Dysembryoplastic Neuroepithelial Tumor Research Articles

Dysembryoplastic neuroepithelial tumor with rapid recurrence of pilocytic astrocytoma component

Dysembryoplastic neuroepithelial tumor (DNT) rarely has aggressive behavior with recurrence. The authors describe a case of DNT with rapid re-growth and features of pilocytic astrocytoma. A 19-year-old girl presented with a 3-year history of complex partial seizure, which was presumably because of DNT located in the left parietal lobe. The tumor was resected, although a tiny residual lesion with cystic space enlarged with ring enhancement identified on MRI 14 days after surgery resulted in re-excision. The recurrent tumor was eventually proved to be predominantly composed of pilocytic astrocytoma. DNT is known to recur only rarely as a tumor with morphologically different components, and no cases of recurrent DNT with rapidly-growing pilocytic astrocytoma have hitherto been reported in the literature. This phenomenon may be histological "replacement" at recurrence.

Recurrence and histological evolution of dysembryoplastic neuroepithelial tumor: A case report and review of the literature

Studies of recurrent dysembryoplastic neuroepithelial tumors (DNTs) are distinctly rare. The present study reports the case of a 15-year-old female with a temporal lobe DNT, which recurred and transformed into an astrocytoma (WHO grade II) five years after an initial gross total resection (GTR). Furthermore, all the previous studies on recurrent DNT are reviewed. Although the majority of DNT cases demonstrate benign behavior, recurrent DNTs have been observed following a GTR of the tumor. Patients do not appear to benefit from post-operative adjuvant therapy, and inappropriate radiotherapy or chemotherapy may result in tumor recurrence or malignant transformation. The prognosis is favorable if a GTR of the recurrent tumor is achieved. The use of regular imaging examinations and the maintenance of a long-term follow-up is of importance following a tumor resection.

Brain Tumor Presenting as Somnambulism in an Adolescent

Sleepwalking is typically a benign and self-limited non-rapid eye movement parasomnia of childhood. We describe an unusual 15-year-old boyreferred to our sleep center for new-onset sleepwalking. An overnight polysomnogram was normal from a respiratory standpoint, but a concurrent extended electroencephalogram montage showed frequent epileptiform discharges from the right parietal-temporal region and two electroclinical seizures arising from the right-frontal-central-temporal region during sleep. Magnetic resonance imaging scan revealed a right parasagittal parietal region lesion consistent with a low-grade neoplasm, and surgical resection of the lesiondemonstrated a right parietal dysembryoplastic neuroepithelial tumor.Complex partial seizures and sleepwalking remitted completely with anticonvulsant therapy following surgery. This patient highlights the differential diagnosis ofnocturnal events appearing tobe typical parasomnias, especially when they arise abruptly at an older age.

Immunohistochemical Expression of Glypican-3 in Pediatric Tumors: An Analysis of 414 Cases

Glypican-3 (GPC3) is a proteoglycan thought to play an important role during development. Germline GPC3 mutations are seen in the rare Simpson-Golabi-Behmel syndrome (SGBS), which predisposes patients to Wilms tumor, hepatoblastoma, and neuroblastoma. While numerous adult tumors have been evaluated by immunohistochemistry for GPC3, no comprehensive assessment has been done in pediatric tumors. We therefore investigated GPC3 expression in 143 pediatric central nervous system (CNS) tumors and 271 non-CNS tumors. Among non-CNS tumors, GPC3 expression was seen in 9/9 (100%) hepatoblastomas, 4/6 (67%) malignant rhabdoid tumors, 5/13 (38%) Wilms tumors, 11/37 (30%) alveolar rhabdomyosarcomas, and 8/45 (18%) embryonal rhabdomyosarcomas. All 136 neuroblastomas, 14 Ewing sarcoma/primitive neuroectodermal tumors, and 11 synovial sarcomas were immunonegative for GPC3. Among CNS tumors, GPC3 had restricted expression, with positivity in 6/6 (100%) atypical teratoid rhabdoid tumors and 1/4 (25%) craniopharyngiomas. The remaining 136 CNS tumors-23 medulloblastomas, 21 pilocytic astrocytomas, 13 gangliogliomas, 12 ependymomas, 12 glioblastomas, 11 choroid plexus neoplasms, 10 diffuse astrocytomas (grade II/III), 10 meningiomas, 8 dysembryoplastic neuroepithelial tumors, 8 oligodendrogliomas, 3 craniopharyngiomas, 3 germinomas, and 2 neurocytomas-were entirely negative for GPC3. These results showed GPC3 positivity in a number of non-CNS tumors, with no consistent discrimination between tumors that were or were not associated with SGBS. Within the CNS, GPC3 positivity was limited to a small subset of CNS neoplasms and may thus serve as a useful positive diagnostic biomarker (P < 0.0001) in addition to negative INI1/BAF47/SMARCB1 staining to differentiate atypical teratoid rhabdoid tumors from other high-grade pediatric brain tumors.

