Flavio Giordano

Identification of Tumor-Specific Molecular Signatures in Intracranial Ependymoma and Association With Clinical Characteristics

PURPOSE To delineate clinically relevant molecular signatures of intracranial ependymoma. MATERIALS AND METHODS We analyzed 24 primary intracranial ependymomas. For genomic profiling, microarray-based comparative genomic hybridization (CGH) was used and results were validated by fluorescent in situ hybridization and loss of heterozygosity mapping. We performed gene expression profiling using microarrays, real-time quantitative reverse transcriptase polymerase chain reaction, and methylation analysis of selected genes. We applied class comparison analyses to compare both genomic and expression profiling data with clinical characteristics. RESULTS A variable number of genomic imbalances were detected by array CGH, revealing multiple regions of recurrent gain (including 2q23, 7p21, 12p, 13q21.1, and 20p12) and loss (including 5q31, 6q26, 7q36, 15q21.1, 16q24, 17p13.3, 19p13.2, and 22q13.3). An ependymoma-specific gene expression signature was characterized by the concurrent abnormal expression of developmental and differentiation pathways, including NOTCH and sonic hedgehog signaling. We identified specific differentially imbalanced genomic clones and gene expression signatures significantly associated with tumor location, patient age at disease onset, and retrospective risk for relapse. Integrated genomic and expression profiling allowed us to identify genes of which the expression is deregulated in intracranial ependymoma, such as overexpression of the putative proto-oncogene YAP1 (located at 11q22) and downregulation of the SULT4A1 gene (at 22q13.3). CONCLUSION The present exploratory molecular profiling study allowed us to refine previously reported intervals of genomic imbalance, to identify novel restricted regions of gain and loss, and to identify molecular signatures correlating with various clinical variables. Validation of these results on independent data sets represents the next step before translation into the clinical setting.

Diagnostic methods and treatment options for focal cortical dysplasia.

Our inability to adequately treat many patients with refractory epilepsy caused by focal cortical dysplasia (FCD), surgical inaccessibility and failures are significant clinical drawbacks. The targeting of physiologic features of epileptogenesis in FCD and colocalizing functionality has enhanced completeness of surgical resection, the main determinant of outcome. Electroencephalography (EEG)–functional magnetic resonance imaging (fMRI) and magnetoencephalography are helpful in guiding electrode implantation and surgical treatment, and high‐frequency oscillations help defining the extent of the epileptogenic dysplasia. Ultra high‐field MRI has a role in understanding the laminar organization of the cortex, and fluorodeoxyglucose–positron emission tomography (FDG‐PET) is highly sensitive for detecting FCD in MRI‐negative cases. Multimodal imaging is clinically valuable, either by improving the rate of postoperative seizure freedom or by reducing postoperative deficits. However, there is no level 1 evidence that it improves outcomes. Proof for a specific effect of antiepileptic drugs (AEDs) in FCD is lacking. Pathogenic mutations recently described in mammalian target of rapamycin (mTOR) genes in FCD have yielded important insights into novel treatment options with mTOR inhibitors, which might represent an example of personalized treatment of epilepsy based on the known mechanisms of disease. The ketogenic diet (KD) has been demonstrated to be particularly effective in children with epilepsy caused by structural abnormalities, especially FCD. It attenuates epigenetic chromatin modifications, a master regulator for gene expression and functional adaptation of the cell, thereby modifying disease progression. This could imply lasting benefit of dietary manipulation. Neurostimulation techniques have produced variable clinical outcomes in FCD. In widespread dysplasias, vagus nerve stimulation (VNS) has achieved responder rates >50%; however, the efficacy of noninvasive cranial nerve stimulation modalities such as transcutaneous VNS (tVNS) and noninvasive (nVNS) requires further study. Although review of current strategies underscores the serious shortcomings of treatment‐resistant cases, initial evidence from novel approaches suggests that future success is possible.

Subependymal giant cell astrocytoma (SEGA): Is it an astrocytoma? Morphological, immunohistochemical and ultrastructural study.

