craniospinal irradiation (CSI) to minimize neurological sequelae in survivors. Molecular characterization of patients receiving lower than standard dose of CSI therapy is important to facilitate further reduction of treatment burden. METHODS: We conducted DNA methylation analysis using an Illumina Methylation EPIC array to investigate molecular prognostic markers in 38 patients with medulloblastoma who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and treated with reduced-dose CSI. RESULTS: Among the patients, 23 were classified as having a standard-risk and 15 as high-risk according to the classic classification based on tumor resection rate and presence of metastasis, respectively. The median follow-up period was 71.5 months (12.0-231.0). The median CSI dose was 18 Gy (15.0-24.0) in both groups, and 5 patients in the high-risk group received a CSI dose of 18.0 Gy. Molecular subgrouping revealed that the standard-risk cohort included 5 WNT, 2 SHH, and 16 Group 3/4 cases; all 15 patients in the high-risk cohort had Group 3/4 medulloblastoma. Among the patients with Group 3/4 medulloblastoma, 9 of the 31 Group 3/4 cases were subclassified as subclass II, III, and V, which were known to an association with poor prognosis according to the novel subtyping among the subgroups. Patients with poor prognostic subtype showed worse prognosis than that of others (5-year progression survival rate 90.4% vs. 22.2%; p < 0.0001). The result was replicated in the multivariate analysis (hazard ratio12.77, 95% confidence interval for hazard ratio 2.38-99.21, p value 0.0026 for progression-free survival, hazard ratio 5.02, 95% confidence interval for hazard ratio 1.03-29.11, p value 0.044 for overall survival). CONCLUSION: Although these findings require validation in a larger cohort, the present findings suggest that novel subtyping of Group 3/4 medulloblastoma may be a promising prognostic biomarker even among patients treated with lower-dose CSI than standard treatment.

Stem cell challenges and opportunities.

Hepatocyte-like cells (HLCs) generated from human pluripotent stem cells (PSCs) exhibit hepatocytic properties in vitro; however, their engraftment and functionality in vivo remain unsatisfactory. Despite optimization of differentiation protocols, HLCs did not engraft in a mouse model of liver injury. In contrast, organ-derived hepatocytes reproducibly formed colonies in the liver injury mouse model. As an extension of the phenomenon observed in hematopoietic stem cells giving rise to colonies within the spleen, commonly referred to as "colony-forming units in spleen (CFU-s)", we hypothesize that "colony-forming units in liver (CFU-L)" serves as a reliable indicator of stemness, engraftment, and functionality of hepatocytes. The uniform expression of the randomly inactivated gene in a single colony, as reported by Sugahara et al. 2022, suggests that the colonies generated by isolated hepatocytes likely originate from a single cell. We, therefore, propose that CFU-L can be used to quantify the number of "hepatocytes that engraft and proliferate in vivo" as a quantitative assay for stem cells that utilize colony-forming ability, similar to that observed in hematopoietic stem cells.

Refractory Burkitt Lymphoma With False-positive and False-negative Mass Detected on Positron Emission Tomography-computed Tomography After Chemotherapy.

A 4-year-old boy with an abdominal mass extending from the spleen to the lower umbilicus was diagnosed with Burkitt lymphoma stage III. Because the fluorodeoxyglucose uptake on positron emission tomography (PET)-computed tomography of the residual splenic tumor remained elevated, splenectomy was performed. The PET-positive area was composed of inflammatory infiltrates, whereas the PET-negative area was composed of a viable tumor surrounded by necrotic or dying tumor cells. The residual tumor may have been false-negative for PET because of its poor proliferative potential. In this case, the comparison of PET-computed tomography and pathologic findings demonstrates the simultaneous presence of a false-positive inflammatory lesion and a false-negative residual tumor.

Pediatric Precision Medicine at the National Cancer Center Japan: Prospective Genomic Study of Pediatric Patients with Cancer as Part of the TOP-GEAR Project.

PURPOSE: This single-center, prospective molecular profiling study characterizes genomic alterations and identifies therapeutic targets in advanced pediatric solid tumors. METHODS: As part of the TOP-GEAR (Trial of Onco-Panel for Gene profiling to Estimate both Adverse events and Response by cancer treatment) project at the National Cancer Center (NCC), Japan, we enrolled pediatric patients with a refractory or recurrent disease during August 2016-December 2021 and performed genomic analysis of matched tumors and blood using originally developed cancer gene panels, NCC Oncopanel (ver. 4.0) and NCC Oncopanel Ped (ver. 1.0). RESULTS: Of 142 patients (age, 1-28 years) enrolled, 128 (90%) were evaluable for genomic analysis; 76 (59%) patients harbored at least one reportable somatic or germline alteration. The tumor samples were collected during the initial diagnosis in 65 (51%) patients, after treatment initiation in 11 (9%) patients, and upon either disease progression or relapse in 52 (41%) patients. The leading altered gene was TP53, followed by MYCN, MYC, CDKN2A, and CDK4. The commonly affected molecular processes were transcription, cell-cycle regulation, epigenetic modifiers, and RAS/mitogen-activated protein kinase signaling. Twelve (9%) patients carried pathogenic germline variants in cancer-predisposing genes. Potentially actionable findings were identified in 40 (31%) patients; to date, 13 (10%) patients have received the recommended therapy on the basis of their genomic profiles. Although four patients had access to targeted therapy through clinical trials, the agents were used in nine patients in an off-label setting. CONCLUSION: The implementation of genomic medicine has furthered our understanding of tumor biology and provided new therapeutic strategies. However, the paucity of proposed agents limits the full potential of actionability, emphasizing the significance of facilitating access to targeted cancer therapies.

Molecular characterization of long-term survivors of metastatic medulloblastoma treated with reduced-dose craniospinal irradiation.

