Pathological spectrum of neuronal/glioneuronal tumors from a tertiary referral neurological Institute

Surgical treatment of pediatric low-grade glioma in developing countries

Pediatric low-grade gliomas constitute the most common brain tumors worldwide, though with some peculiarities in the presentation and surgical care in different parts of the world. The symptomatology in developing countries is likely to be over longer periods with a tendency to delayed diagnosis due to cultural, religious beliefs, manpower, and infrastructural deficits. Thus, the children present with large tumors with attendant morbidities and an increased risk of mortalities from surgery. Surgery is mainly by "general" neurosurgeons due to the paucity of trained pediatric neurosurgeons. The pre-operative imaging may be limited to anatomic MR imaging, and in some cases, CT scans, without expansive neuropsychological evaluation. The armamentarium available to the neurosurgeon may warrant large openings to access the tumor, and there may be limited possibility for intra-operative mapping of "eloquent" brain functions when this is deemed necessary. Complicating pre-operative acute hydrocephalus can result in two operations that further worsen the catastrophic spending associated with brain tumor surgeries in these climes. While these challenges appear daunting but certainly have not been enough to deter the "can do" spirit of neurosurgeons in developing countries, it is essential to strengthen the training of pediatric neurosurgeons in LMICs and provide a platform for the advocacy of better infrastructure for the surgical management of these tumors.

Establishment and Characterization of Brain Cancer Primary Cell Cultures From Patients to Enable Phenotypic Screening for New Drugs

Aim: Desmoplastic infantile ganglioglioma (DIG), is a rare tumor arising mainly during the first 2 years of life. Molecular characterization of these benign yet rapidly proliferating tumors has been limited to evaluating a few mutations in few genes. Our aim was to establish a live cell culture to enable the understanding of the cellular processes driving the non-malignant growth of these tumors.

Methods: Tumor tissue from a rare non-infantile 8-year-old female DIG patient was dissociated and digested using collagenase to establish live cultures. Both 2D monolayer and 3D neurospheres were successfully cultured and characterized for proliferative potential, intrinsic plasticity, presence of cancer stem cells and the expression of stem cell markers. Cells cultured as 3D were embedded as tissue blocks. Immunohistochemistry was performed in both tissue and 3D sections for markers including synaptophysin, vimentin, neurofilament and MIB-1. Mutation analysis by NGS was performed using a-100 gene panel.

Results: Using immunohistochemistry, the 3D cultures were shown to express markers as in the original DIG tumor tissue indicating that the spheroid cultures were able to maintain the heterogeneity found in the original tumor. Cells continued proliferating past passage 10 indicative of immortalization. Enrichment of cancer stem cells was observed in neurospheres by FACS using CD133 antibody and RT-PCR. Mutation analysis indicated the presence of germline mutations in three genes and somatic mutations in two other genes.

Conclusion: A spontaneous cell line-like cell culture with high percentage of stem cells has been established from a DIG tumor for the first time.

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.

Rosette-Forming Glioneuronal Tumor of the Fourth Ventricle in Children: Case Report and Literature Review

BACKGROUND

Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a rare World Health Organization (WHO) grade I neoplasm. Gross total resection (GTR) is the treatment of choice, and there is no firm evidence supporting other treatment options when GTR is not feasible.

CASE DESCRIPTION

We report a 6-year-old boy who, following an initial subtotal resection of a fourth ventricular RGNT, received an individualized chemotherapy protocol with vincristine, etoposide, and carboplatin for 3 cycles. The tumor was stable for 2 years after the completion of chemotherapy but then began to progress, at which point GTR was successfully performed. In addition, we completed a comprehensive literature review of RGNT cases. To date, a total of 104 cases have been reported, 33 of which are pediatric cases. Recurrence has been reported in only 7 cases of all ages (4 in the pediatric population). Radiotherapy has been used in several cases, but adjuvant chemotherapy has been reported only once following a recurrence.

CONCLUSIONS

We report a case of chemotherapy administration as a first-line treatment for a subtotally resected RGNT. Chemotherapy may be considered as an adjuvant therapy option for RGNT when GTR cannot be achieved. Furthermore, increased incidence of recurrence in the pediatric population may suggest that the tumor biology of RGNT in children differs from that in adults.

Systematic Analysis of Clinical Outcomes Following Stereotactic Radiosurgery for Central Neurocytoma

Central neurocytoma (CN) typically presents as an intraventricular mass causing obstructive hydrocephalus. The first line of treatment is surgical resection with adjuvant conventional radiotherapy. Stereotactic radiosurgery (SRS) was proposed as an alternative therapy for CN because of its lower risk profile. The objective of this systematic analysis is to assess the efficacy of SRS for CN. A systematic analysis for CN treated with SRS was conducted in PubMed. Baseline patient characteristics and outcomes data were extracted. Heterogeneity and publication bias were also assessed. Univariate and multivariate linear regressions were used to test for correlations to the primary outcome: local control (LC). The estimated cumulative rate of LC was 92.2% (95% confidence interval: 86.5-95.7%, p<0.001). Mean follow-up time was 62.4 months (range 3-149 months). Heterogeneity and publication bias were insignificant. The univariate linear regression models for both mean tumor volume and mean dose were significantly correlated with improved LC (p<0.001). Our data suggests that SRS may be an effective and safe therapy for CN. However, the rarity of CN still limits the efficacy of a quantitative analysis. Future multi-institutional, randomized trials of CN patients should be considered to further elucidate this therapy.

