Diffuse Leptomeningeal Glioneuronal Tumor Research Articles

Local intracerebral form of diffuse leptomeningeal glioneuronal tumor – a new entity of the group of epileptogenic neoplasms?

Local intracerebral form of diffuse leptomeningeal glioneuronal tumor – a new entity of the group of epileptogenic neoplasms?

Unraveling morphology, methylation profiling, and diagnostic challenges in BRAF-Mutant pediatric glial and glioneuronal tumors.

To elucidate the relationship between DNA methylation profiling (DMP) and pathological diagnosis (PD) in pediatric glial and glioneuronal tumors with B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations, addressing their diagnostic challenges. This retrospective study, conducted in Saudi Arabia, analyzed 47 cases from the Children's Brain Tumor Network online database using scanned images, next-generation sequencing data, and methylation profiles processed using the Heidelberg methylation brain tumor classifiers v12.5 and v12.8. The data was last access on 10 November 2023. The highest prevalence of BRAF mutations was observed in pilocytic astrocytoma and ganglioglioma. The DMP was consistent with PD in 23 cases, but discrepancies emerged in others, including diagnostic changes in diffuse leptomeningeal glioneuronal tumor and polymorphous low-grade neuroepithelial tumor of the young. A key inconsistency appeared between a pilocytic astrocytoma MC and a glioneuronal tumor PD. Two high-grade astrocytomas were misclassified as pleomorphic xanthoastrocytomas. Additionally, low variant allelic frequency in gangliogliomas likely contributed to misclassifications as control in 5 cases. This study emphasized the importance of integrating DMP with PD in diagnosing pediatric glial and glioneuronal tumors with BRAF mutations. Although DMP offers significant diagnostic insights, its limitations, particularly in cases with low tumor content, necessitate cautious interpretation, as well as its use as a complementary diagnostic tool, rather than a definitive method.

Unraveling morphology, methylation profiling, and diagnostic challenges in BRAF-Mutant pediatric glial and glioneuronal tumors.

To elucidate the relationship between DNA methylation profiling (DMP) and pathological diagnosis (PD) in pediatric glial and glioneuronal tumors with B-Raf proto-oncogene, serine/threonine kinase (BRAF) mutations, addressing their diagnostic challenges. This retrospective study, conducted in Saudi Arabia, analyzed 47 cases from the Children's Brain Tumor Network online database using scanned images, next-generation sequencing data, and methylation profiles processed using the Heidelberg methylation brain tumor classifiers v12.5 and v12.8. The data was last access on 10 November 2023. The highest prevalence of BRAF mutations was observed in pilocytic astrocytoma and ganglioglioma. The DMP was consistent with PD in 23 cases, but discrepancies emerged in others, including diagnostic changes in diffuse leptomeningeal glioneuronal tumor and polymorphous low-grade neuroepithelial tumor of the young. A key inconsistency appeared between a pilocytic astrocytoma MC and a glioneuronal tumor PD. Two high-grade astrocytomas were misclassified as pleomorphic xanthoastrocytomas. Additionally, low variant allelic frequency in gangliogliomas likely contributed to misclassifications as control in 5 cases. This study emphasized the importance of integrating DMP with PD in diagnosing pediatric glial and glioneuronal tumors with BRAF mutations. Although DMP offers significant diagnostic insights, its limitations, particularly in cases with low tumor content, necessitate cautious interpretation, as well as its use as a complementary diagnostic tool, rather than a definitive method.

