Magnetic resonance imaging findings of mixed neuronal-glial tumors with pathologic correlation: a 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.

Negative or positive imaging: ganglioglioma in a boy with epilepsy

Ganglioglioma is a rare primary tumour of the central nervous system, which characteristically contain both neuronal and glial neoplastic components mainly in children and adolescents. The most common clinical presentation is refractory epilepsy. The imaging findings of ganglioglioma are obvious and varied. However, ganglioglioma with normal neuroimaging is rare. We report a 12-year-old boy presented with intractable focal epilepsy with normal CT and almost negative MRI. The epileptogenic focus was found to be located in the left posterior superior temporal gyrus by comprehensive evaluation including PET-CT imaging and stereo electroencephalography monitoring. The epileptogenic focus was resected, and the histological examination of the surgical specimen confirmed ganglioglioma. He was seizure-free at last follow-up 14 months after surgery.

Papillary glioneuronal tumor: a case report of the cerebral aqueduct and review of literature

Papillary glioneuronal tumour is an entity described as grade I neuronal-glial tumour by the World Health Organization. Headaches, seizures, vomiting, language or visual disturbances, and hemiparesis are the most common clinical findings. This tumour typically presents as cystic with enhancing mural nodule in the cerebral hemisphere. In this paper, we reported a case of a papillary glioneuronal tumour in a young adult whose magnetic resonance imaging revealed a solid tumour in the cerebral aqueduct. The tumour was totally resected surgically 13 years ago. The histological and immunohistochemical examination determined the diagnosis. No further therapy was necessary. Currently, the patient presents no neurologic signs or symptoms and there is no radiologic evidence of tumour relapse. The case of papillary glioneuronal tumour reported here displayed unusual location and radiologic features. The long duration of follow-up of this case with no tumour relapse enhances that the preferred management for this type of tumour is its total surgical resection.

Imaging manifestations of papillary glioneuronal tumors

To analyse the imaging findings of papillary glioneuronal tumors (PGNTs), in order to improve the accuracy of preoperative diagnosis of this tumor. The clinical and imaging manifestations of 36 cases of PGNT confirmed by pathology were analyzed retrospectively. A total of 17 males and 19 females, averaging 22.47 (± 11.23) years. Initial symptoms included epilepsy in ten, headache in seven, and others in 19 cases. 97.2% (35/36) of the lesions were located in the supratentorial area, and 80.5% (29/36) in the intraventricular or deep white matter adjacent to the lateral ventricles. Twenty-four of the lesions (66.7%) were mixed cystic and solid, four (11.1%) were cystic with mural nodules, four (11.1%) were cystic, and four (11.1%) were solid. Four cases of PGNT of cystic imaging showed a "T2-FLAIR mismatch" sign. 69.4% (25/36) had septations. Nine lesions (25%) were accompanied by edema, and 9 (25%) of the mixed cystic and solid lesions were accompanied by hemorrhage. Among the 18 patients who underwent computed tomography (CT) or susceptibility-weighted imaging (SWI), nine had lesions with calcification. PGNTs mostly manifest as cystic mass with mural nodules or mixed cystic and solid mass in the white matter around the supratentorial ventricle, and the cystic part of the lesion is mostly accompanied by septations. Pure cystic lesions may exhibit the sign of "T2-FLAIR mismatch". PGNT is rarely accompanied by edema but sometimes by calcification and hemorrhage. Patients often present with seizures, headaches, and mass effect symptoms.

