Dysembryoplastic neuroepithelial tumor: a surgically curable tumor of young patients with intractable partial seizures. Report of thirty-nine cases

Surgical outcome of epilepsy patients evaluated with a noninvasive protocol

Surgery is now an accepted treatment for some medically intractable epilepsies. Presurgical evaluation is particularly important for the localization of the epileptogenic zone, which may necessitate sophisticated imaging techniques and intracranial electroencephalogram (EEG) recordings. If patients are carefully selected, however, successful results can be achieved with noninvasive evaluation methods. Seventy-seven patients were operated on for intractable seizures. All patients underwent EEG, neuropsychological, psychiatric, and magnetic resonance imaging investigations. Ictal EEG-video recording was performed in all nonlesional and in some lesional cases that had discordant data. Selective amygdalo-hippocampectomy was performed on patients with mesial temporal lobe epilepsy (MTLE), an extended or a limited lesionectomy was performed on patients with structural lesions, and a lesionectomy with deafferentation was performed on two patients with West syndrome. Electrocorticography was not used. Temporal lobe directed surgery was performed in 63.6% of the cases. The pathological examinations of all cases showed hippocampal sclerosis (HS) in 43%, tumor or tumor-like lesions in 36%, and cortical dysplasia in 5% of patients. After a mean follow-up of 17 months (range, 2-53), 75% of the patients were seizure-free with or without aura and 15% had a marked improvement, whereas 10% did not benefit from surgery. Neuropsychological outcome of patients with MTLE and HS also showed worthwhile results. Our patients, who were evaluated without pre- and perioperative intracranial recordings and other sophisticated techniques, had an outcome comparable to those in other series from more experienced centers. Our experience indicates that successful results, especially for patients with MTLE-HS and lesion-related epilepsies, can be obtained at centers with limited resources if the diagnoses and evaluation procedures are performed carefully.

Temporal lobe epilepsy surgery with limited resources: results and economic considerations

This study evaluates the surgical outcome of patients with medically refractory temporal lobe epilepsy (TLE) who underwent anterior temporal lobe lobectomy (ATL) based on data derived from noninvasive studies and assesses the economic costs entailed at a newly created epilepsy program in Chile. Seventeen ATL candidates underwent a presurgical evaluation. This included outpatient brain MRI and neuropsychological testing and inpatient scalp/sphenoidal prolonged video-EEG monitoring. There were 10 females and 7 males, with a mean age of 23.8 years and a mean duration of seizure disorder of 12 years. Patients with congruent data localizing the seizure focus to one anterotemporal region underwent ATL. Seven patients underwent a left-side ATL and 10 patients a right-side ATL. The histopathological findings showed a low grade tumor in six patients, hippocampal sclerosis in five, neuronal migration disorder in four, and cavernous angiomas in two patients. The mean follow-up period was 29.1 months. Seizure outcome was assessed with Engel's classification: class I, no seizures or only auras; class II, rare seizures; class III, >90% seizure reduction; class IV, <90% seizure reduction. Fifteen patients are now in class I, one patient in class II, and one in class IV. The total cost, including evaluation and surgery, was equivalent to US$ 5,020. Thus, well-selected TLE patients can derive maximal benefit from ATL after a noninvasive presurgical evaluation. This finding is of great significance for the creation of epilepsy surgery programs in developing countries.

Dysembryoplastic neuroepithelial tumor of the cerebellum and brainstem. Case report

The authors present a case in which dysembryoplastic neuroepithelial tumors (DNETs) occurred in the cerebellum and brainstem of a 44-year-old woman. A magnetic resonance image of the brain revealed multiple cystic lesions in the right cerebellar hemisphere, vermis, tonsil, and brainstem. Partial removal of the tumors was performed. There were gray multinodular gelatinous lesions on the cerebellar hemisphere. Histologically, the tumors exhibited areas of multiple microcystic nodules in the cerebellar white matter, which were composed of oligodendroglia-like cells (OLCs), astrocytes, and neurons. There were multiple, variable nodules in the lesions, lined by OLCs. The adjacent cerebellar cortex displayed dysplastic features. Reduction of granule neurons and dislocation of Purkinje cells into the molecular layer were observed. The pathological profile of this patient agrees with that described by Daumas-Duport, et al., as a "dysembryoplastic neuroepithelial tumor."

Clinicopathological findings in patients who have undergone epilepsy surgery in the first year of life

Epilepsy presenting early in childhood may be associated with a neurologically devastating clinical course and have significant implications for the child's development. There are limited published data regarding the clinicopathological features of patients who have undergone epilepsy surgery in the first year of life and the role such surgery may have in reducing seizure frequency. This study retrospectively reviews the clinicopathologic features of eight patients from a tertiary care setting who underwent surgery for epilepsy in the first year of life. Eight infants, including seven males and one female, underwent surgery for epilepsy at 3-11 months of age (median 7.5 months). Age at the time of seizure onset ranged from birth to 2 months. Epileptogenic foci were localized by electroencephalographic and radiographic studies to the right side in five patients and left side in three patients. Histopathological findings in excised tissues included cortical dysplasia (n = 7), hemimegalencephaly (n = 3), and Sturge-Weber syndrome (n = 1). Dysplasia was marked by abnormalities in cortical lamination and neuronal orientation (n = 7), neuronal cytomegaly (n = 6), increased molecular layer neurons (n = 5) and balloon cells (n = 2). One patient was known to have epidermal nevus syndrome. Two patients required additional surgery for continued seizures. At last known follow up, all but one patient, who died in the postoperative period, were alive with no or decreased seizures at postoperative intervals of 3-60 months (median 13 months). Surgery can potentially ameliorate epilepsy in patients less than 1 year of age. Most of the patients in this series had cortical dysplasia as the underlying pathology of their epilepsy.