Subependymal giant‐cell astrocytoma (SEGA) is a rare intra‐ventricular low‐grade tumor which frequently occurs as a manifestation of tuberous sclerosis complex. The histogenesis of SEGA is controversial and its astrocytic nature has been doubted. First studies suggested the astrocytic nature of SEGA while several recent reports demonstrate its glio‐neuronal nature. In spite of this, in the recently revised WHO classification of the CNS tumors, SEGA has been still included in the group of astrocytomas. We studied nine tuberous sclerosis complex‐associated SEGAs. Patients were 1–18 years old. Eight patients (89%) had a solitary lesion located in the lateral ventricle close to of the head of the caudate nucleus, the remaining patient (11%) had two tumors, one located close to the head of the left caudate nucleus and the other in the central part of the right lateral ventricle. Histologically, tumors were composed of three types of cells: spindle, gemistocytic and ganglion‐like. Four tumors (44%) had a prominent vascularization and three (33%) showed an angiocentric pattern. Calcifications were observed in six cases (66%). By immunohistochemistry, the majority of the tumors were GFAP‐ (9; 100%), neurofilament‐ (8, 89%), neuron‐specific enolase‐ (9, 100%), and synaptophysin‐ (8; 89%) positive. Ultrastructural studies were performed on four cases. In all four there were glial cell processes filled with intermediate filaments. In one case dense core putative neurosecretory granules were appreciable. Our results emphasize the glio‐neuronal nature of SEGA. We suggest moving it into the group of mixed glio‐neuronal tumors under the denomination of subependymal giant cell tumor.

Papillary glioneuronal tumor radiologically mimicking a cavernous hemangioma with hemorrhagic onset

Papillary glioneuronal tumor is a recently identified low‐grade brain neoplasm classified as variant of ganglioglioma. Its salient morphological characteristics are the presence of pseudopapillary structures composed of blood vessels, often hyalinized, lined by uniform small astrocytes and a proliferation of neurocytic cells, eventually admixed with ganglioid and ganglion cells. We present a case of papillary glioneuronal tumor occurring in a 15‐year‐old female with an unusual hemorrhagic onset. The clinical, morphological and immunohistochemical features are discussed and the published literature is reviewed. This article proposes that papillary glioneuronal tumor should be included in the differential diagnosis of patients with tumoral related brain hemorrhage.

Co-occurring malformations of cortical development and SCN1A gene mutations

To report on six patients with SCN1A mutations and malformations of cortical development (MCDs) and describe their clinical course, genetic findings, and electrographic, imaging, and neuropathologic features.

Intrinsic epileptogenicity of gangliogliomas may be independent from co-occurring focal cortical dysplasia.

Gangliogliomas are a frequent cause of drug-resistant epilepsies in children. It remains unknown, however, whether gangliogliomas are intrinsically epileptogenic or if associated lesions contribute to their high epileptogenicity, i.e. associated focal cortical dysplasia (FCD). We report on a child operated twice for drug-resistant focal seizures symptomatic of a right temporal lobe lesion. Histological examination of the first, incomplete lesionectomy revealed tumor-associated FCD Type IIIb. The child was not seizure-free, and surface as well as intracerebral recordings were obtained during a second presurgical assessment. Histopathological examination of the second operation revealed a ganglioglioma. Intralesional EEG recordings from the ganglioglioma documented rhythmic bursts of fast activity suggesting that the high epileptogenicity of gangliogliomas is related to intrinsic epileptogenic activity.

The medical and surgical treatment of tumoral seizures: current and future perspectives.

Epilepsy surgery represents the main treatment option for epileptogenic brain tumors. Scalp video–electroencephalography (EEG) and magnetic resonance imaging (MRI) may suffice for defining lesional area and seizure‐onset zone in discrete, surgically resectable lesions. The choice of timing for surgery requires a multidisciplinary evaluation, especially in children, when a “wait and see” approach is chosen. Discordant electroclinical and neuroimaging data and an ill‐defined epileptogenic lesion require invasive investigations. A multimodal integrated approach may maximize the extent of resection while preserving cerebral function in the eloquent cortex. Radical removal of the tumor is the most important predictor of seizure freedom. Additional predictors include histopathology, age at surgery, duration of epilepsy, and seizure type. Patients with brain tumors are highly vulnerable in relation to the frequent drug‐resistance of seizures, the potential interactions between antiepileptic drugs (AEDs) and chemotherapeutic agents (CMTs), and the risk of AED‐related cognitive adverse events (24% higher than in the rest of the epilepsy population), in addition to brain damage resulting from tumor itself, surgery, and radiotherapy. No robust, randomized, controlled evidence supports the choice of AEDs for the treatment of seizures in patients with brain tumors. Newer AEDs have limited or no enzyme‐inducing profile, prevalent renal excretion, lower plasma protein binding and, consequently, fewer interactions with CMTs. Enzyme‐inducing AEDs can lower serum levels of concomitantly administered CMTs. Class I evidence suggests that in patients with brain tumors who do not have a history of seizures, prophylactic use of AEDs is neutral or ineffective.