LGG-12. INTEGRATED CLINICAL AND MOLECULAR CHARACTERIZATION OF 200 DISSEMINATED PEDIATRIC LOW-GRADE GLIOMAS

Abstract Pediatric low-grade gliomas (PLGG) have excellent outcomes overall but are a major clinical challenge when disseminated. Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a recognised entity both clinically and pathologically, however many disseminated LGG (DLGG) fall outside this diagnosis. To better understand the clinical and molecular features of DLGG as well as risk factors for dissemination, we assembled an international consortium of 30 sites, contributing over 200 patients with clinical annotation, along with genomic and methylation profiling. DLGG have worse progression-free (PFS) and overall survival (OS) than PLGG overall (p<0.0001). Seventy (35%) presented with a localized mass and secondary dissemination, including some with initial gross-total resection. The most common growth pattern observed (n=77, 40%) is a dominant suprasellar/optic pathway tumor with leptomeningeal drop-metastases involving the brainstem and spinal cord. Only 27 (14%) patients had diffuse tumors (without an identifiable dominant mass), and these had significantly worse OS (p=0.03). The most common pathologic diagnosis was pilocytic/pilomyxoid astrocytoma (n=92; 53%). DLGNT comprised a minority of cases (n=23, 14%), with a trend (p=0.056) towards worse survival compared to other diagnoses. The most frequent molecular alteration was BRAF fusion (78/151 with molecular testing; 52%), followed by FGFR mutations or fusions (18/151; 12%). BRAF V600E was underrepresented (14/151; 9%). 1p deletion was rare (17 patients) but highly associated with DLGNT. Methylation classification (n=70) was highly concordant with histologic diagnoses rather than clinical behavior. Importantly, patients who received upfront targeted therapies (TT; BRAF and/or MEK inhibition, n=9) had better PFS compared to those receiving chemotherapy (n=146, p=0.05). Furthermore, patients who were treated sequentially with chemo then TT had longer PFS on TT (p=0.011). This study presents the largest cohort of DLGG to date, expanding our understanding of the clinical, pathologic, and molecular features of this disease and supports the use of upfront targeted therapy.

Pediatric Diffuse Leptomeningeal Glioneuronal Tumors: Diagnosis, Follow-up, and Treatment Options.

To highlight the diagnosis, follow-up, and treatment options for diffuse leptomeningeal glioneuronal tumor (DLGNT) by examining pediatric patients diagnosed with DLGNT by molecular pathological evaluation and next generation sequencing at our center. In this retrospective analysis, patients diagnosed with DLGNT between January 2017 and December 2022 are outlined according to their demographic data, radiological data, pathology results, treatments, and follow-up data. Four patients were diagnosed with DLGNT. All the patients were male. The mean age was 6.5 years. All but one patient had symptoms of increased intracranial pressure. An open biopsy was obtained from all patients for diagnosis. Three patients received radiotherapy and chemotherapy after the diagnosis. Two patients died during their follow-up, one of them in the early postoperative period. Two patients were clinically and radiologically stable in their follow-up after treatment. Further work with larger cohorts is required to determine a common algorithm for DLGNT treatment and follow-up. This analysis may keep this entity in mind in patients with pediatric communicating hydrocephalus and may present insight into diagnosis, follow-up, and treatment options.

Dural and Leptomeningeal Diseases: Anatomy, Causes, and Neuroimaging Findings.

Meningeal lesions can be caused by various conditions and pose diagnostic challenges. The authors review the anatomy of the meninges in the brain and spinal cord to provide a better understanding of the localization and extension of these diseases and summarize the clinical and imaging features of various conditions that cause dural and/or leptomeningeal enhancing lesions. These conditions include infectious meningitis (bacterial, tuberculous, viral, and fungal), autoimmune diseases (vasculitis, connective tissue diseases, autoimmune meningoencephalitis, Vogt-Koyanagi-Harada disease, neuro-Behçet syndrome, Susac syndrome, and sarcoidosis), primary and secondary tumors (meningioma, diffuse leptomeningeal glioneuronal tumor, melanocytic tumors, and lymphoma), tumorlike diseases (histiocytosis and immunoglobulin G4-related diseases), medication-induced diseases (immune-related adverse effects and posterior reversible encephalopathy syndrome), and other conditions (spontaneous intracranial hypotension, amyloidosis, and moyamoya disease). Although meningeal lesions may manifest with nonspecific imaging findings, correct diagnosis is important because the treatment strategy varies among these diseases. ©RSNA, 2023 Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Quiz questions for this article are available through the Online Learning Center.