So-called malignant and extra-ventricular neurocytomas: reality or wrong diagnosis? A critical review about two overdiagnosed cases

Central neurocytoma (CN) is described as a rare intra-ventricular benign neuronal tumor of the brain. Two primary tumors first diagnosed as malignant and extra-ventricular neurocytomas are reported here. Histologically, the tumor of the first patient, a forty-one-year-old man, consisted of monotonous cells with round nuclei, but no fibrillar background. The second tumor, in a nineteen-year-old girl, showed areas of moderately pleomorphic round cells, with numerous rosettes and ganglion cell differentiation, in an abundant fibrillary network. Both presented calcifications. Mitoses were more frequent in recurrences and spinal locations than in the primaries. All tumors stained strongly for synaptophysin, and GFAP was partly positive in the first case only. Patients received post-surgical radiotherapy and were still alive eight and six years, respectively, after initial surgery. The interpretation of atypical cases, such as ours is not easy: the diagnoses finally retained were oligodendroglioma in the first case and ganglioneuroblastoma in the second case. Furthermore, neurocytomas atypical either by their unusual topographical or histological presentation or by their poor prognosis, have been frequently entitled in this way on synaptophysin positivity. So, we were prompted to reassess the entity of CN, seventeen years after the first description, to re-appreciate the reality of anatomo-clinical variants and to discuss the value of synaptophysin positivity in these tumors. In conclusion, it seems preferable to individualize true classical CN, which has a favorable outcome, from so-called extra-ventricular, atypical and anaplastic, clinically malignant neurocytomas for which complementary treatment is required.

Dysembryoplastic neuroepithelial tumor: radiological findings (including PET, SPECT, and MRS) and surgical strategy

In order to elucidate the radiological features of dysembryoplastic neuroepithelial tumor (DNT), and to clarify the optimal surgical strategy for this tumor, the authors retrospectively analyzed 20 cases of DNT treated at our institution. Magnetic resonance (MR) imaging (all cases), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) (eight cases), ictal/interictal Tc99m-HMPAO single photon emission computed tomography (SPECT) (seven and five cases respectively) and proton magnetic resonance spectroscopy (1H MRS) (one case) were performed preoperatively. Invasive monitoring/intraoperative electrocorticography (ECoG) was performed in four cases in order to determine the epileptogenic zone. A well-demarcated lobulating tumor located in the cortical with/without subcortical area was the typical MR finding. 18F-FDG PET showed glucose hypometabolism in all cases. Ictal Tc99m-HMPAO SPECT showed hyperperfusion of the lesion in three cases and interictal Tc99m-HMPAO SPECT showed hypoperfusion of the lesion in one case. 1H MRS showed nonspecific findings. Gross total resection was performed in all cases. Histologically, associated cortical dysplasia was found in 11 cases. The mean duration of follow-up after surgery was 37.9 months, and the overall seizure free rate was 90%. Follow-up MR imaging was performed in 14 cases (mean duration of follow-up: 21.6 months) and showed no recurrence of tumor in any of these cases. Invasive monitoring/intraoperative ECoG and the presence of cortical dysplasia showed no significant relationship with seizure control rate (p = 1.25 and p = 1.62 respectively).

Dysembryoplastic neuroepithelial tumor: an immunohistochemical study with myelin oligodendrocyte glycoprotein

CONTEXT

The dysembryoplastic neuroepithelial tumor (DNT) is an uncommon lesion characterized by a heterogeneous population of neurons, astrocytes, and oligodendroglia-like cells (OLCs). The basic nature of the DNT and its constituent cells, particularly the OLCs, remains unresolved; some authors favor a neuronal origin, and others propose a glial or mixed origin for these cells.

DESIGN

We examined 11 DNTs with antibodies to myelin oligodendrocyte glycoprotein, a marker of mature oligodendrocytes.

RESULTS

All DNTs studied (7 from males, 4 from females; age range of patients, 2-37 years) were composed of varying proportions of neurons, astrocytes, and OLCs. Membrane or cytoplasmic immunoreactivity for myelin oligodendrocyte glycoprotein was found in many OLCs in 9 of 11 cases. The number of myelin oligodendrocyte glycoprotein-positive OLCs was variable: >75% of the OLCs were positive in 5 cases, 25% to 75% of the OLCs were positive in 2 cases, and <25% of the OLCs were positive in 2 cases.

CONCLUSION

These findings suggest that many of the OLCs represent mature oligodendrocytes and support the notion that DNTs are heterogenous lesions composed of multiple, mature cell types.

Magnetic resonance imaging in temporal lobe epilepsy: usefulness for the etiological diagnosis of temporal lobe epilepsy

With improvement in magnetic resonance (MR) imaging techniques, the ability to identify lesions responsible for temporal lobe epilepsy has increased. MR imaging has also enabled the in vivo diagnosis of hippocampal sclerosis. Brain tumors are responsible for 2-4% of epilepsies in adult population and 10-20% of medically intractable epilepsy. The sensitivity of MR imaging in the diagnosis of tumors and other lesions of the temporal lobe (vascular malformations, etc.) is around 90%. Both hippocampal sclerosis and other temporal lobe lesions are amenable to surgical therapy with excellent postsurgical seizure outcome. In this article, we characterize and underline distinguishing features of the different pathological entities. We also suggest an approach to reviewing the MR images of an epileptic patient.

Dipole analysis in a case with tumor-related epilepsy

In order to evaluate the effectiveness of presurgical dipole analysis of interictal spikes as a non-invasive technique for the determination of epileptogenic area, we compared the results of this method with those of electrocorticography (ECoG) localization in the diagnosis of a patient with tumor-related epilepsy. A preoperative MRI revealed a temporal lobe tumor on the right side. The individual dipoles estimated from the interictal spikes were located mainly in the anterolateral region of the right temporal lobe, although some were located in the mesial side. The ECoG recorded frequent spikes in the anterolateral region of the right temporal lobe consistent with the location estimated by dipole analysis. After surgery, the patient suffered from residual seizures. Therefore, the residual epileptogenic area was examined by dipole analysis using a four-layered head model instead of the previous three-layered head model. As a result, the dipole analysis was able to pinpoint the epileptic focus in the area directly adjacent to the resected area, and in the mesial temporal lobe. In conclusion, EEG dipole analysis appears to hold promise as a non-invasive presurgical evaluation technique for locating epileptogenic areas as well as for postsurgical evaluation of residual epileptic focus.

Positron emission tomography using [18F] fluorodeoxyglucose and [11C] l-methionine to metabolically characterize dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors are unique and benign congenital tumors occurring frequently in children and adolescents. Differentiation from other low-grade tumors is important for management. Five patients with confirmed dysembryoplastic neuroepithelial tumors were studied with positron emission tomography using glucose and protein metabolic uptake in an attempt to categorize these tumors metabolically. Functional brain mapping also was obtained to aid in operative management. Results of the study conclude that dysembryoplastic neuroepithelial tumors, although having similar neuroimgaing characteristics to other low-grade tumors, are distinguished by a unique metabolic profile. They are inactive tumors with no significant glucose or protein metabolic activity. The combination of preoperative positron emission tomographic metabolic studies with functional brain mapping allowed for prediction of tumor type, defined eloquent areas of cortical function, and improved approach and resection of the tumors with minimal risk of neurologic impairment.