Dysembryoplastic Neuroepithelial Tumor

Dysembryoplastic neuroepithelial tumors are rare, surgically curable, neuronal-glial neoplasms affecting young patients with intractable epilepsy. Its recognition is needed to avoid unnecessary adjuvant therapy. The authors reviewed the records of 15 patients with dysembryoplastic neuroepithelial tumors who underwent epilepsy surgery using intraoperative electrocorticography monitoring, including 8 males and 7 females (mean age, 15.8 years). Neuroimaging showed a predominantly intracortical location, the presence of septations, a triangular pattern of distribution, a lack of contrast enhancement, and an absence of peritumoral edema. Eleven cases were classified as complex type, 3 as simple type, and 1 as "nonspecific" type. Associated cortical dysplasia was found in 5 cases and leptomeningeal involvement in 1 case. Its immunophenotype suggested a pluripotential neuroepithelial origin. The mean follow-up was 37.5 months; 2 patients had tumor recurrence. Although they are generally benign neoplasms, recurrences sometimes occur. Complete resection of the tumor with the epileptogenic zone is important for a favorable outcome.

Surgical strategy and seizure outcome in dysembryoplastic neuroepithelial tumor

Objective Dysembryoplastic neuroepithelial tumor (DNET) is a rare intracranial tumor with drug-resistant epilepsy.The authors present a review of 18 patients who underwent surgical removal of a DNET to discuss the surgical strategy epilepsy outcome.Methods There are 18 DNET patients from Aprial 2004 to Aprial 2010,4 patients were lost to follow up.Medical records,neuroradiological images of all 14 patients were investigated.There were 10 male and 4 female patients.Age of patients ranged from 4 to 25 years,mean 10.3.We preferred lesionectomy and intraoperative electrocorticography concomitantly.After tumor removal,we would coagulate surrounding cortex with bipolar if there were still spikes or sharp waves on electrocorticography.Engel prognosis was recorded for every patient.Results Time of follow-up ranged from 24 to 96 months,mean 46.6 months.Tumor was removed totally in 12 cases,partially in 2 cases.Intraoperative ultrasound was used in five patients and found tumor omission in 1 among the 5 patients.Engel prognosis was Ⅰ grade in 12 patients whose tumor was removed totally,and complete antiepileptic drugs withdrawn was achieved in 11 out of 12 patients.The other two patients got Engel Ⅱ and Ⅳ prognosis respectively.Tumor residue didn't regrow in a follow-up time of 54,63 months respectively.Conclusion Lesionectomy and bipolar coagulation are effective for seizure control.Residual tumor is a significant risk factor for poor seizure outcome.Intraoperative ultrasound are recommended to make sure total removal.Electrocorticography should be routinely used before and after tumor removal for a better seizure outcome. Key words: Dysembryoplastic neuroepithelial tumor; Operation; Epilepsy

Surgical pathologic features of cerebral cortical lesions taken from 600 patients with intractable epilepsy

Objectives: To determine the scope of histopathological variation in lesions responsible for epileptogenesis, I retrospectively reviewed the features of surgical specimens taken consecutively from 600 patients with intractable epilepsy. Methods: The patients were divided into three groups on the basis of age at seizure onset: 94 patients with infantile onset (before 1year of age), 307 patients with juvenile onset (between 1 and 12years of age), and 199 patients with adolescent/adult onset (at 13years of age or beyond). Histological and immunohistochemical evaluations of the surgical specimens were performed. Results: In the infant group, seizure duration was significantly shorter than in the other groups, and malformations caused by abnormalities of cortical development, including focal cortical dysplasia (FCD) type IIa/b, tuberous sclerosis, hemimegalencephaly, and polymicrogyria were predominant, whereas in the juvenile and adolescent/adult groups, other lesions such as hippocampal sclerosis (HS), tumors, FCD type I, and vascular lesions were frequently observed. For patients with HS, seizure duration in the juvenile group was significantly longer than in the adolescent/adult group. FCD type IIIa was noted in nearly half of patient with HS in both juvenile and adolescent/adult groups. The causative tumors included dysembryoplastic neuroepithelial tumors, gangliogliomas, astrocytomas, and other glioneuronal and glial tumors. Conclusion: Various histopathological entities and types, showing clear predominance depending on the age at seizure onset, were observed in patients with epilepsy. These features appear to provide information on the pathomechanisms of the lesions and their clinical relevance in affected patients.

