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

Understanding diffuse leptomeningeal glioneuronal tumors

INTODUCTION

Diffuse leptomeningeal glioneuronal tumors (DLGNTs) pose a rare and challenging entity within pediatric central nervous system neoplasms. Despite their rarity, DLGNTs exhibit complex clinical presentations and unique molecular characteristics, necessitating a deeper understanding of their diagnostic and therapeutic nuances.

METHODS

This review synthesizes contemporary literature on DLGNT, encompassing epidemiology, clinical manifestations, pathological features, treatment strategies, prognostic markers, and future research directions. To compile the existing body of knowledge on DLGNT, a comprehensive search of relevant databases was conducted.

RESULTS

DLGNT primarily affects pediatric populations but can manifest across all age groups. Its diagnosis is confounded by nonspecific clinical presentations and overlapping radiological features with other CNS neoplasms. Magnetic resonance imaging (MRI) serves as a cornerstone for DLGNT diagnosis, revealing characteristic leptomeningeal enhancement and intraparenchymal involvement. Histologically, DLGNT presents with low to moderate cellularity and exhibits molecular alterations in the MAPK/ERK signalling pathway. Optimal management of DLGNT necessitates a multidisciplinary approach encompassing surgical resection, chemotherapy, radiotherapy, and emerging targeted therapies directed against specific genetic alterations. Prognostication remains challenging, with factors such as age at diagnosis, histological subtypes, and genetic alterations influencing disease progression and treatment response. Long-term survival data are limited, underscoring the need for collaborative research efforts.

CONCLUSION

Advancements in molecular profiling, targeted therapies, and international collaborations hold promise for improving DLGNT outcomes. Harnessing the collective expertise of clinicians, researchers, and patient advocates, can advance the field of DLGNT research and optimize patient care paradigms.

Imaging of pediatric glioneuronal and neuronal tumors

Glioneuronal tumors (GNTs) are an expanding group of primary CNS neoplasms, commonly affecting children, adolescents and young adults. Most GNTs are relatively indolent, low-grade, WHO grade I lesions. In the pediatric age group, GNTs have their epicenter in the cerebral cortex and present with seizures. Alterations in the mitogen-activated protein kinase (MAPK) pathway, which regulates cell growth, are implicated in tumorigenesis. Imaging not only plays a key role in the characterization and pre-surgical evaluation of GNTs but is also crucial role in follow-up, especially with the increasing use of targeted inhibitors and immunotherapies. In this chapter, we review the clinical and imaging perspectives of common pediatric GNTs.

Spinal Cord Neoplasms

OBJECTIVE

This article discusses the diagnostic approach to patients with suspected neoplasms of the spinal cord and reviews the most common primary and metastatic spinal neoplasms and their presentations.

LATEST DEVELOPMENTS

Neoplasms of the spinal cord are rare entities that can involve the spinal cord parenchyma, the dura and leptomeninges, or the extradural space. The most common intramedullary spinal cord neoplasms are primary spinal cord tumors, including ependymomas, pilocytic astrocytomas, and diffuse midline gliomas. The most common primary neoplasms of the spine are intradural extramedullary spinal meningiomas, whereas primary neoplasms of the leptomeninges are rare. Advances in molecular characterization of spinal cord tumors and recent clinical trials of these rare entities are expanding the repertoire of systemic therapy options for primary spinal cord neoplasms. Metastases to the spine most often affect the extradural space. Metastatic epidural spinal cord compression is a neurologic emergency that requires a rapid, multidisciplinary response to preserve neurologic function.

ESSENTIAL POINTS

Neurologists should understand the diagnostic approach to neoplasms of the spinal cord. Knowledge of the most common spinal cord neoplasms will allow for appropriate management and optimal patient care.

Diffuse Leptomeningeal Glioneuronal Tumor in Adults: Case Report and Literature Review

Introduction

Diffuse leptomeningeal glioneuronal tumor (DLGNT), a new addition to the 2016 World Health Organization (WHO) classification, is a rare childhood neoplasm presenting with disseminated leptomeningeal enhancement and an occasional intraparenchymal mass. Diagnosis is often impeded by infectious/immunological differentials, necessitating a biopsy to confirm the diagnosis. We report an adult male with DLGNT without hydrocephalus, which is rare in patients with cerebellar masses.