Evidence for developmental precursor lesions in epilepsy-associated glioneuronal tumors

The etiology and pathogenesis of epilepsy-associated local lesions remain largely unknown. Histopathologically, the most frequent lesions comprise gangliogliomas and glioneuronal malformations, i.e., hamartias or hamartomas, with a preferred location in the temporal lobe of young patients. A characteristic histopathological admixture of glial and neuronal elements, the focal appearance and the benign clinical behaviour suggest a malformative nature. So far, no molecular genetic alterations specifically involved in the pathogenesis of these glioneuronal lesions have been identified. However, immunohistochemical analysis revealed distinct distribution patterns of oncofetal antigens. The embryonic form of the neural cell adhesion molecule is present within glioneuronal hamartias, indicating an early migrational disorder. Recently, we have observed immunoreactivity for the stem cell marker CD34 in the majority of gangliogliomas and glioneuronal hamartomas. Based on these findings, we propose a common origin of gangliogliomas and glioneuronal hamartomas from a bipotent precursor that undergoes abnormal glioneuronal development.

Bcl-2 and Bcl-X expression in gangliogliomas

Bcl-2 and bcl-xL are proteins known to inhibit cell death (apoptosis). Expression of these proteins in gangliogliomas has not been extensively examined. This study retrospectively evaluates bcl-2 and bcl-x immunostaining in paraffin-embedded materials in gangliogliomas. Twenty-nine gangliogliomas in 17 males and 12 females, age 2.5 to 47 years (mean, 20.7 years), were studied. Nineteen tumors were situated primarily in the temporal lobe. All but three patients presented with seizures ranging from 3 months to 28 years' duration (mean, 11.1 years) before surgery. All tumors histologically were comprised of an atypical neuronal component and a glioma component, which most frequently resembled a low-grade astrocytoma. Cortical dysplasia was observed adjacent to eight tumors. MIB-1 (marker of cell proliferation) labeling indices (percentage of positively staining tumor cell nuclei) ranged from 0 to 7.7 (mean, 0.8). bcl-2 staining was observed in 25 tumors (86%); neuronal staining was present in 24 cases (83%), and glial cell staining in 21 tumors (72%). Bcl-xL staining was only observed in eight gangliogliomas (28%); in all eight tumors (28%), neuronal staining was seen, and focal glial cell staining was present in two cases (7%). Four tumors (14%) did not stain with either bcl-2 or bcl-xL. There appeared to be no relationship between MIB-1 immunostaining and staining with bcl-2 or bcl-xL. bcl-2 expression by immunohistochemistry was observed more frequently than bcl-xL in gangliogliomas. Expression of these proteins may reflect abnormalities of apoptosis, which could play a role in the survival of cells that may be involved in the development of gangliogliomas.

Clinical aspects and biological bases of drug-resistant epilepsies

The definition of drug-resistant epilepsy (DRE) is elusive and still controversial owing to some unresolved questions such as: how many drugs should be tried before a patient is considered intractable; to which extent side-effects may be acceptable; how many years are necessary before establishing drug resistance. In some cases, the view of epilepsy as a progressive disorder constitutes another important issue. Despite the use of new antiepileptic drugs (AEDs), intractable epilepsy represents about 20-30% of all cases, probably due to the multiple pathogenetic mechanisms underlying refractoriness. Several risk factors for pharmacoresistance are well known, even if the list of clinical features and biological factors currently accepted to be associated with difficult-to-treat epilepsy is presumably incomplete and, perhaps, disputable. For some of these factors, the biological basis may be common, mainly represented by mesial temporal sclerosis or by the presence of focal lesions. In other cases, microdysgenesis or dysplastic cortex, with abnormalities in the morphology and distribution of local-circuit (inhibitory) neurons, may be responsible for the severity of seizures. The possible influence of genes in conditioning inadequate intraparenchimal drug concentration, and the role of some cytokines determining an increase in intracellular calcium levels or an excessive growth of distrophic neurites, constitute other possible mechanisms of resistance. Several hypotheses on the mechanisms involved in the generation of DRE have been indicated: (a) ontogenic abnormalities in brain maturation; (b) epilepsy-induced alterations in network, neuronal, and glial properties in seizure-prone regions such as the hippocampus; (c) kindling phenomenon; (d) reorganization of cortical tissue in response to seizure-induced disturbances in oxygen supply. Such hypotheses need to be confirmed with suitable experimental models of intractable epilepsy that are specifically dedicated, which have until now been lacking.

Histological heterogeneity of dysembryoplastic neuroepithelial tumour: identification and differential diagnosis in a series of 74 cases

AIMS

In a retrospective study of resected specimens from 416 patients being treated for long-standing epilepsy, 74 cases of dysembryoplastic neuroepithelial tumour (DNT) were encountered that were all characteristically composed of small round oligodendroglia-like cells (OLC), astrocytes and mature neurones in varying proportions. The architectural patterns, histological, immunohistochemical and ultrastructural features and results of cell proliferation studies and postoperative follow-up are described to facilitate the identification of DNT and to differentiate it from other intrinsic neoplasms that commonly present with seizures.

METHODS AND RESULTS

The tumours presented with early onset of seizures, at a median age of 7 years, without the signs of raised intracranial pressure. A majority of the lesions were located in the temporal lobe (n = 59), with fewer cases in the frontal (n = 8), parietal (n = 6) and occipital lobes (n = 1), and ranged in size from 10 to 70 mm; 33 were cystic. Histologically three types could be distinguished, multinodular, solitary nodular and diffuse. The first type (37.8%) had the features of a typical DNT with multinodular architecture and mixed cellular composition. The second type (33.8%) consisted of a solitary nodule, while the third (28.4%) was a diffuse tumour, both composed of a similar mixture of cells as the multinodular DNT. The lesions were seen in the neocortex and white matter and tumours in the temporal lobe often involved the amygdala and hippocampus. The presence of myxoid matrix, microcystic change, calcification and leptomeningeal involvement were common. Dysplastic neurones at the periphery of the tumour and abnormalities in cortical lamination in the adjacent neocortex were found in about one-third of the resections. Rare mitotic figures were encountered in eight of the tumours and necrosis was found in two. Immunocytochemistry for glial fibrillary acidic protein (GFAP) and neuronal markers neuron-specific enolase, synaptophysin and neurofilament (RT 97) assists in establishing the diagnosis, highlighting the astrocytic and neuronal components, and the OLC, by the absence of expression of GFAP. Electron microscopy showed that in some cases OLC show neuronal differentiation. Although the proliferating cell nuclear antigen labelling index varied between 0 and 45.5%, 20 of the 51 tumours stained failed to express the antigen, in keeping with the indolent nature of this neoplasm. The response to surgery was excellent; none of the tumours have recurred, and the control of seizures remained good.