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.

Dysembryoplastic neuroepithelial tumor, a pure glial tumor? Immunohistochemical and morphometric studies

Dysembryoplastic neuroepithelial tumor (DNT) is a benign glioneuronal tumor, occurring in children and adolescents, typically associated with drug-resistant partial seizures. Pathologically, DNT is characterized by a specific glioneuronal element that is comprised of oligodendroglia-like cells (OLC) and floating neurons. The definition of DNT is currently controversial and the incidence of DNT varies among institutions. In this study we characterize the morphologic profiles of OLC and floating neurons by performing immunohistochemical and morphometric studies on seven cases of a simple form of DNT. While a majority of OLC was positive for oligodendrocyte transcription factor 2 (Olig2), only floating neurons and a few small cells were positive for neuronal nuclear antigens (NeuN). Double immunofluorescence studies revealed co-localization of Olig2 and galectin 3 in OLC, but no co-localization of Olig2 and NeuN. The distribution pattern of NeuN-positive nuclei within the tumor tissue was not different from that in the adjacent neural tissue. A section cut perpendicular to the cortex stained with NeuN showed a continuous laminar arrangement with the adjacent cortex. Densities of NeuN-positive nuclei from tumors embedded in the white matter were significantly lower than those from tumors in the gray matter. Our results suggest that the NeuN-positive small and large cells observed within the specific glioneuronal element are in fact entrapped granular and pyramidal cells within the cortex and that OLCs are essentially glial and not neuronal in nature. DNT is thus a pure glial tumor rather than a glioneuronal tumor, that is, the equivalent of non-infiltrating oligodendroglioma, grade I.

The value of repeat neuroimaging for epilepsy at a tertiary referral centre: 16 years of experience

Magnetic resonance imaging (MRI) is the investigation of choice for detecting structural lesions that underlie and may accompany epilepsy. Despite advances in imaging technology, 20-30% of patients with refractory focal epilepsy have normal MRI scans. We evaluated the role of repeated imaging with improved MRI technology - an increase in field strength from 1.5T to 3T and superior head coils - in detecting pathology not previously seen. Retrospective review of a large cohort of patients attending a tertiary epilepsy referral centre who underwent MRI at 1.5T (1995-2004) and subsequently 3T (2004-2011) with improved head coils. Scan reports were reviewed for the diagnoses and medical notes for the epilepsy classification. 804 patients underwent imaging on both scanners, the majority with focal epilepsy (87%). On repeat scanning at 3T, 37% of scans were normal and 20% showed incidental findings. Positive findings included hippocampal sclerosis (13%), malformations of cortical development (8%), other abnormalities (4%) and previous surgery (18%). A total of 37 (5%) relevant new diagnoses were made on the 3T scans not previously seen at 1.5T. The most common new findings were hippocampal sclerosis, focal cortical dysplasia and dysembryoplastic neuroepithelial tumour. These findings affected patient management with several patients undergoing neurosurgery. The higher field strength and improved head coils were associated with a clinically relevant increased diagnostic yield from MRI. This highlights the importance of technological advances and suggests that rescanning patients with focal epilepsy and previously negative scans is clinically beneficial.

Dysembryoplastic Neuroepithelial Tumors Share with Pleomorphic Xanthoastrocytomas and Gangliogliomas BRAFV600E Mutation and Expression