BACKGROUND AND AIMS: Current standard treatment for metastatic medulloblastoma consists of 36 Gray (Gy) of craniospinal irradiation (CSI) supplemented with local irradiation and adjuvant chemotherapy after surgery. Although contemporary protocols have been designed to limit a radiation dose using risk-adapted CSI dosing to reduce neurocognitive morbidity, high-dose CSI remains the standard of care. Recently, the molecular classification of medulloblastoma has been emerging but its clinical significance has not been established particularly in patients with metastatic medulloblastoma treated with lower dose of CSI. METHODS: We molecularly analyzed three cases of metastatic medulloblastoma treated with 24.0 Gy of CSI by DNA methylation analysis using the Illumina EPIC array. RESULTS: All three patients had spinal metastases at the time of diagnosis. Postoperative treatment included multiple courses of chemotherapy, 24 Gy of CSI with focal boost to primary and metastatic sites, and high-dose chemotherapy. There was no disease progression observed during the 9.0, 7.7, and 5.7　years post-diagnosis follow-up. The molecular diagnosis was Group 3/4 in all three cases. Cases 1 and 2 belonged to Subtypes 7 and 4, both of which were reported to be good prognostic subtypes among the group. Case 3 belonged to Subtype 5 with MYC amplification. CONCLUSIONS: The present cases suggest that the novel subtype classification in Group 3/4 medulloblastoma may be useful for risk stratification of patients with metastatic medulloblastoma who received lower dose of CSI than standard treatment.

Cardiac mucosa in neonates.

BACKGROUND: The histology of the cardiac mucosa at the esophagogastric junction (EGJ) at birth is still a controversy. We conducted a histopathological study of the EGJ to clarify the morphology, and to determine the presence or absence of cardiac mucosa at birth. SUBJECTS: We examined 43 Japanese neonates and infants that are born prematurely or at full term. Death had occurred between 1 and 231 days after birth. RESULTS: Cardiac mucosa without parietal cells showing positivity for anti-proton pump antibody, adjacent to the most distal squamous epithelium, was observed in 32 (74%) of the 43cases. Such mucosa was evident in neonates that were full-term and had died within 14 days after birth. On the other hand, cardiac mucosa with parietal cells adjacent to squamous epithelium was noted in 10 cases (23%); the remaining one (2%) had columnar-lined esophagus. Squamous and columnar islands were observed in a single histological section from the EGJ in 22 (51%) of the 43 cases. Parietal cells were sparsely or densely present in the gastric antral mucosa. CONCLUSIONS: On the basis of these histological findings, we consider that cardiac mucosa exists in neonates and infants and can be defined as such, irrespective of the presence or absence of parietal cells (so-called oxyntocardiac mucosa). Neonates born prematurely or at full-term have cardiac mucosa in the EGJ just after birth, as is the case for Caucasian neonates.

A 15-Year-Old Boy with Primary Maxillary Bone Anaplastic Lymphoma Kinase-Positive Anaplastic Large Cell Lymphoma Relapsed with Rib Metastasis after Spontaneous Remission of a Maxillary Bone Lesion: A Case Report and Literature Review.

Anaplastic large cell lymphoma (ALCL) is a rare form of non-Hodgkin's lymphoma (NHL) in children, accounting for 10-15% of all NHL cases. ALCL is currently classified as follows: systemic anaplastic lymphoma kinase (ALK)-positive, systemic ALK-negative, primary cutaneous, and breast implant-associated ALCL. In children, systemic ALK-positive ALCL is the most common, and patients often present with extranodal involvement. We report a rare case of systemic ALK-positive ALCL with primary bone involvement in a 15-year-old male patient. Primary bone lymphoma is most commonly observed in diffuse large B-cell lymphoma and is extremely rare in systemic ALCL. Therefore, the clinical features and prognosis of primary bone ALCL remain unclear. Our patient had spontaneous remission of primary maxillary bone ALCL after gingival scraping but relapsed 12 months later with rib metastasis. Spontaneous remission of ALCL has been reported frequently in primary cutaneous ALCL and rarely in systemic ALCL. Our case demonstrates for the first time that systemic ALCL can also present as solitary bone involvement that can spontaneously remit. Because systemic ALCL is aggressive and has a risk of relapse, as in our case, it is important to consider ALCL in the differential diagnosis of primary bone lesions and to make a precise pathological diagnosis.

Intensification of treatment with vinca alkaloid does not improve outcomes in pediatric patients with Langerhans cell histiocytosis: results from the JPLSG LCH-12 study.

Chemotherapy with cytarabine, vincristine (VCR), and prednisolone has achieved low mortality rates in pediatric patients with Langerhans cell histiocytosis (LCH). However, relapse rates remain high, making event-free survival (EFS) rates unsatisfactory. A nationwide clinical trial, LCH-12, tested a modified protocol in which the early maintenance phase was intensified with increasing dosages of VCR. Patients newly diagnosed with multifocal bone (MFB) or multisystem (MS) LCH and aged < 20 years at diagnosis were enrolled between June 2012 and November 2017. Of the 150 eligible patients, 43 with MFB were treated for 30 weeks and 107 with MS LCH were treated for 54 weeks. One patient with MS LCH died of sepsis during the induction phase. The 3-year EFS rates among patients with MFB LCH, risk organ (RO)-negative MS LCH, and RO-positive MS LCH were 66.7% (95% confidential interval [CI], 56.5-77.0%), 66.1% (95% CI 52.9-76.4%), and 51.1% (95% CI 35.8-64.5%), respectively, similar to previously observed rates. EFS rates were significantly lower in patients with disease activity scores > 6 than in those with scores ≤ 6. The strategy that included more intense treatment with VCR was not effective. Other strategies are required to improve outcomes in patients with pediatric LCH.