CONCLUSIONS

Despite some histological heterogeneity, the clinical and pathological features and indolent biological behaviour indicate that these tumours constitute a single distinct entity. The spectrum of morphological appearances of DNT is broader than has been previously reported, the recognition of which is needed to avoid unnecessary neoadjuvant therapy.

Cerebral neoplasms in adults

MRI plays a critical role in the diagnosis, management, and follow-up of adult supratentorial neoplasms. However, there is considerable overlap in the imaging findings of these lesions. New imaging methods, such as functional MRI, diffusion imaging, and spectroscopy may further improve diagnostic specificity and surgical management. Knowledge of the pathogenesis of these tumors, imaging characteristics, and available novel imaging tools will aid the radiologist in making meaningful contributions in the evaluation and treatment of these lesions.

Linear epidermal nevus and nevus sebaceus syndromes: a clinicopathologic study of 3 patients

BACKGROUND

Linear epidermal nevus syndrome and linear sebaceus nevus syndrome are rare neurocutaneous syndromes characterized by epidermal nevi, epilepsy, and mental retardation. Pathologic descriptions of the central nervous system findings in such patients are rare.

DESIGN

We examined the clinicopathologic features of 2 patients with linear epidermal nevus syndrome and 1 with nevus sebaceus syndrome who underwent surgical resections for chronic epilepsy in a tertiary referral center with a high volume of epilepsy surgery.

RESULTS

Patients included 3 females, aged 11 months (patient 1), 8 years (patient 2), and 2 1/2 years (patient 3) at the time of surgery. The duration of seizures prior to surgery was 11 months, 6 years, and 28 months, respectively. Two patients had epidermal nevi involving the head region (patients 1 and 3), and 1 had a nevus sebaceus of Jadassohn (patient 2); patient 2 had a choristoma, and patient 3 had a dermoid cyst in the eye region. Patient 1 demonstrated hemimegalencephaly radiographically. Histologic examination of resected cortical tissue in patients 1 and 2 demonstrated severe diffuse cortical dysplasia characterized by a disorganized cortical architectural pattern, a haphazard orientation of cortical neurons, and increased molecular layer neurons. Gyral fusion was seen in patient 1. Pial glioneuronal hamartomas were observed in patient 1. Prominent cortical astrocytosis was seen in patients 1 and 2, and foci of microcalcification were evident in patient 1. Cortical dysplasia was milder in patient 3 and consisted of an increased number of molecular layer neurons. Neuronal heterotopia was observed in all 3 patients.

CONCLUSION

The spectrum of neuronal migration abnormalities in the setting of these syndromes may be variable in terms of its histologic phenotypic manifestations.

Dysembryoplastic neuroepithelial tumor

Dysembryoplastic neuroepithelial tumors (DNTs) were first described in 1988. A DNT is a cortical tumor that produces enlargement of a gyrus, forming a megagyrus that exceeds the normal thickness of the cortex. This tumor is generally seen in young patients with a long-standing history of drug-resistant and disabling seizures mostly of the complex partial type. No neurological deficits are found between the interictal periods in the majority of the reported cases. A general agreement exists over the clinical and radiological manifestations of a DNT as well as the benign biological behavior. Two pathological variants of DNT have been recognized: the single form, composed only of the so-called specific glioneuronal element, and the complex form that additionally shows glial nodules and foci of cortical dysplasia. Nevertheless, and despite the benign biological course, nuclear atypias, cellular monstruosities, foci of necrosis and mitosis can also be found. Surgical eradication of the tumor will usuallly have a good prognosis, without recurrences and with a positive control to seizure-free clinical outcome. Controversy continues to exist over a hamartomatous or a neoplastic origin of this lesion. The DNT has been placed among the neuronal and mixed neuronal-glial neoplasms in the revised World Health Organization (WHO) brain tumor classification, a category that includes the gangliogliomas and the central neurocytomas. Ultrastructural studies and immunostaining techniques may suggest that these three lesions represent different spectrums of the same condition. This paper reviews the most recent publications to offer a better understanding of DNTs and their implications in diagnosis and management.

Dysembryoplastic neuroepithelial tumors: nonspecific histological forms -- a study of 40 cases

OBJECTIVE

To demonstrate that DNTs include a large morphological spectrum of tumors that cannot be histologically distinguished from conventional categories of gliomas.

METHODS

All tumors from patients who underwent epilepsy surgery in Sainte-Anne hospital (Paris) that histologically resembled gliomas and did not conform to current histological criteria for DNTs or gangliogliomas were entered in the study.

RESULTS

According to the WHO histological classification, the 40 tumors resembled: pilocytic astrocytomas (4 cases), astrocytomas (16 cases), anaplastic astrocytoma (1 case), oligodendrogliomas (10 cases), oligo-astrocytomas (8 cases) or anaplastic oligo-astrocytomas (1 case). However foci of cortical dysplasia could be observed in 47% of the cases. Clinical presentation and imaging features were strikingly similar to that observed in typical DNTs. Although surgical removal was incomplete in 28% of the cases and none of the patients underwent chemo or radiotherapy, none of the tumors recurred (mean follow-up: 7 years). Moreover, serial preoperative imaging in 26 patients (mean follow-up: 4.5 years) demonstrated that these lesions were perfectly stable.

CONCLUSIONS

Whatever the histological appearance of a glial tumor, the diagnosis of DNT must be considered when all the following criteria are associated: (1) partial seizures, with or without secondary generalization, beginning before the age 20 years, (2) no neurological deficit or stable congenital deficit, (3) cortical topography of the lesion as better demonstrated by MRI and (4) no mass effect on imaging.

Primary brain tumors in children under age 3 years

During the period from 1966 to 1996 the authors analyzed the clinicopathological characteristics of 46 cases of histologically verified primary brain tumors with symptomatic onset during the first 3 years of life. The patient group included 27 males and 19 females. There were 14 patients during the first year, 13 during the second year, and 19 during the third year. Supratentorial tumors (60.9%) were more common than infratentorial tumors. Histologically, neuroepithelial tumors predominated. The incidence of ependymal tumors, particularly malignant ones, and of neuronal/mixed neuronal-glial tumors was higher than in previous reports. Congenital brain tumors, those occurring within 2 months after birth, or tumors of dysplastic origin comprised 42.9% of the tumors that developed within 1 year of birth. At the onset, macrocephaly, failure to thrive, and seizures were prominent symptoms or signs in the younger patients. Focal neurological deficits and increased intracranial pressure predominated in the older patients. All but one patient underwent surgical treatment, and 17 patients received adjuvant therapy after surgery. The prognosis was mainly related to the histology of the malignancy. The outcome of medulloblastomas was poor. The quality of life of surviving patients was relatively good, 77.8% having better performance status (PS) than the Eastern Cooperative Oncology Group PS 2.