Pediatric cortical glioneuronal benign tumors mainly include gangliogliomas (GG) [differential diagnoses pilocytic astrocytomas (PA) and pleomorphic xanthoastrocytomas (PXA)] and dysembryoplastic neuroepithelial tumor (DNT). DNT include the specific form and the controversial non-specific form that lack the specific glioneuronal element. Our aims were to search for BRAF(V600E) mutation and CD34 expression in DNT, PXA, GG and PA to correlate BRAF(V600E) mutation with BRAF(V600E) expression and to evaluate their diagnostic and prognostic values. Ninety-six children were included. BRAF(V600E) mutation was studied by sequencing and immunohistochemistry; CD34 expression was analyzed by immunohistochemistry. BRAF(V600E) mutation was detected in PXA (60%), GG (38.7%), DNT (30%, including 3/11 specific and 3/9 non-specific forms) and PA (12.5%). BRAF(V600E) expression was recorded in PXA (60%), GG (45.2%) and DNT (30%). CD34 expression was recorded in PXA (60%), GG (58.1%), DNT (25%) and PA (12.5%). Neither CD34 expression nor BRAF(V600E) status was predictive of prognosis, except for PA tumors where CD34 expression was associated with a shorter overall survival. In conclusion, DNT shared with PXA and GG, BRAF(V600E) mutation and/or CD34 expression, which represent molecular markers for these tumors, and we recommend searching for CD34 expression and BRAF(V600E) mutation in all DNT, especially the non-specific forms.

Oligodendroglioma (WHO grade I) in a young epilepsy patient: A specific entity lying within the spectrum of dysembryoplastic neuroepithelial tumor?

We studied a frontal lobe subcortical cystic tumor that had been resected from a 13-year-old girl with a 3-year history of intractable partial seizure. Currently, more than 13 years after surgery, the patient remains recurrence-free and has no neurological deficits. Histological examination showed that the tumor was non-infiltrating and paucicellular with a mucinous matrix, and consisted of fairly uniform small cells with round to oval nuclei. Within the mucinous matrix, the tumor cells were often arranged in pseudorosettes around small blood vessels. Mitotic activity and necrosis were absent, with a Ki-67 labeling index of <1%. Based on the immunohistochemical and ultrastructural findings, the constituent tumor cells were considered to be those of oligodendroglioma, including mini-gemistocytes and gliofibrillary oligodendrocytes. No neuronal elements were identified. Features of cortical dysplasia (FCD Type 1) were evident in the cortex covering the lesion. The surrounding white matter also contained a significant number of ectopic neurons. The entire pathological picture appeared to differ somewhat from that of ordinary oligodendroglioma (WHO grade II). Considering the clinical and pathological features, the present unusual oligodendroglioma appeared to represent a previously undescribed form of oligodendroglioma (WHO grade I) lying within the spectrum of dysembryoplastic neuroepithelial tumor (DNT; WHO grade I). Simultaneously, the present oligodendroglioma also raises the question of whether or not oligodendrocyte-like cells of DNTs truly show neurocytic differentiation.

Dynamic changes in magnetic resonance imaging appearance of dysembryoplastic neuroepithelial tumor with or without malignant transformation

Dysembryoplastic neuroepithelial tumors (DNETs) have conventionally been regarded as benign and stable tumors and considered curable with surgery without adjunctive therapy. Recently, recurrent DNETs with or without malignant transformation have been described. The authors report 2 unusual cases of DNET: 1) an enlarging lesion that developed an enhancing component over the natural course of 4 years, and 2) a recurrent DNET that developed an enhancing component 10-11 years after gross-total resection. The patient in the first case was treated with subtotal resection and adjuvant radiochemotherapy; histological examination of the tumor led to the diagnosis of DNET, WHO Grade I, for the nonenhancing component and anaplastic oligodendroglioma, WHO Grade III, for the enhancing component. The patient in the second case was treated with repeat gross-total resection; the original tumor had been histologically diagnosed as DNET, and the nonenhancing and enhancing components of the recurrent tumor were diagnosed as simple and complex forms of DNET, respectively. These and previous reports suggest an aggressive subtype of DNETs. If follow-up MRI reveals progressive behavior, resection should be performed without delay. Additional radiochemotherapy is needed if the histological diagnosis demonstrates malignant transformation.