LGG-12. CLINICAL AND MOLECULAR FEATURES OF DISSEMINATED PEDIATRIC LOW-GRADE GLIOMA

Abstract Although most pediatric LGG (PLGG) have excellent long-term survival, there is a subset of cases that disseminate throughout the neuraxis (DLGG) that have very poor outcomes. The reason for this aggressive behavior is unknown but we hypothesize that distinct and specific biological mechanisms underlie the metastatic ability. The methylation-based class of diffuse leptomeningeal glioneuronal tumor (DLGNT) is characterized by MAPK pathway activating fusions with chromosome 1p loss, 19q loss, and/or 1q gain. However, it is unknown what proportion of DLGG match the DLGNT group, and which other methylations classes are at risk of metastasis. To improve our understanding of this rare patient population, we created an international DLGG consortium. Data from the first 68 cases shows a broad age distribution and no sex predilection. As expected, DLGG has much worse prognosis than the overall PLGG population. Virtually all DLGG progress at 5 years, compared to a quarter of other PLGG, and DLGG are 5-times more likely to die at 10 years. We observe three patterns of dissemination – 35% present with a localized mass and have secondary dissemination, 50% with disseminated tumor and a clear dominant mass, and 15% with disseminated disease without a dominant mass. In 47 patients with molecular testing, BRAF fusions accounted for 64% of driver alterations. Additional alterations were identified less frequently, including BRAF V600E (9%), FGFR1 alterations (9%), and KRAS mutations (4%). In 25 patients with methylation profiling, 10 (40%) successfully classified with a calibrated score above 0.8, illustrating that many cases do not fit a defined methylation group. The most common methylation classification was pilocytic astrocytoma (5 patients), and surprisingly only two patients classified as DLGNT. In sum this study illustrates the variable clinical behaviour associated with metastasis in PLGG and expands the range of molecular driver alterations, including ones previously unreported in DLGNT.

Diffuse Leptomeningeal Glioneuronal Tumor (DLGNT) with Direct Cystic Infiltration of the Optic Chiasm and Tracts (P1-9.003)

<h3>Objective:</h3> N/A <h3>Background:</h3> Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare pediatric neoplasm categorized by the WHO in 2016. It is characterized by communicating hydrocephalus, slow tumor growth, CSF with absence of tumor cells, and MRI showing diffuse leptomeningeal enhancement and cystic changes. Here we present, to our knowledge, the first case in which direct cystic tumor infiltration of the optic apparatus was the initial manifestation. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> A 3-year-old boy developed emesis, altered mental status, bilateral leg weakness, and decreased visual acuity to 20/125 OD and 20/160 OS. MRI showed hydrocephalus and diffuse leptomeningeal enhancement of the brain and spine. Lumbar puncture showed pleocytosis, elevated protein, positive enterovirus PCR, and opening pressure of 55 cm H2O. VP shunt was placed for presumed enterovirus meningitis. Symptoms of hydrocephalus resolved but vision did not improve. Exam showed optic disc pallor bilaterally and no papilledema. OCT demonstrated retinal nerve fiber layer thinning bilaterally. Visual decline progressed despite normalization of ICP. Repeat MRI brain/orbits showed multiple new subpial cysts along the optic tracts and optic chiasm. Filum biopsy showed rare inflammatory cell. Review of the pathology and radiological findings led to a consensus of DLGNT with cysts compressing and infiltrating optic chiasm and nerves. The patient was started on the MEK inhibitor trametinib, with stabilization of MRI findings and vision, but unfortunately without visual improvement. <h3>Conclusions:</h3> Pathologic confirmation of DLGNT can be difficult as safely obtained biopsy samples are typically small. In this case, bilateral optic neuropathy developed due to infiltration of the optic nerves, chiasm and tracts, while papilledema was never seen. MEK inhibitor therapy was initiated with Trametinib leading to stabilization in disease burden. This diagnosis should be considered in pediatric patients with communicating hydrocephalus, diffuse leptomeningeal enhancement, and elevated CSF protein with otherwise normal profile including absence of tumor cells. <b>Disclosure:</b> Dr. Paddock has nothing to disclose. Dr. Dinkin has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for WILSON ELSER MOSKOWITZ EDELMAN &amp; DICKER LLP. Dr. Dinkin has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Rehabilitation Alternative Services, Inc.. Dr. Dinkin has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for AMFS / Medical Experts Nationwide. Dr. Dinkin has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Bekman, Marder, Hopper, Malarkey &amp; Perlin, L.L.C.. Dr. Dinkin has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Northwestern Mutual. Dr. Dinkin has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Young Conaway Stargatt &amp; Taylor.

Integrated genetic profiling of archival pediatric high-grade glial tumors and reassessment with 2021 WHO classification of paediatric CNS tumours

Though rare, pediatric high-grade gliomas (pHGG) are a leading cause of cancer-related mortality in children. We wanted to determine whether our currently available clinical laboratory methods could better define diagnosis for pHGG that had been archived at our institution for the past 20 years (1998 to 2017). We investigated 33 formalin-fixed paraffin-embedded pHGG using ThermoFisher Oncoscan SNP microarray with somatic mutation analysis, Sanger sequencing, and whole genome sequencing. These data were correlated with historical histopathological, chromosomal, clinical, and radiological data. Tumors were subsequently classified according to the 2021 WHO Classification of Paediatric CNS Tumours. All 33 tumors were found to have genetic aberrations that placed them within a 2021 WHO subtype and/or provided prognostic information; 6 tumors were upgraded from WHO CNS grade 3 to grade 4. New pHGG genetic features were found including two small cell glioblastomas with H3 G34 mutations not previously described; one tumor with STRN-NTRK2 fusion; and a congenital diffuse leptomeningeal glioneuronal tumor without a chromosomal 1p deletion but with KIAA1549-BRAF fusion. Overall, the combination of laboratory methods yielded key information for tumor classification. Thus, even small studies of these uncommon tumor types may yield new genetic features and possible new subtypes that warrant future investigations.