Brain tumors in surgical neuropathology of intractable epilepsies, with special reference to cerebral dysplasias

Surgical specimens from 30 patients (13 males and 17 females) with intractable epilepsy with brain tumors and allied lesions were histopathologically examined: 4 of nonneurogenic origin (1 angiolipoma with cortical dysplasia and 3 cavernous hemangiomas), 2 low-grade fibrillary astrocytomas, 1 pleomorphic xanthoastrocytoma, 3 pilocytic astrocytomas with nuclear polymorphism, 1 oligoastrocytoma, 9 gangliogliomas, 3 gangliogliomatous lesions combined with tuberous sclerosis-like dysplastic changes, and 7 undetermined lesions suspected of being mixed glioma, dysembryoplastic neuroectodermal tumor (DNT), or dysplasia. They were all located supratentorially: in the temporal lobe in 21, frontal lobe in 6, and parietooccipital lobe in 3. The age of onset was under 20 years in most patients. Some kinds of dysplasias, such as focal cortical dysplasia, glioneuronal heterotopia, and clustered neurons in the hippocampus and amygdaloid nucleus, were combined in 11 cases, especially those with age of onset under 10 years. Pilocytic astrocytoma-like features were seen in 5 of the gangliogliomas and 3 of the undetermined lesions, and DNT-like features in 2 of the former and 3 of the latter. Gangliogliomas, pilocytic astrocytomas, mixed gliomas, DNTs, and dysplasias may be closely inter-related in the development of intractable epilepsies of young patients.

Surgical management of pediatric tumor-associated epilepsy

Brain tumors are a common cause of seizures in children. Early surgical treatment can improve seizure outcome, but controversy exists regarding the most appropriate type of surgical intervention. Some studies suggest tumor resection alone is sufficient, while others recommend mapping and resection of the surrounding epileptogenic foci to optimize seizure outcome. To address this issue, we reviewed the charts of 34 pediatric patients aged 18 months to 20 years with medically intractable epilepsy and primary brain tumors. The average age at operation was 12.6 years, and patients had seizures for an average of 6.4 years. The majority of tumors were located in the temporal lobe. Seventeen patients, because of tumor location near an eloquent area, underwent extraoperative mapping using subdural electrode grids prior to definitive tumor resection. Fourteen of these patients had a gross total tumor resection, yet only two had a distinct zone of ictal onset identified and resected. The remaining 17 patients had tumors either in the nondominant hemisphere or far removed from speech-sensitive areas, and therefore did not undergo extraoperative subdural electroencephalograph mapping. Fourteen of these patients also had a gross total tumor resection, while none had intraoperative electrocorticography to guide the resection of additional nontumoral tissue. Overall, of the 28 patients treated with a gross total tumor resection, 24 (86%) are seizure free, while the other four are significantly improved. Of the six patients who had a subtotal tumor removal, five have persistent seizures. The mean follow-up was 3.6 years. We conclude that in children and adolescents, completeness of tumor resection is the most important factor in determining seizure outcome. The routine mapping and resection of epileptogenic foci might not be necessary in the majority of patients. As a corollary, the use of subdural electrode grids in pediatric patients with tumor-associated epilepsy should be limited to cases requiring extraoperative cortical stimulation for localization of nearby eloquent cortex.

Papillary glioneuronal tumor: a new variant of mixed neuronal-glial neoplasm

We describe the clinicopathologic features of nine cases of a unique papillary glioneuronal tumor (PGNT) exhibiting astrocytic as well as extensive and varied neuronal differentiation. The four male and five female patients studied ranged in age from 11 to 52 years (mean 27.7 years). They either presented with mild neurologic symptoms or were asymptomatic. Magnetic resonance imaging showed demarcated cystic, 1.5-cm to 7-cm contrast-enhancing masses; five involved the temporal lobe, two the parietal, and two the frontal. All but one were totally resected. No recurrence was noted despite a follow-up period of 3 years. Two microscopic components were evident: 1) compact pseudopapillae composed of hyalinized vessels covered by a single layer of glial fibrillary acid protein (GFAP)-positive astrocytes and 2) synaptophysin-positive neuronal cells of varying size, including neurocytes, ganglioid cells, and ganglion cells within neuropil. Immunostains for chromogranin-A were negative, as was in situ hybridization for chromogranin-A mRNA. Ultrastructurally, neuronal cells featured microtubule-containing processes and aberrant synaptic terminals, but dense core granules were rare. Overall, cellularity was moderate and atypia was minimal. No mitotic activity or necrosis was noted. The proportions of the two components varied, but essential morphologic findings were identical in all cases. In that the clinical, radiographic, and morphologic characteristics of PGNT are distinctive, it appears to represent a previously undescribed form of mixed neuronal-glial tumor of the central nervous system.

Pathologic basis of the symptomatic epilepsies in childhood

The epilepsies in childhood are classified as primary (or idiopathic) and secondary (or symptomatic). The primary epilepsies account for two thirds of all childhood epilepsies and are presumed to be genetically determined. In the remaining one third of cases, a neuropathologic lesion can be identified. This paper summarizes the etiologies of the symptomatic epilepsies. They are classified according to the pathologic processes; malformative, metabolic, neoplastic and phakomatoses, hypoxic-ischemic, infectious, and of unknown pathologic process.