Novel role of the synaptic scaffold protein Dlgap4 in ventricular surface integrity and neuronal migration during cortical development

Subcortical heterotopias are malformations associated with epilepsy and intellectual disability, characterized by the presence of ectopic neurons in the white matter. Mouse and human heterotopia mutations were identified in the microtubule-binding protein Echinoderm microtubule-associated protein-like 1, EML1. Further exploring pathological mechanisms, we identified a patient with an EML1-like phenotype and a novel genetic variation in DLGAP4. The protein belongs to a membrane-associated guanylate kinase family known to function in glutamate synapses. We showed that DLGAP4 is strongly expressed in the mouse ventricular zone (VZ) from early corticogenesis, and interacts with key VZ proteins including EML1. In utero electroporation of Dlgap4 knockdown (KD) and overexpression constructs revealed a ventricular surface phenotype including changes in progenitor cell dynamics, morphology, proliferation and neuronal migration defects. The Dlgap4 KD phenotype was rescued by wild-type but not mutant DLGAP4. Dlgap4 is required for the organization of radial glial cell adherens junction components and actin cytoskeleton dynamics at the apical domain, as well as during neuronal migration. Finally, Dlgap4 heterozygous knockout (KO) mice also show developmental defects in the dorsal telencephalon. We hence identify a synapse-related scaffold protein with pleiotropic functions, influencing the integrity of the developing cerebral cortex.

Anaplastic ganglioglioma in pregnancy a cause of cerebral edema and maternal death

Objectives

The true incidence of anaplastic ganglioglioma during pregnancy is extremely rare, very few cases have been reported in the literature.

Case presentation

This is a report of a case of anaplastic ganglioglioma diagnosed in pregnancy. The patient is a 23-year-old primigravida who presented at 19 weeks of gestation headache and a convulsive episode. Her workup revealed a rare cerebral tumor that progressed to a neurological decline and died during the postpartum period.

Conclusions

Anaplastic ganglioglioma is an aggressive counterpart of Glial tumors; in pregnancy they are rare and symptoms are nonspecific. The outcome for the mother in this case fatal and a protocol for these cases has not yet been reported.

Intraoperative consultation in the diagnosis of posterior fossa brain tumors following the 2016 WHO update

OBJECTIVE

Intraoperative crush/squash smear or frozen section consultation is routinely performed at several centers and offers rapid onsite assessment of tumor type and provides invaluable information to the neurosurgeons. The WHO classification of central nervous system neoplasms underwent a paradigm shift in 2016 with the incorporation of molecular data with the morphological features, such that several new entities came to be distinctly defined. With this paper, we present our experience at intraoperative consultation of brain tumors arising in posterior fossa and aim to apprise the pathologists with the spectrum of cytomorphologic appearances that can occur during such consultation and highlight the diagnostic dilemmas and pitfalls encountered in this setting.

METHODS

This is a retrospective observational study illustrating the salient morphological features of commonly encountered brain tumors arising in the posterior fossa (prototype example of each type) reported at our institute over a period of seven years. Both squash smears and rapid snap frozen section were prepared and stained with Toluidine blue and rapid hematoxylin and eosin (H&E) stains.

RESULTS AND CONCLUSIONS

While the majority of tumors at this location comprise of pilocytic astrocytoma, ependymoma, and medulloblastoma, some rare examples may also arise; common differentials must be considered and prudently excluded to arrive at the diagnosis which is crucial in guiding the neurosurgeon. Both squash smears and rapid frozen section should be prepared and complement each other for rapid on-site evaluation.

Distinguishing Focal Cortical Dysplasia From Glioneuronal Tumors in Patients With Epilepsy by Machine Learning