Rapidly progressive diffuse leptomeningeal glioneuronal tumor in an adult female: illustrative case.

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare brain tumor only recently classified by the World Health Organization in 2016 and has few reports on its incidence in adults. The authors describe a case of DLGNT presenting in a 47-year-old female with seizures, cranial neuropathies, and communicating hydrocephalus with rapid clinical progression. Workup demonstrated progressive leptomeningeal enhancement of the skull base, cranial nerves, and spine, and communicating hydrocephalus. Elevated serum rheumatological markers and early response to systemic corticosteroids and immunosuppressant therapy complicated the diagnosis. Multiple biopsy attempts were required to obtain diagnostic tissue. Pathology demonstrated hypercellularity surrounding leptomeningeal vessels with nuclear atypia, staining positive for GFAP, Olig2, S100, and synaptophysin. Molecular pathology demonstrated loss of chromosome 1p, BRAF overexpression but no rearrangement, and H3K27 mutation. Repeat cerebrospinal fluid (CSF) diversion procedures were required for hydrocephalus management due to high CSF protein content. This report describes a rare, aggressive, adult presentation of DLGNT. Leptomeningeal enhancement and communicating hydrocephalus should raise suspicion for this disease process. Biopsy at early stages of disease progression is essential for early diagnosis and prompt treatment. Further study into the variable clinical presentation, histological and molecular pathology, and optimal means of diagnosis and management is needed.

Diffuse Leptomeningeal Glioneuronal Tumor Involving Circle of Willis and Spinal Nerve Roots.

Diffuse Leptomeningeal Glioneuronal Tumor Involving Circle of Willis and Spinal Nerve Roots.

DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR: A RARE CAUSE OF MALIGNANT PLEURAL EFFUSION

DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR: A RARE CAUSE OF MALIGNANT PLEURAL EFFUSION

Diffuse leptomeningeal glioneuronal tumor (DLGNT) with hydrocephalus as an initial symptom mimicking tuberculous meningitis: A case report.

The Article Abstract is not available.

Prognostic factors in diffuse leptomeningeal glioneuronal tumor (DLGNT): a systematic review

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare tumor, first described by the WHO Classification of Central Nervous System Tumors in 2016. The clinical course is variable. Most tumors have low-grade histological findings although some may have more aggressive features. The goal of this systematic review was to identify prognostic factors for poor overall survival (OS). We performed a systematic review using three databases (PubMed, Google Scholar, and Embase) and the following search terms: diffuse leptomeningeal glioneuronal tumor, DLGNT, DLMGNT. Statistical analysis was performed using Statistica 13.3. We included 34 reports in our review comprising 63 patients, published from 2016 to 2022. The median OS was 19months (range: 12-51months). Using multivariable Cox survival analysis, we showed that Ki-67 ≥ 7%, age > 9years, symptoms of elevated intracranial pressure (ICP) at admission, and the presence of contrast-enhancing intraparenchymal tumor are associated with poor OS. Receiver operating characteristic (ROC) analysis identified Ki-67 ≥ 7% as a significant predictor of poor OS. Signs or symptoms of increased ICP with imaging findings of diffuse leptomeningeal enhancement should raise suspicion for DLGNT. In our systematic review, Ki-67 ≥ 7% was the most important prognostic factor for OS in DLGNT. The presence of intraparenchymal tumor with contrast enhancement was thought to represent disease progression and, together with patient age, was associated with poor OS.

Teaching NeuroImage: A Rare Pediatric Case of Diffuse Leptomeningeal Glioneuronal Tumor.