[Dysembryoplastic neuroepithelial tumor. An epidemiological study from a single institution]

The true incidence of dysembryoplastic neuroepithelial tumor (DNT) is unknown. Variable estimations have been advanced according to the type of recruitment of patients. In series of patients with tumors who were operated on for pharmacoresistant epilepsy, the rates varied widely, from 5% to 87%. Among 600 pediatric tumors in a series, 9 DNT (1.5%) were found. Since DNT was identified only in 1988, we reviewed our cases (1975-1991) of gangliogliomas (n = 25), oligoastrocytomas (n = 9), temporal oligodendrogliomas (n = 11), temporal astrocytomas grade II (OMS 1993) (n = 44) irrespective to age, as well as all astrocytomas grade II (n = 61) and oligodendrogliomas (n = 10) in patients up to 20 years of age. Seven DNT were encountered. Four cases had been formerly diagnosed as gangliogliomas and 3 as astrocytomas grade II. From 1992 on, 4 more DNT were diagnosed, making up a total of 11 cases. Eight patients were under age 17 (6 y to 17 y, mean 10.3 y) and 3 were 27, 42 and 51 year-old. Eight tumors were temporal, 1 frontal and 2 occipital. All patients have had pharmacoresistant epilepsy. Among all neuroepithelial tumors diagnosed in our Division in the last 22 years, DNT comprises 1.2% in patients under age 20 (n = 660), 0.24% in patients over 20 years (n = 1254), and 0.63% all ages considered (n = 1914).

Ganglioglioma and intractable epilepsy: clinical and neurophysiologic features and predictors of outcome after surgery

PURPOSE

To review the clinical, neurophysiologic, and radiological data of patients with ganglioglioma who had undergone evaluation and surgery in our Epilepsy Program.

METHODS

The medical and neurophysiologic records of 38 patients with intractable epilepsy and ganglioglioma were reviewed. Data underwent statistical analysis.

RESULTS

There were 28 temporal and 10 extratemporal resections, with a mean age at seizure onset of 10.5 years and mean age at surgery of 22 years. Five tumor resections performed earlier were recorded. Twenty-nine patients had auras and 20 had secondarily generalized seizures. All 28 patients with temporal tumor had complex partial seizures. Preoperative MRI demonstrated the tumor in 36 of 36 patients: 17 of 29 demonstrated gadolinium enhancement, and 17 of 36 had mass effect. Scalp interictal sharp waves were present in 32 patients, and in 15 they were multiregional. In two patients, scalp EEG seizure onset was from the hemisphere contralateral to the tumor. Postoperatively, 79% of patients (30 of 38) were seizure-free (Engel's class I) at 6 months, 72% at 1 year (26 of 36), and 63% at 2 years (20 of 32). Excellent outcome was associated with a lower age at operation (p = 0.008), shorter duration of epilepsy (p = <0.01), absence of generalized seizures (p = <0.01), and no epileptiform discharges on a postoperative EEG (p = 0.01).

CONCLUSIONS

Good surgical outcome is expected in patients with ganglioglioma despite years of medically resistant seizures. Good outcome may be achieved despite EEG findings that may conflict with tumor location, and is more likely when surgery is performed relatively soon after epilepsy onset.

Neuropathology of pediatric brain tumors

Pediatric central nervous system neoplasms include a spectrum of both glial and nonglial tumors that differ significantly in location and biological behavior from those of adults. Brain tumors in infants and children most often arise from central neuroepithelial tissue, whereas a significant number of adult tumors arise from central nervous system coverings (e.g., meningioma), adjacent tissue (e.g., pituitary adenoma), or metastases. Most adult brain tumors are supratentorial malignant gliomas, whereas the most common malignant pediatric brain tumor is the cerebellar primitive neuroectodermal tumor (medulloblastoma). This article reviews neuropathological characteristics of the more common pediatric brain tumors. Entities, such as the brainstem glioma, and less common neoplasms like the desmoplastic infantile ganglioglioma and the central nervous system atypical teratoid/rhabdoid tumor are reviewed because they occur almost exclusively in children. Known cytogenetic and molecular characteristics of childhood brain tumors are also reviewed.

[Dysembryoplastic neuroepithelial tumor. Case report]

Dysembryoplastic neuroepithelial tumor (DNT) is a relatively new neuroepithelial neoplasm that was first described by Daumas-Duport et al. in 1988. It was incorporated in the revised World Health Organization classification of brain tumors in 1993. The authors present the first case of DNT reported in the Latin-American literature. A 16-year-old woman had been found at age of five years to have complex partial seizures accompanied by secondary generalization. She was treated with various anti-epileptic drugs but always with incomplete control of seizures activity. Neurological examination was normal. Magnetic resonance imaging demonstrated a lesion in the left temporal lobe. She underwent a craniotomy with complete resection of the tumor. Histological study showed atypical neuroglial proliferation characteristic of DNT. Monoclonal antibody immunostaining for glial fibrillary acidic protein and S-100 protein confirmed the glial component, and neuronal specific enolase and synaptophysin emphasized the neuronal component.

Low-grade gliomas of chronic epilepsy: a distinct clinical and pathological entity

The authors present a summary of their recent experience regarding the management of patients with a variety of low-grade gliomas found during the evaluation for chronic epilepsy. These tumors are notable because the long-term patient outcome in this population is significantly better than the anticipated results of patients with the same tumors who do not have chronic epilepsy. Based on the long history of preoperative seizures (median 14 years), the frequent cortical location, and the absence of tumor recurrence or anaplastic transformation and the lack of mortality in this population, low-grade gliomas of chronic epilepsy appear to define a specific pathological entity that separates them from other histologically similar low-grade gliomas. Low-grade gliomas of chronic epilepsy also are notable for the absence of morphological features that characterize with dysembryoplastic neuroepithelial tumors (DNTs). Our evidence suggests that low-grade gliomas of chronic epilepsy should be recognized as a distinct pathological entity.

Dysembryoplastic neuroepithelial tumors located in the caudate nucleus area: report of four cases

OBJECTIVE AND IMPORTANCE

Dysembryoplastic neuroepithelial tumors (DNTs) histologically resemble gliomas but behave as stable lesions. These tumors initially were considered to be located exclusively within the supratentorial cortex. The four reported cases demonstrate that DNTs may also arise in the area of the caudate nuclei. Moreover, the peculiar topography of these lesions, which suggests a derivation from the subependymal plate, is in accordance with the putative origin of DNTs from secondary germinal layers.

CLINICAL PRESENTATION

The patients experienced partial seizures (two patients), generalized seizures (one patient), or headaches (one patient). All patients were young (17-26 yr) at the onset of symptoms, and all had normal results from their neurological examinations.

INTERVENTION

All lesions demonstrated a pseudocystic appearance on computed tomographic scans, were hypointense on T1-weighted magnetic resonance imaging scans, hyperintense on T2-weighted magnetic resonance imaging scans, and did not show contrast enhancement. The four tumors similarly lined the left or right caudate nuclei and expanded within the homolateral ventricle (three patients) or both lateral ventricles (one patient). In one patient, the tumor also involved the adjacent paraolfactory cortex.