O6- Methylguanine-DNA-Methyltransferase in Recurring Anaplastic Ependymomas: PCR and Immunohistochemistry

Abstract Ependymomas are the third most common brain tumor in children. The post surgical management is controversial. There are no convincing data on an effective role for chemotherapy. O6-Methylguanine-DNA-Methyltransferase (MGMT) is a DNA repair protein considered to be a chemosensitivity predictor. Hypermethylation of the MGMT gene promoter is an important cause of MGMT inactivation. We evaluated the MGMT gene promoter methylation and the immunohistochemical MGMT protein expression in 12 recurrent anaplastic ependymomas affecting children. Our purpose was to investigate the molecular rationale of the administration of alkylating agents to children affected by recurrent anaplastic ependymomas. All ependymomas lacked MGMT promoter hypermethylation and 9 (75%) showed high MGMT protein expression (>50% tumoral cells). Differences between different recurrences in the same patient were not observed. These results may indicate MGMT as a factor of chemoresistance to alkylating drugs in anaplastic ependymomas and support the uncertainties regarding the actual benefit of chemotherapy for patients with anaplastic ependymomas.

Overview of presurgical assessment and surgical treatment of epilepsy from the Italian League Against Epilepsy

The Commission for Epilepsy Surgery of the Italian League Against Epilepsy (LICE) presents an overview of the techniques and methodologies of presurgical evaluation and of the surgical treatment of epilepsies. This overview is the result of the experience developed in the past years in the major Italian centers where programs of epilepsy surgery have been established, and it has the aim of offering a quick and easy reference tool for those involved in the treatment of patients with epilepsy. The sharing of different experiences has the additional aim of conforming and disseminating the employed techniques as well as the methods of selection and evaluation of patients. The synthetic coverage of the main issues concerning the presurgical workup and the available surgical options will hopefully provide a framework that may integrate and develop the contributions of every single center, in one of the more complex, challenging, and dynamic areas of neurological sciences.

Epilepsy surgery in Neurofibromatosis Type 1

Epilepsy is relatively uncommon in patients with Neurofibromatosis Type 1 (NF1) and seizures are usually well controlled with antiepileptic treatment. However, pharmacoresistance has been reported in patients with NF1 and MRI evidence of malformations of cortical development or glioneuronal tumours. Available information on epilepsy surgery in NF1 is limited to a few patients with gliomas and glioneuronal tumours who underwent lesionectomies. We conducted a survey amongst 25 European epilepsy surgery centres to collect patients with NF1 who had undergone surgery for drug-resistant seizures and identified 12 patients from eight centres. MRI abnormalities were present in all patients but one. They were unilateral temporal in eight, bilateral temporal in one and multilobar or hemispheric in two. Seizures originated from the temporal lobe in ten patients, from the temporo-parieto-occipital region in one, and were bitemporal in one. One year after surgery eight patients were seizure free, one had worthwhile improvement and the remaining three had experienced no benefit. Postoperative outcome, available at 2 years in ten patients and at 5 years in three, remained stable in all but one whose seizures reappeared. Histology revealed dysembryoplastic neuroepithelial tumour (DNET) in five patients, hippocampal sclerosis in four, mixed pathology in one and polymicrogyria in one. No histological abnormality was observed in the remaining patient. Epilepsy surgery can be performed effectively in patients with NF1 provided a single and well-delimited epileptogenic zone is recognized. The high prevalence of DNETs in this series might suggest a non-fortuitous association with NF1.