A 6-year-old boy, with an unremarkable birth history and developmental history notable only for intellectual disability, developed expressive aphasia and intermittent vomiting in 3 weeks. Brain MRI showed communicating hydrocephalus and characteristic diffuse subpial cystic lesions throughout the surface (Figure). His symptom of vomiting was relieved after he was given a ventricular-peritoneal shunt (valve pressure set as 140 mm H2O) and meningeal-cortical biopsy. The final diagnosis was diffuse leptomeningeal glioneuronal tumor, a new entity in the 2016 WHO classification of CNS tumors.1 He was referred to a local oncology center because chemotherapy had been proposed as first-line treatment.2

PATH-16. Noninvasive diagnosis of gliomas through CSF cfDNA sequencing in pediatric and adolescent and young adult (AYA) patients

Abstract PURPOSE: A subset of pediatric, adolescent and young adult (AYA) gliomas are located in the brainstem, eloquent locations, or present with diffuse/leptomeningeal disease, and are associated with high risk and low yield of biopsy. At the same time, accurate molecular diagnosis is necessary to direct optimal therapy. In such cases, analysis of cell free DNA (cfDNA) form cerebral spinal fluid (CSF) may represent a diagnostic alternative to biopsy. METHODS: We investigated the utility of CSF cfDNA sequencing through a stepwise approach, using clinically validated, targeted molecular assays. Testing was performed using a broad hybrid capture next generation sequencing assay (MSK-IMPACT) and subsequent targeted digital droplet PCR in a subset of cases. RESULTS: We analyzed 17 CSF samples from 17 pediatric (n=6) and AYA (n=11) glioma patients with primary or recurrent disease. Thirteen had tumors located within the brainstem, and four had leptomeningeal involvement. Somatic alterations were detected in 12/17 samples (71%). In 3/4 patients with leptomeningeal involvement, cfDNA testing revealed a BRAF fusion consistent with the diagnosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Among the 13 patients with brainstem involvement, four had somatic H3 K27M mutations, three had IDH mutations, and one had TP53 and ATRX mutations; five patients had no detectable mutations. CONCLUSION: In our analysis, we found that established glioma hotspot mutations were able to be detected within the CSF. We propose that in patients for whom tissue biopsy is high risk, not feasible, or tissue was nondiagnostic, CSF cfDNA sequencing has a substantial diagnostic yield and should be considered as a valuable novel diagnostic tool. Ongoing research is aiming to further increase the sensitivity of cfDNA testing, especially in patients with very low levels of CSF cfDNA.

Contemporary outcomes of diffuse leptomeningeal glioneuronal tumor in pediatric patients: A case series and literature review

BackgroundDiffuse leptomeningeal glioneuronal tumor (DLGNT), also known as oligodendrogliomatosis, is a rare neuro-oncologic condition along the neuraxis that remains poorly understood in children. We sought to describe our institutional experience and quantitively summarize the clinical survival and prognostic features of DLGNT in the pediatric population across the contemporary literature. MethodsWe report four institutional cases of pediatric DLGNT diagnosed between 2000 and 2020 based on retrospective review of our records, and performed a comprehensive literature search for published cases from 2000 onwards to create an integrated cohort for analysis. Kaplan-Meier estimations, Fisher’s exact test, and logistic regression were utilized to interrogate the data. ResultsOf our four cases, three females aged 2-, 3- and 13-years old at diagnosis survived 6-years, 3-years and 14-months respectively, and one male aged 5-years old at diagnosis was still alive 5 years later. Our overall integrated cohort consisted of 54 pediatric DLGNT patients, with 19 (35%) female and 35 (65%) male patients diagnosed at an average age of 6.4 years (range, 1.3–17 years) by means of surgical biopsy. Chemotherapy was used in 45 cases (83%), and mean follow-up time of 54 months (range, 3–204). Across the entire cohort, overall survival 1 month after diagnosis was 96% (95% CI 86–99%), and by 10 years was 69% (95% CI 49–82%). On multivariate analysis of complete data, chemotherapy treatment (HR=0.23, P = 0.04) was statistically predictive of longer overall survival. ConclusionsMore than 2-out-of-3 pediatric DLGNT patients survive beyond one decade. Chemotherapy is statistically associated with longer survival in DLGNT pediatric patients and should form the core of any treatment regimen in this setting. Early detection by means of judicious imaging and surgical biopsy for tissue diagnosis can lead to earlier treatment and likely superior outcomes.