Purpose: We are aiming to build a supervised machine learning-based classifier, in order to preoperatively distinguish focal cortical dysplasia (FCD) from glioneuronal tumors (GNTs) in patients with epilepsy. Methods: This retrospective study was comprised of 96 patients who underwent epilepsy surgery, with the final neuropathologic diagnosis of either an FCD or GNTs. Seven classical machine learning algorithms (i.e., Random Forest, SVM, Decision Tree, Logistic Regression, XGBoost, LightGBM, and CatBoost) were employed and trained by our dataset to get the classification model. Ten features [i.e., Gender, Past history, Age at seizure onset, Course of disease, Seizure type, Seizure frequency, Scalp EEG biomarkers, MRI features, Lesion location, Number of antiepileptic drug (AEDs)] were analyzed in our study. Results: We enrolled 56 patients with FCD and 40 patients with GNTs, which included 29 with gangliogliomas (GGs) and 11 with dysembryoplasic neuroepithelial tumors (DNTs). Our study demonstrated that the Random Forest-based machine learning model offered the best predictive performance on distinguishing the diagnosis of FCD from GNTs, with an F1-score of 0.9180 and AUC value of 0.9340. Furthermore, the most discriminative factor between FCD and GNTs was the feature "age at seizure onset" with the Chi-square value of 1,213.0, suggesting that patients who had a younger age at seizure onset were more likely to be diagnosed as FCD. Conclusion: The Random Forest-based machine learning classifier can accurately differentiate FCD from GNTs in patients with epilepsy before surgery. This might lead to improved clinician confidence in appropriate surgical planning and treatment outcomes.

Glioneuronal tumors: clinicopathological findings and treatment options

Glioneuronal tumors are very rare CNS neoplasms that demonstrate neuronal differentiation, composed of mixed glial and neuronal cells. The majority of these lesions are low grade and their correct classification is crucial in order to avoid misidentification as ‘ordinary’ gliomas and prevent inappropriate aggressive treatment; nevertheless, precise diagnosis is a challenge due to phenotypic overlap across different histologic subtype. Surgery is the standard of therapeutic approach; literature concerning the benefit of adjuvant treatments is inconclusive and a globally accepted treatment of recurrence does not exist. Targetable mutations in the genes BRAF and FGFR1/2 are recurrently found in these tumors and could take a promising role in future treatment management.

Imaging of Neuronal and Mixed Glioneuronal Tumors

Neuronal and mixed glioneuronal tumors represent a group of neoplasms with varying degrees of neural and glial elements. Their age of presentation varies, but they are most commonly seen in children and young adults. With the exception of anaplastic ganglioglioma and other atypical variants, most lesions are low grade; however, they can have significant morbidity because of seizures, mass effect, or difficult to treat hydrocephalus. Although many tumors show overlapping clinical and imaging features, some have relatively distinctive imaging characteristics that may aid in narrowing the differential diagnosis. In this review, we discuss relevant clinical and pathologic characteristics of these tumors and provide an overview of conventional and advanced imaging features that provide clues as to the diagnosis.

Diffuse leptomeningeal glioneuronal tumor in a Chinese adult: a novel case report and review of literature

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare glioma tumor classified by the World Health Organization as a central nervous system tumor in 2016. DLGNT is most common in children and adolescents but is rare in adults. A 25-year-old male patient was admitted due to recurrent seizures. Head magnetic resonance imaging revealed lesions in the right temporal lobe, which were considered to be intracranial tumors with variable properties. The patient was admitted for surgical treatment. After admission, it was confirmed that seizures were associated with right temporal lobe lesions. Right temporal epileptogenic focus resection was performed by craniotomy. Immunohistochemistry revealed that tumor cells were reactive for oligodendrocyte transcription factor 2, synaptophysin, S100 proteins, and α-thalassemia mental retardation X-linked; and partially reactive for neuronal nuclei, glial fibrillary acidic protein, and nestin. The vascular wall was reactive for vimentin, CD34, CD31, and smooth muscle actin. Ki-67 was 4%. Molecular detection demonstrated 1p36 deletion, O⁶-methylguanine-DNA-methyltransferase methylation, and positive v-raf murine sarcoma viral oncogene homolog B mutation. DLGNT. The patient recovered well after surgery and received 54 Gy/27f radiotherapy without neurological dysfunction and seizures. In this study, onset age, tumor site, tumor increment coefficient, molecular detection, treatment methods, and prognosis of 54 patients were summarized from 19 studies. DLGNT patients are characterized by more singular tumor site, smaller volume, lower increment coefficient, and longer stable disease period. Patients with DLGNT may also have a longer stable condition in cases of molecular detection of 1p/19q deletion, or BRAF fusion.