CONCLUSION

In all patients, stereotactic biopsies helped to identify a specific glioneuronal element of DNTs. None of the tumors was operated on. Radiotherapy was performed in only one patient. A long pre- and/or postbiopsy imaging follow-up, which was available in two nontreated patients (3 yr and 16 yr), demonstrated the perfect stability of the lesion. The occurrence of DNTs in this peculiar location needs to be considered to avoid misidentification as "ordinary" gliomas and prevent useless aggressive treatment.

Dysembryoplastic neuroepithelial tumour: the Western Australian experience

Dysembryoplastic neuroepithelial tumour (DNET) is a rare tumour that is usually seen in the context of epilepsy surgery. The purpose of this study was to provide a profile of DNET in an unbiased population. The 2020 brain tumours diagnosed in Western Australia in the 10-year period 1982-1991 were reviewed; 5 cases of DNET were identified. All patients were neurologically intact and presented with complex partial seizures from a young age. Surgery was performed for tumour resection or biopsy in all cases; no patient underwent surgery specifically for epilepsy control. The lesions were intracortical, multinodular and were composed of astrocytes, oligodendrocytes and neurons. Three patients underwent total or subtotal resection and their seizures were either abolished or reduced in frequency. Two patients had biopsies only and were clinically unchanged. There has been no evidence of recurrence in up to 8 years' follow-up. The diagnosis of DNET is important because it is a surgically treatable benign tumour.

Hamartomas in the setting of chronic epilepsy: a clinicopathologic study of 13 cases

Hamartomas are a poorly defined group of lesions and a rare cause of chronic epilepsy. We studied 13 patients, nine males and four females, whose cause of seizures was attributed to a hamartoma. The patients ranged in age from 6 to 33 years (mean, 21 years). Seizure duration before surgery ranged from 1.5 to 22 years (mean, 10 years). Seven hamartomas were located on the right side and six on the left. Six were located in the frontal lobe, five in the temporal lobe, and two in the occipital lobe. Twelve patients underwent gross total resection of the lesion and one a partial resection. All consisted of a circumscribed, disorganized collection of glial cells, primarily astrocytes. Rarely a neuronal component was admixed. One lesion contained an increased number of small blood vessels. Eight (62%) hamartomas contained eosinophilic granular bodies, and focal microcalcification was observed in three lesions (23%). Adjacent cortical architectural abnormalities (cortical dysplasia) were identified in eight (62%) resection specimens. Necrosis, mitoses, and prominent cytological atypia were absent in all lesions. Differential diagnostic considerations include low grade astrocytoma, ganglioglioma, dysembryoplastic neuroepithelial tumor, and cortical dysplasia. Postoperatively, 10 patients (77%) had complete resolution or greater than 90% reduction of seizure frequency. Two patients (16%) developed recurrent seizures 8 and 13 months postoperatively. One patient who underwent a partial resection showed no decrease in seizure frequency. No lesion recurrence on imaging studies has been observed in the 12 patients who underwent gross total resection of their hamartoma during 1 to 51 months (mean, 14 months) follow-up. We conclude that hamartomas seen in the setting of chronic epilepsy are generally low-grade lesions that respond well to gross total resection. Circumscription and lack of significant cytological atypia help distinguish these lesions from other neoplastic causes of epilepsy. Hamartomas that arise in the setting of chronic epilepsy appear to be associated with increased incidence of cortical architectural abnormalities (cortical dysplasia) and represent maldevelopmental lesions.

Extraventricular neoplasms with neurocytoma features. A clinicopathological study of 11 cases

The clinicopathological features of a series of neuronal and mixed neuronal and astrocytic neoplasms of the CNS are described. Patients were aged 5 to 63 years. Six cases were composed predominantly of small round cells with clear cytoplasm resembling central neurocytoma but lacked the characteristic intraventricular location of that tumor. The remaining five cases had similar neurocytomatous features associated with a benign astrocytic component. Ganglion cells and hyalinization vessels were observed in both groups. The growth fraction evaluated with monoclonal antibody Ki67Mib1 was low, ranging from 1 to 1.5%. Immunohistochemical detection of synaptophysin played a crucial role in identifying the neuronal nature of these neoplasms and was instrumental in distinguishing them from oligodendrogliomas, with which they are readily confused. The neuronal nature of the oligodendroglial-like cells was confirmed ultrastructurally in one case. The present cases, together with others reported previously, suggest that neoplasms of the CNS with "neurocytic" components are more frequent than generally assumed and expand the morphologic spectrum of neuronal and mixed neuronal-glial tumors. Except for one patient who died postoperatively, all patients were alive at follow-up ranging from 6 to 80 months.

EEG features of focal malformations of cortical development

Recent advances in neuroimaging have allowed the detection and characterization of focal malformations of cortical developmental in a significant proportion of patients with epilepsy, many of whom were previously labelled as cryptogenic, allowing a better description of the associated electroencephalogram (EEG) features. Alpha activity is usually preserved, although superficial gyral abnormalities are often associated with overlying localized polymorphic delta activity, and occasionally abnormal fast activity. Most affected patients with epilepsy show interictal spikes. These are often broadly concordant with the structural abnormality but may show a wider anatomic distribution and be multifocal, or occasionally appear only in anatomically distant sites. In many patients the spikes are frequent and sometimes they occur continuously or in long trains. EEG findings are often stable over time, but some patients only show the development of slow wave changes or interictal spikes when followed serially for several years. A small proportion of patients with focal malformations of cortical development have EEG features mimicking idiopathic generalized epilepsy, and occasionally patients exhibit continuous generalized spike and slow wave activity in sleep. Electrocorticography studies confirm the often widespread nature of interictal spiking, but may also show highly epileptogenic patterns recorded directly from dysplastic cortex. The intrinsic epileptogenicity of areas of cortical developmental abnormalities has also been demonstrated by chronic intracranial studies and in vitro recordings of slices obtained from resected human dysplastic cortex. In this regard such developmental abnormalities are fundamentally different from acquired lesions such as tumors/vascular anomalies that usually exert their effects through changes in adjacent cortex.