Central Neurocytoma: A Review of Clinical Management and Histopathologic Features

Central neurocytoma (CN) is a rare, benign brain tumor often located in the lateral ventricles. CN may cause obstructive hydrocephalus and manifest as signs of increased intracranial pressure. The goal of treatment for CN is a gross total resection (GTR), which often yields excellent prognosis with a very high rate of tumor control and survival. Adjuvant radiosurgery and radiotherapy may be considered to improve tumor control when GTR cannot be achieved. Chemotherapy is also not considered a primary treatment, but has been used as a salvage therapy. The radiological features of CN are indistinguishable from those of other brain tumors; therefore, many histological markers, such as synaptophysin, can be very useful for diagnosing CNs. Furthermore, the MIB-1 Labeling Index seems to be correlated with the prognosis of CN. We also discuss oncogenes associated with these elusive tumors. Further studies may improve our ability to accurately diagnose CNs and to design the optimal treatment regimens for patients with CNs.

Rosette-forming Glioneuronal Tumor: Rare Case Presented with Spontaneous Disappearance of Contrast Enhancement

This report presents rosette-forming glioneuronal tumor (RGNT) of the tectum in a 24-year-old woman in whom spontaneous disappearance of contrast enhancement (CE) on magnetic resonance (MR) imaging was observed during 9-year follow-up period before therapeutic intervention. MR imaging obtained 9 years ago when she first visited local hospital with headaches showed a mass of the brain stem with CE. Follow-up MR imaging showed disappearance of CE without tumor growth. Nine years later, she was admitted to our hospital with headache and nausea, due to obstructive hydrocephalus. She underwent endoscopic third ventriculostomy (ETV) and tumor biopsy. Histological study revealed RGNT. To our knowledge, this is the first report presenting that the RGNT may show spontaneous disappearance of CE without tumor growth. It is unclear what this phenomenon means, however, knowledge of this phenomenon may be helpful for correct diagnosis and for follow up of RGNT.

A peculiar histopathological form of dysembryoplastic neuroepithelial tumor with separated pilocytic astrocytoma and rosette-forming glioneuronal tumor components

Dysembryoplastic neuroepithelial tumors (DNTs) mostly display typical clinical, neuroimaging and histopathological features, but sometimes they reveal heterogeneous or non-specific morphology, which results in diagnostic dilemmas. We present a case of a young adult with longstanding, intractable epilepsy associated with a multinodular cystic lesion in the temporal lobe. The lesion consisted of morphologically different components. In particular, a few cortical nodules displayed a specific glioneuronal element with floating neurons typically found in DNT. Two large, well-circumscribed nodules were entirely composed of biphasic, piloid, astroglial patterns that corresponded strictly to a pilocytic astrocytoma. The well-defined areas, which contained numerous distinct neurocytic-like rosettes, were identical with rosette-forming glioneuronal tumors (RGNTs). This type of neurocytic rosette was widespread within the surrounding piloid background. Some solid nodules exhibited increased cellularity, oligodendroglioma-like elements and a focal ribbon cell arrangement. The lesion was associated with advanced reactive gliosis and foci of dysplastic changes in the adjacent cortex. The clinico-radiological and main histopathological features were consistent with a diagnosis of a complex variant of DNT composed of pilocytic and rosette-forming glioneuronal components. Although both piloid tissue and rosette-like formations have been occasionally mentioned in DNT lesions, the present case of DNT was unique in its well-circumscribed, separate pilocytic and RGNT nodules. We concluded that it represented an unusual, mixed pilocytic/RGNT variant of DNT.

Clinical, radiological, and pathological features of 16 papillary glioneuronal tumors

BACKGROUND

Papillary glioneuronal tumors (PGNTs) are a novel distinct intracranial neoplastic entity. In this study, the authors aimed to analyze the clinical, radiological, and pathological features of PGNT.

METHODS

Clinical charts and radiographs of 16 cases of PGNT surgically treated between 2006 and 2013 were retrospectively reviewed. Follow-up evaluations and a literature review were performed.