Atypical characteristics and behavior of dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors (DNET) are classically considered as benign, cortically based tumors that are stable. However, there were case reports that suggested DNET may not be as benign as previously thought. The purpose of our study was to identify atypical location, characteristics, and behavior of DNET in children. The MRI images of 51 patients with pathologically proven DNET were retrospectively reviewed. The following were assessed: tumor location, neuroimaging appearances including hemorrhage, calcification and edema, tumor growth preoperatively and after subtotal resection, tumor recurrence, malignant transformation, and metastatic seeding. Two (3.9 %) patients had intraventricular lesions, three (5.9 %) had associated edema, three (5.9 %) had calcifications, and one (2 %) had hemorrhage on preoperative CT and MRI. Sixteen of 51 (31.4 %) lesions exhibited enhancement post gadolinium administration. Six of 29 (20.7 %) preoperative lesions that had follow-up imaging were enlarging prior to surgery. In 6 of 18 (33.3 %) with subtotal resection, there was an increase in size of the residual tumor. Tumor recurrence at the surgical bed occurred in 3 of 30 (10 %) patients who had gross total resection. Two of 51 (3.9 %) cases developed secondary lesions distant to the primary tumor; the secondary lesions were within the lateral ventricles. In children, DNET may have atypical location, characteristics and behavior, including growth of primary or residual lesions and multifocal tumor. These findings emphasize the need for follow-up of patients with DNET post-resection.

Electrocorticographic–Histopathologic Correlations Implying Epileptogenicity of Dysembryoplastic Neuroepithelial Tumor

Based on intracranial-video electroencephalography (EEG), histopathological features, and postoperative seizure outcome, we elucidated the epileptogenicity in patients with dysembryoplastic neuroepithelial tumor (DNT). Five patients (P1–P5) pathologically diagnosed with DNT underwent intracranial-video EEG to identify the ictal onset zone and irritative zone. We evaluated the correlations of ictal onset zone and irritative zone with the magnetic resonance imaging-visible lesion (MRI-lesion) and their histopatho-logical features. Intracranial-video EEG located the ictal onset zone adjacent to the MRI-lesion margin in four patients with complex/simple forms of DNT subcategory, and on the MRI-lesion in P3 with a nonspecific DNT form. The irritative zone extended to surrounding regions of the ictal onset zone in all patients. Histopathologically, MRI-lesions were characterized by specific glioneuronal elements, whereas the ictal onset zone and irritative zone were represented with dysplastic cortex accompanying oligodendroglia-like cells in four (P1, P2, P4, and P5) of five patients. Cortical dysplasia was identified with typical histopathologic features in the irritative zone remote from the MRI-lesion in P5. P3, with a nonspecific form, indicated prominent component of dysplastic cortex with oligodendroglia-like cells scattered in the MRI-lesion. Lesionectomy of MRI-lesion with additional cortical resections (including the ictal onset zone and irritative zone) yielded postoperative seizure freedom (Engel Class I) in P3, P4, and P5, while P1 and P2 (with only lesionectomy) experienced postoperative residual seizure (Class II and III in each patient). Our results suggest the intrinsic epileptogenicity of DNT. The topographical correlation indicated that the dysplastic cortex accompanying oligodendroglia-like cells was more epileptogenic than the specific glioneuronal elements itself. Meticulous intracranial-video EEG analysis delineating the MRI nonvisible ictal onset zone and the irritative zone may yield better seizure outcome.

Epilepsy surgery of dysembryoplastic neuroepithelial tumors using advanced multitechnologies with combined neuroimaging and electrophysiological examinations.

PurposeWe report three cases of dysembryoplastic neuroepithelial tumor (DNT) with intractable epilepsy which were successfully treated with surgery.MethodsIn all cases, technology beyond the routine workup was critical to success. Preoperative magnetic resonance imaging, 18F-fluorodeoxyglucose positron emission tomography (PET), 11C-methionine-PET, interictal electroencephalography, and intraoperative electrocorticography were utilized in all patients. In individual cases, however, additional procedures such as preoperative magnetoencephalography (Case 1), diffusion tensor fiber tractography, a neuronavigation system, and intraoperative somatosensory-evoked potential (Case 2), and fiber tractography and the neuronavigation-guided fence-post tube technique (Case 3) were instrumental.ResultsIn all the cases, the objectives of total tumor resection, resection of the epileptogenic zone, and complete postoperative seizure control and the avoidance of surgical complications were achieved.ConclusionsDysembryoplastic neuroepithelial tumor is commonly associated with medically intractable epilepsy, and surgery is frequently utilized. As DNT may arise in any supratentorial and intracortical locations within or near the critical area of the brain, meticulous surgical strategies are necessary to avoid neurological deficits. We demonstrate in the following three cases how adjunct procedures using advanced multitechnologies with neuroimaging and electrophysiological examinations may be utilized to ensure success in DNT surgery.