Case Presentation

A 56-year-old man presented with headaches, vertigo, diplopia, impaired hearing, and gait imbalance over 6 months. Magnetic resonance imaging showed a cystic right cerebellar mass with its leptomeningeal dissemination but without hydrocephalus. Cerebrospinal fluid analysis revealed elevated proteins with CD56-positive tumor cells. Cerebellar lesion biopsy verified the diagnosis of DLGNT (WHO Grade 3) with KIAA1549::BRAF fusion and 1p deletion. Radiotherapy was prematurely aborted due to clinical deterioration. The patient was subsequently discharged to palliative home care and lost to follow-up.

Conclusion

We conducted the first review of all 34 adult DLGNT cases, including ours (one of the oldest), hitherto published in the literature. The majority presented with signs and symptoms of increased intracranial pressure. 52.0% of adult DLGNT patients were alive at follow-up. DLGNT should be considered in the differential diagnoses of diffuse leptomeningeal enhancement in imaging. Further studies comparing pediatric and adult subgroups of DLGNT are needed to evaluate histopathological prognosticators and standardize therapy for both subpopulations.

Aggressive Diffuse Leptomeningeal Glioneuronal Tumor in a Pediatric Patient Presenting With Mismatch Repair Gene Mutations

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare primary central nervous system tumor. We present the case of a five-year-old male patient with a rapid progression of a thoracic DLGNT. Initial presentation and workup confirmed acute communicating hydrocephalus requiring a ventriculoperitoneal shunt. Cerebrospinal fluid analysis showed hyperproteinorrachia. Additional workup demonstrated an intramedullary mass at the conus medullaris associated with leptomeningeal enhancement. A T10-T12 laminoplasty with tumor resection was performed. Immunohistochemistry was positive for glial fibrillary acid protein and synaptophysin, with a negative epithelial membrane antigen. The tumor had a Ki67 proliferation index of 9%. Gene tumor analysis revealed the presence of the KIAA1549-BRAF gene fusion. The tumor expressed MSH6, MLH1, MSH2, and PMS2 mismatch repair gene mutations. Multiple subsequent shunt revisions were performed due to malfunction secondary to the hyperproteinorrachia. Follow-up studies showed extensive brain and spinal nodular cystic lesions associated with extensive leptomeningeal spread of disease. The patient received chemotherapy but died due to disease progression. This case report described a rapidly progressive and aggressive DLGNT in a pediatric patient presenting mismatch repair gene mutations. Due to hyperproteinorrachia, shunt revisions are frequently needed in these patients. Even though DLGNT pathology can depict a low-grade tissue, some tumors behave aggressively with minimal significant response to medical and surgical treatments. Mutations of mismatch repair genes MSH6, MLH1, MSH2, and PMS2 may be associated with more aggressive tumors.

Diffuse Leptomeningeal Glioneuronal Tumour

Diffuse leptomeningeal glioneuronal tumours (DL-GNT) are rare, with an unknown incidence but fewer than 100 cases reported since 2012. The clinical presentation is non-specific, ranging from abdominal to neurological symptoms. Presently, definitive radiological criteria aren't established, but some features, such as nodules, characteristic extension patterns and post-contrast leptomeningeal enhancement, are found to be prominent. We present the case of a 14-year-old male with an advanced case of DL-GNT, with MRI showing all the features of what is currently thought to be the typical radiological presentation. The patient is currently undergoing treatment but remains severely handicapped by the disease.

Rare Neuronal, Glial and Glioneuronal Tumours in Adults

Rare glial, neuronal and glioneuronal tumours in adults form a heterogeneous group of rare, primary central nervous system tumours. These tumours, with a glial and/or neuronal component, are challenging in terms of diagnosis and therapeutic management. The novel classification of primary brain tumours published by the WHO in 2021 has significantly improved the diagnostic criteria of these entities. Indeed, diagnostic criteria are nowadays multimodal, including histological, immunohistochemical and molecular (i.e., genetic and methylomic). These integrated parameters have allowed the specification of already known tumours but also the identification of novel tumours for a better diagnosis.