RESULTS

The study included nine males and seven females with a mean age of 23.8 years. The most common preoperative symptom was headache (68.8 %, 11 of 16 patients). Radiological results showed that the frontal lobe (25.0 %) was the most common portion of the brain involved, and 13 lesions (81.3 %) presented with cystic appearance with or without solid elements. All patients were misdiagnosed as non-PGNT tumors. Complete resection was achieved in 12 patients (75.0 %). Ki67 staining was positive in <1 % of cells present in eight lesions and varied in the other eight lesions, with a range of 1 % to 13 %. The mean follow-up duration was 56.2 months, and no recurrence was observed. Seventy-seven PGNTs (40 males, 51.9 %) have been reported, and 49 patients stained positive for Ki67/MIB-1. Of these cases, 28 (57.1 %) had positive staining rates of ≥1 %. In 51 patients for whom outcome information was available, six (11.8 %) exhibited recurrence, and the recurrence rates for complete resection and incomplete resection were 5.1 % and 33.3 %, respectively.

CONCLUSIONS

PGNTs displayed a wide spectrum of clinical and radiological phenotypes, and they were more frequently observed in the frontal lobe and in young patients without sex predilection. Fair outcomes could be achieved by complete resection. Although PGNT displayed indolent pathobiology, atypical appearances were observed. More patients and longer follow-up periods are needed to further elucidate the biological features of PGNTs.

Seizure characteristics and prognostic factors of gliomas

Epilepsy in neuroepithelial tumors is highly prevalent. Neurogliomas (dysembryoplastic neuroepitheliomas [DNETs] and gangliogliomas) have a seizure incidence of 80-100%, low-grade gliomas of 60-85%, and glioblastoma of 30-60%. With each type, the appearance of seizures is usually the presenting clinical symptom, and with neuroglial tumors often the only clinical sign. Tumor locations in the temporal and insular cortex are associated with a higher risk of developing epilepsy in both neuroglial tumors and low-grade gliomas. Focal seizures with or without alteration of consciousness and/or secondary generalization are common. Focal seizures with altered consciousness are present in 50-70% of neuroglial tumors, and secondarily generalized seizures in 70% of low-grade gliomas. Surgical treatment, particularly gross tumor resection, contributes strongly to seizure freedom, especially in neuroglial tumors. Refractory epilepsy is more common in low-grade gliomas, occurring in 30-35%. Recurrence or worsening of seizures is often associated with tumor recurrence in glioblastomas. Translational studies have revealed a strong prevalence of IDH1 enzyme mutation together with the presence of seizures and long-term survival in low-grade gliomas. Disturbances of glutamate metabolism occur both in low-grade tumors and glioblastomas, and provide insight into mutual cellular pathway abnormalities contributing to both seizure development and tumor growth. Likewise, the recent clinical observations on antitumor activity of the anticonvulsant valproic acid in glioblastoma now provide promising outlooks on single therapies that target both seizures and gliomas.

Fourth ventricle rosette-forming glioneuronal tumour in children: an unusual presentation in an 8-year-old patient, discussion and review of the literature

INTRODUCTION

Rosette-forming glioneuronal tumour of the fourth ventricle is a rarely described entity. While usually having an indolent course and hence classified as a WHO grade 1 tumour, the precise characteristics and risk of recurrence of this tumour are still unknown. In addition, the preferred treatment modality remains unclear.

DISCUSSION

We present a case of an 8-year old with an early recurrence of 9 months after undergoing a sub-total resection of her tumour. Following further resection, there was no tumour present on the 3-month follow-up. In order to better characterise this tumour entity, we performed a review of the available literature on the subject. We found that it mainly affected young adults and had a female predominance. While initially these tumours were described in the fourth ventricle, the current literature suggests that they may be found in a larger variety of sites within the brain and spinal cord. There are several reports of recurrence occurring between 9 months and 10 years following surgery. There is as yet no feature of the tumour that appears to predict the risk of recurrence.

CONCLUSION

This phenomenon warrants further examination to discover if there is a sub-section of tumours that is likely to recur, and until this is established, all patients should be followed up at regular intervals.

Mixed glioneuronal tumor: a dysembryoplastic neuroepithelial tumor with rosette-forming glioneuronal tumor component

Neuronal and mixed neuronal-glial tumors of the CNS show a wide spectrum of components. Here, we report an unusual case of brain tumor with combined histological features of dysembryoplastic neuroepithelial tumor (DNT) and rosette-forming glioneuronal tumor (RGNT) in a 23-year-old man. It arose in the left anterior cingulate cortex with a pseudo-polycystic appearance on neuroimaging. Histological features contained the "specific glioneuronal element" mimicking DNT and the components of distinct neurocytic rosettes with a center of neuropil islands and pilocytic astrocytoma resembling RGNT. Although the mechanisms of mixed glioneuronal tumor are far from being well-known, their co-existence might suggest a possible etiologic relationship between DNT and RGNT.

Neuropathology of temporal lobe epilepsy

Pathologic findings in surgical resections from patients with temporal lobe epilepsy include a wide range of diagnostic possibilities that can be categorized into different groups on the basis of etiology. This paper outlines the various pathologic entities described in temporal lobe epilepsy, including some newly recognized epilepsy-associated tumors, and briefly touch on the recent classification of focal cortical dysplasia. This classification takes into account coexistent pathologic lesions in focal cortical dysplasia.