Rosette-forming glioneuronal tumour of the fourth ventricle arising in the cerebellar hemisphere: diagnostic challenges including cytological features in intra-operative squash preparations

Rosette-forming glioneuronal tumour (RGNT) is an entity newly codified in the 2007 WHO classification of tumours of the central nervous system. RGNTs are rare and typically arise in the mid-line in the region of the fourth ventricle. Origin at other sites such as cerebellar hemisphere, spinal cord and supratentorial sites has been described. The tumour consists of distinct neurocytic and astrocytic components, the former featuring distinctive neuro-cytic rosettes and perivascular pseudorosettes, and the latter resembling pilocytic astrocytoma. An atypical site of presentation and a predominance of either the neurocytic or astrocytic components at intra-operative consultation present diagnostic challenges. The distinctive appearance of the tumour in intra-operative squash preparations is a clue to the diagnosis in this setting. We describe the case of a RGNT which arose in the left cerebellar hemisphere. The intra-operative squash preparations showed the neurocytic rosettes and pseudorosettes within a loose fibrillary and mucinous background. The biphasic nature of the lesion was manifest in the frozen section, but more apparent in subsequent tissue sections. The differential diagnoses of RGNT with oligo-dendroglioma, pilocytic astrocytoma, central and extraventricular neurocytoma and dysembryoplastic neuroepithelial tumour are discussed.

Dysembryoplastic neuroepithelial tumors: Epileptogenicity related to histologic subtypes

ObjectiveTo analyze the electroclinical features and the relationship between the epileptogenic zone (EZ), the tumor and focal cortical dysplasia (FCD) in the three histologic subtypes of dysembryoplastic neuroepithelial tumors (DNTs) (“simple”, “complex” and “non-specific forms”). MethodsWe analyzed electroclinical data from 78 patients (50 males; 3–54years) operated for intractable epilepsy due to a DNT. We compared EZ extent, defined by stereo-electroencephalography (n=33), with the tumor and FCD areas, in each DNT subtype. ResultsNon-specific forms (68%) and temporal location were predominant (73%). The main characteristics consisted of late childhood epilepsy onset (median 12years), drug-resistant partial seizures and EEG abnormalities concordant with tumor location. In all DNT subtypes, intrinsic epileptogenicity was demonstrated by intralesional recordings (n=30), displaying a depressed background activity interrupted by rapid spikes or polyspikes. EZ co-localized with the tumor in all simple and complex DNTs, but in only 1/3 of non-specific DNTs. The main discordance between the EZ and tumor extent was found in temporal non-specific DNTs associated with extensive FCD. ConclusionThese results are helpful when planning surgery for DNTs. SignificanceIntrinsic epileptogenicity characterizes all DNTs; however, the EZ differs according to histologic subtypes and is particularly widespread in non-specific temporal forms.

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.

Albumin storage in neoplastic astroglial elements of gangliogliomas

PurposeLow-grade neuroepithelial tumors are frequent neuropathological findings in patients with pharmacoresistant epilepsies. Little is known regarding epileptogenic mechanisms in this group of neoplasms with gangliogliomas (GG) as the most common entity. Presence of hemosiderin deposits in GG points to impairment of the blood-brain barrier (BBB). Therefore, we hypothesized a potential role of BBB dysfunction and astrocytic albumin uptake as potential epileptogenic factor in GG. MethodsPrussian blue staining and fluorescent double-immunohistochemistry with antibodies against albumin, GFAP, CD34 and GLUT-1 were used to analyze hemosiderin deposits and astroglial albumin accumulation in tumor and adjacent pre-existing brain tissue of GG (n=10) and several control groups, i.e. dysembryoplastic neuroepithelial tumors (DNT; n=5), focal cortical dysplasia with balloon cells (FCD IIb; n=10), astrocytomas WHO grade II (n=5) and clear renal cell carcinoma brain metastases (RCCM, n=6). ResultsOur results revealed strong hemosiderin deposits in GG. Intriguingly, we noted substantial albumin uptake exclusively in neoplastic glial cell components of GG and DNT, whereas no significant albumin was present in perilesional reactive astrocytes. Strikingly, we did not observe substantial albumin uptake in further controls. ConclusionGlial albumin uptake was restricted to long-term epilepsy associated, vasculature-containing tumors. Intratumoural BBB dysfunction in concert with subsequent accumulation of albumin by neoplastic glial cell elements represent a new putatively epileptogenic mechanism for long-term epilepsy-associated tumors.