Analysis of genetic aberrations in pediatric low-grade gliomas: the experience of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology

Low grade gliomas (LGGs) are the most common brain tumors in children. Our retrospective-prospective study of biological characteristics of sporadic LGGs (not associated with neurofibromatosis type I) included 233 patients aged 0 to 18 years who had been diagnosed and/or treated at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology, and Immunology in the period from 2009 to 2021. The study was approved by the Independent Ethics Committee and the Scientific Council of the D. Rogachev NMRCPHOI. The median age at the diagnosis was 5 years 4 months (2 months – 17 years). Among the LGGs, the following histological variants were identified: pilocytic astrocytoma (n = 191; 82%), pleomorphic xanthoastrocytoma (n = 16; 7%), ganglioglioma (n = 7; 3%), desmoplastic infantile ganglioglioma (n = 4; 2%), diffuse leptomeningeal glioneuronal tumor (n = 5; 2%), dysembryoplastic neuroepithelial tumor (n = 2, 1%), and diffuse astrocytoma (n = 1; 0,5%). The tumors were located in: the suprasellar region (n = 98; 42%), the brainstem (n = 40; 17%), the cerebellum (n = 35; 15%), the hemispheres (n = 34; 15%) etc. The KIAA1549-BRAF fusion was the most common molecular genetic alteration (n = 107; 46%). The second most frequent genetic aberration was the BRAF V600E mutation (n = 44; 19%). Rare molecular genetic events leading to the activation of the MAPK signaling pathway were detected in 13 (6%) patients. The H3 K27M mutation associated with an aggressive clinical course was identified in three patients with brainstem LGGs (1%). These findings point to the importance of molecular profiling of pediatric LGGs for the selection of an effective strategy for molecular diagnosis and optimal clinical care.

Next-generation sequencing of cerebrospinal fluid for clinical molecular diagnostics in pediatric, adolescent and young adult brain tumor patients.

Safe sampling of central nervous system tumor tissue for diagnostic purposes may be difficult if not impossible, especially in pediatric patients, and an unmet need exists to develop less invasive diagnostic tests. We report our clinical experience with minimally invasive molecular diagnostics using a clinically validated assay for sequencing of cerebrospinal fluid (CSF) cell-free DNA (cfDNA). All CSF samples were collected as part of clinical care, and results reported to both clinicians and patients/families. We analyzed 64 CSF samples from 45 pediatric, adolescent and young adult (AYA) patients (pediatric = 25; AYA = 20) with primary and recurrent brain tumors across 12 histopathological subtypes including high-grade glioma (n = 10), medulloblastoma (n = 10), pineoblastoma (n = 5), low-grade glioma (n = 4), diffuse leptomeningeal glioneuronal tumor (DLGNT) (n = 4), retinoblastoma (n = 4), ependymoma (n = 3), and other (n = 5). Somatic alterations were detected in 30/64 samples (46.9%) and in at least one sample per unique patient in 21/45 patients (46.6%). CSF cfDNA positivity was strongly associated with the presence of disseminated disease at the time of collection (81.5% of samples from patients with disseminated disease were positive). No association was seen between CSF cfDNA positivity and the timing of CSF collection during the patient's disease course. We identified three general categories where CSF cfDNA testing provided additional relevant diagnostic, prognostic, and/or therapeutic information, impacting clinical assessment and decision making: (1) diagnosis and/or identification of actionable alterations; (2) monitor response to therapy; and (3) tracking tumor evolution. Our findings support broader implementation of clinical CSF cfDNA testing in this population to improve care.

Emerging glioneuronal and neuronal tumors: case-based review

Glioneuronal and neuronal tumors (GNTs) are rare heterogeneous central nervous system tumors characterized by slow growth and favorable outcomes, but are often associated with diagnostic difficulties. A thorough analysis of three rare and recently recognized GNTs was performed in the context of clinicopathological features and molecular genetic characterization. The current spinal diffuse leptomeningeal glioneuronal tumor (DLGNT) was characterized with oligodendroglioma-like tumor with chromosome 1p/19q codeletion without IDH mutations and KIAA1549:BRAF fusion. The current occipital multinodular and vacuolating neuronal tumor (MVNT) was characteristic of the variable-sized vague nodules consisted of gangliocytic tumor cells with intracytoplasmic and pericellular vacuolation and the next-generation sequencing (NGS) revealed MAP2K1 p.Q56_V60del. A diffuse glioneuronal tumor with oligodendroglioma-like features and nuclear clusters (DGONC) of the amygdala was characterized by oligodendroglia-like cells and nuclear clusters, and monosomy 14. From the current cases and literature review, we found that DLGNT commonly occurs in the spinal cord and can make mass and more commonly have KIAA1549:BRAF fusion; MVNT is a neoplasm rather than malformation and MAP2K1 deletion is one of the hallmarks of this tumor; although DGONC may require a methylation profile, we can reach a diagnosis through its unique histology, monosomy 14, and exclusion diagnosis without a methylation profile.