Diffuse Leptomeningeal Glioneuronal Tumor in an Adult: A Diagnostic Challenge

Here we report a rare case of diffuse leptomeningeal glioneuronal tumor (DLGNT) in a 35-year-old man, who was misdiagnosed twice as having tuberculosis meningitis and later racemose neurocysticercosis. His delayed diagnosis of DLGNT might be due to prevalence of tuberculosis in our country, similarity in magnetic resonance imaging finding of prominent leptomeningeal enhancement in different cisterns of brain, and extreme rarity of DLGNT in the adults. So, it should be differentiated clinically and radiographically from granulomatous or infectious conditions. Hence, a timely histologic diagnosis through a leptomeningeal biopsy of the brain and spinal cord in case of unusual leptomeningeal enhancement with uncertain laboratory findings is essential because cytological examination of the cerebrospinal fluid in DLGNT is known to be negative.

Case Report: Unusual High-Grade Diffuse Leptomeningeal Glioneuronal Tumor Mimicking Tuberculous Meningitis in a Child From an Endemic Region

Background: Diffuse leptomeningeal glioneuronal tumor (DL-GNT) is a new entity described in the 2016 World Health Organization (WHO) classification of brain tumors. While DL-GNT is predominantly an indolent tumor that affects young boys, high-grade DL-GNT is unusual and seldom reported in children.Case Presentation: In this report, we describe the challenges and pitfalls associated with diagnosing this high-grade variant in a tuberculosis-endemic region. We highlight the importance of identifying non-typical imaging findings, i.e., non-enhancing cystic lesions with high T2 signal along the leptomeningeal surface, that may expedite the diagnosis of this condition. Histopathologic correlations with MR spectroscopy findings are also discussed.Conclusion: We provide the first clinical imaging report of utilizing MR spectroscopy to distinguish DL-GNT from tuberculosis with histopathologic correlation.

EPID-16. DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR IN PEDIATRIC PATIENTS: A QUANTITATIVE EXPLORATION

BACKGROUND Diffuse 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. METHODS We report four institutional cases of pediatric DLGNT diagnosed between 2000-2020 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. RESULTS 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. When including limited data, longer duration of symptoms by presentation (HR=1.03, P=0.03) was statistically predictive of shorter overall survival. CONCLUSIONS This is the first quantitative study of pediatric DLGNT clinical course. More 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.

Spinal Cord Diffuse Leptomeningeal Glioneuronal Tumor Presenting without Leptomeningeal Dissemination

<b><i>Background and Importance:</i></b> Diffuse leptomeningeal glioneuronal tumor (DLGNT) represents a provisional entity in the 2016 World Health Organization classification of tumors; it is characterized by a widespread leptomeningeal growth and oligodendroglial-like cytology. To this day, 4 pediatric patients have been reported to present with an isolated spinal cord tumor in the absence of leptomeningeal dissemination. Gross total resection (GTR) was achieved in only 1 patient. We present the clinical and technical nuances of this unique type of tumor, as well as the second reported case of GTR in a patient with DLGNT. <b><i>Clinical Presentation:</i></b> A 4-year-old boy presented to the emergency department after an episode of flaccid paralysis of bilateral lower extremities. MRI showed an intramedullary spinal cord tumor centered at T8. The patient was taken to the operative room, where a laminectomy and tumor resection were performed; cystic and solid tumor components were identified. Pathology report was consistent with DLGNT. After achieving GTR, patient is free of recurrence after a 15-month follow-up. <b><i>Conclusion:</i></b> No standard treatment for DLGNT has been identified. Current literature report surgery and chemotherapy with variable success rates. DLGNT presenting as an isolated intramedullary tumor is an uncommon condition which progression appears to be halted when treated promptly. Identifying solid and cystic components of this tumor is crucial for achieving GTR.

Diffuse leptomeningeal glioneuronal tumor with high-grade features masquerading as tubercular meningitis—a case report

Background Diffuse leptomeningeal glioneuronal tumor (DLGNT) has been recently described in the literature. The complete neuroimaging spectrum and histopathological characteristics of this entity are yet to be elucidated. In an endemic region, diffuse leptomeningeal enhancement on neuroimaging with associated communicating hydrocephalus is usually suggestive of infective meningitis and the patients are started on empirical anti-microbial therapy. However, it is important to consider other differential diagnosis of leptomeningeal enhancement in such cases, particularly if the clinical condition does not improve on anti-microbial therapy. An early diagnosis of a neoplastic etiology may be of particular importance as the treatment regimens vary considerably depending on the underlying disease condition. Case presentation In this case report, we describe a case of DLGNT with high-grade histopathological features which was initially managed as tubercular meningitis based on the initial neuroimaging findings. Due to worsening of the clinical course and subsequent imaging findings at follow-up, a diagnosis of DLGNT was considered and subsequently proven to be DLGNT with features of anaplasia on histopathological examination of leptomeningeal biopsy specimen. Conclusion This case highlights the importance of recognizing certain subtle finding on MRI which may help in an early diagnosis of DLGNT which is crucial for appropriate treatment.

RARE-23. DIFFUSE LEPTOMENINGEAL GLIONEURONAL TUMOR: A CASE SERIES

Introduction Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare diagnosis first incorporated into the WHO Classification of Tumors of the Central Nervous System in 2016. Though historically considered indolent, emerging evidence suggests that the biological behavior of these tumors may be further classified by molecular features of prognostic significance. Methods A retrospective review was conducted in accordance with IRB approval of patients with the histologic diagnosis of DLGNT. Demographic, clinical, and molecular data where abstracted from the medical record when available. Results 10 patients were identified (M = 8, F = 2). Median age at diagnosis was 6 years (range 0.3–21 years), and the most common symptoms at diagnosis were related to obstructive hydrocephalus, for which 3 patients required CSF diversion. MRI findings included diffuse leptomeningeal thickening, nodularity, or coating of the subarachnoid or ependymal surfaces. Histologically, these tumors expressed variable features of neuronal and/or glial differentiation. Four patients (40%) were treated with radiation therapy (all craniospinal), which was upfront for 2 patients. Chemotherapy regimens used included temozolomide, carboplatin and vincristine and vinblastine. NTRK or BRAF-targeted therapy were used upon progression. At follow-up, 6/10 had stable disease (4/6 of whom were on second line therapy), 1 had partial response, 1 passed away from sepsis and 2 were lost to follow-up. The median progression-free survival for the four patients who developed disease progression was 26 months (range 12–34 months). Next generation sequencing of the tumor tissue performed using a high-multiplex PCR-based NGS panel detected BRAF-KIAA1549 (4 patients) and NTRK (1 patient) fusions. Conclusions DLGNT are rare tumors with scarce data about imaging characteristic and standard of care treatment. Our case series reinforces current literature that although these tumors appear low-grade, they can be clinically aggressive. Further study is needed regarding molecular diagnosis and profiling treatment strategies.