The serotonergic innervation of the cerebral cortex in man and its changes in focal cortical dysplasia

We present the morphology and the laminar distribution of the serotonin (5-hydroxytryptamine, 5-HT) innervation of the cerebral cortex of patients who underwent cortical resection for partial seizures. The limits of the resections were established by stereoelectroencephalography. The 5-HT innervation was mapped by using an antiserum anti-5-HT. Two patients had cryptogenic epilepsies and two others had seizures related to focal cortical dysplasia. 5-HT immunoreactive axons were morphologically heterogeneous and projected diffusely to the cerebral cortex with regional-specific densities. Two types of terminal axon were demonstrated. Type I had large and spherical (intensely immunoreactive) varicosities and was distributed sparsely with a characteristic predominance in the molecular layer. Type II had fine and pleiomorphic varicosities (granular or fusiform) and was distributed through all cortical layers. The distribution of the 5-HT innervation varied according to the different architectonic areas investigated. The granular cortical areas characterized by a highly developed layer IV (primary somatosensory, primary visual and prefrontal cortices) had the highest density of 5-HT-ir fibers distributed from layer I to layer V. The agranular primary motor cortex had the lowest density with fibers preferentially seen in layers I, IIIa and V-VI. The orbital cortex with a poorly defined layer IV had an intermediate density with a laminar repartition predominant in the supragranular layers. In patients with cryptogenic epilepsies, the brain epileptogenic tissue was histologically normal as well as the serotonergic innervation. In contrast, in patients with focal cortical dysplasia, the dysplastic epileptogenic tissue was characterized by a serotonergic hyperinnervation. In agreement with previous data in primates, we give morphological evidence for two morphologically distinct serotonergic subsystems and for regional specific densities in the human cerebral cortex. Moreover, we previously reported an altered pattern of the catecholaminergic innervation in the same dysplasia areas. All these results provide evidence that this development epileptogenic lesion involves several sets of neurons which may contribute to epileptogenic activity.

Dysembryoplastic neuroepithelial tumor: a curable cause of seizures

Dysembryoplastic neuroepithelial tumor (DNT) was first characterized in 1988 by Daumas-Duport and Scheithauer [1], who described 39 cases in children with morphologically distinct brain tumors. Partial complex seizures (PCSs), well-defined neuroimages, and typical pathologic findings were characteristic. Surgical resection of the tumor was usually curative. We present a new case of a child with PCSs who was diagnosed and treated for DNT. The clinical presentation and the difficulties of the differential diagnosis are discussed.

Magnetic resonance imaging in epilepsy

The magnetic resonance imaging (MRI) appearance of the various histologic substrates of epilepsy and the clinical role of MRI in symptomatic epilepsy are reviewed. MRI is used clinically to identify potential surgical candidates among patients with epilepsy, assist in surgical planning, and help to determine the prognosis of patients with epileptic seizures. MRI can clearly characterize the morphologic substrates that underlie the electroclinical abnormalities noted in patients with epilepsy. The histologic substrates of symptomatic epilepsy can be divided into five major categories: tumors, disorders of neuronal migration and cortical organization, vascular malformations, mesial temporal sclerosis, and neocortical sclerosis attributable to brain injury (trauma, infection, inflammation, or infarction). Because of its ability to disclose subtle alterations in cortical architecture or changes in signal intensity, MRI is the most sensitive and specific imaging technique for the noninvasive identification of each of these substrates. Introduction of MRI into clinical practice during the past 10 years has substantially changed the management of patients with epilepsy.

Variations in the natural history and survival of patients with supratentorial low-grade astrocytomas

Data from 55 consecutive patients with low-grade astrocytomas treated between 1982 and 1990 were analyzed to determine specific outcome factors, including time to recurrence, incidence of anaplastic transformation, and survival. Gender, type of symptoms, contrast enhancement, and timing of radiation therapy were not significant in determining outcome. Patients who had symptoms for > 2 years and underwent gross-total resection of the tumor, with age as a continuous variable, were associated with significantly longer time to recurrence and survival. Within the population of patients with low-grade astrocytomas, patients with chronic epilepsy clearly had the best prognoses. There were no tumor recurrences or deaths in 27 patients with chronic epilepsy, regardless of the extent of surgery and without the use of radiotherapy. Ten-year survival was 100% for 31 patients who underwent gross-total tumor resection, regardless of the length of preoperative symptoms. Immediate postoperative radiotherapy did not prolong the time to recurrence, reduce the incidence of transition to more malignant tumors at recurrence, or increase the length of survival when compared with delayed radiotherapy. Because recurrence with a high-grade lesion caused 92% of the mortality in our series, the benefit in patients who underwent aggressive surgery seems to result from a significant decrease in the risk of recurrence when compared with patients who underwent anything less than gross-total resection. Our data also suggest that variability in the natural history of low-grade astrocytomas has a strong influence in determining survival and that tumors associated with chronic epilepsy are much less likely to become more malignant over time.

A case of dysembryoplastic neuroepithelial tumor of the parietal lobe with characteristic magnetic resonance imaging

The case of a 4 year old boy with a dysembryoplastic neuroepithelial tumor (DNT) of the left parietal lobe is reported. The DNT was located mainly in the cortex and showed no mass effect on magnetic resonance imaging (MRI). T1-weighted images of the DNT showed the characteristic findings of lesion hypointensity, but with a well preserved gyrus-like configuration. This lesion was isointense to the normal cortex on proton density imaging and hyperintense on T2-weighted imaging. The characteristic features on T1-weighted and proton density imaging in this patient were useful in differentiating DNT from other types of tumors. Histologic findings in DNTs, which include the presence of both glial and neuronal cells without atypia and no definite transitional zone between the adjacent disorganized cortical cell layers, suggest that DNT is not a true neoplasm but rather a dysplastic lesion. It is clinically important to differentiate this tumor both from other benign tumors and malignant tumors which have different prognoses and therapies. The distinctive MRI findings, as well as the histologic features of DNT, support the diagnosis in the clinical setting.

Multifocal neurocytoma/gangliocytoma with extensive leptomeningeal dissemination in the brain and spinal cord

This report describes an unusual neuronal tumor detected at the autopsy of a 17-year-old boy. The tumor showed multifocal parenchymal involvement with extensive leptomeningeal dissemination. The intraparenchymal lesions were small and located mainly in the subpial region of the cerebrum, cerebellum and spinal cord. Leptomeningeal dissemination was particularly pronounced at the base of the brain and around the spinal cord and presumably took place during the relatively long clinical course. The tumor was composed of small round cells and ganglion-cell-like cells. Only neuronal differentiation, as represented by immunostaining with antisynaptophysin antibody and the presence of dense-core vesicles in the cytoplasm, was evident in both types of cells. The small round cells appeared to exhibit the features of small, relatively mature neurons rather than those of neuroblasts. Moreover, our results suggested maturation from small round cells to ganglion-cell-like cells. The tumor appears to be related to gangliogliomas or dysembryoplastic neuroepithelial tumors, and we have chosen the term neurocytoma/gangliocytoma for the unusual lesion.