Extraventricular neurocytomas: pathologic features and clinical outcome

Atypical extraventricular neurocytoma in a 3-year-old girl: case report with radiological-pathological correlation

BACKGROUND

Extraventricular neurocytoma (EVN) is a rare neuronal tumor histologically similar to central neurocytoma but arising in the brain parenchyma outside the ventricles. The minority of EVNs show atypical features including increased proliferative index, microvascular proliferation, or necrosis, and are called atypical EVN. Most of atypical EVNs occur in adults, and the tumors in children are extremely rare. A radiological-pathological correlation and radiological clue to atypical EVNs have not been clarified.

CASE REPORT

We report a case of atypical EVN in a 3-year-old girl. Magnetic resonance imaging (MRI) revealed an extraventricular intraparenchymal tumor in the left frontal lobe, which was composed of homogeneous well-demarcated cystic component and peripheral ill-delineated solid component with enhancement. Angiography demonstrated vascular proliferation and arteriovenous shunting in the tumor. Histologically, the resected tumor was diagnosed as atypical EVN. Types of the tumor borders (well-circumscribed or infiltrative) and MRI findings correlated closely. Morphology of the tumor vasculature was remarkable for microvascular proliferation and dilated, thickened veins, which corresponded to the angiographic features.

CONCLUSION

Although rare, atypical EVN should be included in the differential diagnosis of a cystic mass in the cerebral hemispheres in children. Radiological evaluation of tumor borders and angiographic characteristics might be useful for predicting atypicality of the tumor.

Neurocytoma of the pituitary gland: A case report and literature review

Extraventricular neurocytomas (EVN) are rare central nervous system tumors, often located within the cerebral hemisphere. The present study reports a case of a 56-year-old male patient with bitemporal hemianopsia. Computed tomography and magnetic resonance imaging revealed a tumor in the sellar region. The tumor was totally excised. Postoperative histological examination of the tumor demonstrated that synaptophysin, chromogranin-A and neuron-specific enolase were positive, while luteinizing hormone, follicle-stimulating hormone, growth hormone, prolactin, adrenocorticotropic hormone, thyroid-stimulating hormone, glial fibrillary acidic protein, S-100, nestin and epithelial membrane antigen were negative, which were the main pathological features of neurocytomas. This is the fourth case of EVN located in the sellar region reported. The associated studies are also reviewed.

Estimation of proliferative potentiality of central neurocytoma: correlational analysis of minimum ADC and maximum SUV with MIB-1 labeling index

BACKGROUND

Central neurocytoma was initially believed to be benign tumor type, although atypical cases with more aggressive behavior have been reported. Preoperative estimation for proliferating activity of central neurocytoma is one of the most important considerations for determining tumor management.

PURPOSE

To investigate predictive values of image characteristics and quantitative measurements of minimum apparent diffusion coefficient (ADCmin) and maximum standardized uptake value (SUVmax) for proliferative activity of central neurocytoma measured by MIB-1 labeling index (LI).

MATERIAL AND METHODS

Twelve cases of central neurocytoma including one recurrence from January 2001 to December 2011 were included. Preoperative scans were conducted in 11, nine, and five patients for computed tomography (CT), diffusion-weighted imaging (DWI), and fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET), respectively, and ADCmin and SUVmax of the tumors were measured. Image characteristics were investigated using CT, T2-weighted (T2W) imaging and contrast-enhanced T1-weighted (T1W) imaging, and their differences were examined using the Fisher's exact test between cases with MIB-1 LI below and above 2%, which is recognized as typical and atypical central neurocytoma, respectively. Correlational analysis was conducted for ADCmin and SUVmax with MIB-1 LI. A P value <0.05 was considered significant.

RESULTS

Morphological appearances had large variety, and there was no significant correlation with MIB-1 LI except a tendency that strong enhancement was observed in central neurocytomas with higher MIB-1 LI (P = 0.061). High linearity with MIB-1 LI was observed in ADCmin and SUVmax (r = -0.91 and 0.74, respectively), but only ADCmin was statistically significant (P = 0.0006).

CONCLUSION

Central neurocytoma had a wide variety of image appearance, and assessment of proliferative potential was considered difficult only by morphological aspects. ADCmin was recognized as a potential marker for differentiation of atypical central neurocytomas from the typical ones.

Behavioral disorders as unusual presentation of pediatric extraventricular neurocytoma: report on two cases and review of the literature

BACKGROUND

Extraventricular neurocytomas (EVNs) are rare parenchymal brain tumors, distinct from central neurocytomas that are typically located within the supratentorial ventricular system. Seizures and headache represent the most common symptoms of extraventricular neurocytomas in the cerebral hemisphere both in adult and pediatric population.

CASE PRESENTATION

We describe two cases of pediatric EVN with clinical onset characterized by behavioral and attention deficit/ hyperactivity disorders. The association between behavioral/attention disorders in childhood and the presence of a frontal neurocytoma has never been described before. Furthermore, inappropriate levels of inattention, hyperactivity and impulsivity are common among the neurobehavioral and developmental disorders in childhood. We reviewed 43 pediatric cases of extraventricular neurocytoma included in the PubMed database and their clinical presentation, and we never found this unusual relationship.

CONCLUSION

In childhood, the attention/hyperactivity disorders seem to be often over-diagnosed. When these deficits are more subtle and do not well-fit in a specific neurocognitive disorder, the clinicians should have a suspicion that they might mask the clinical features of a frontal lesion. This paper is focused on the clinical presentation of the extraventricular neurocytoma and the possible organic etiology of an attention and hyperactivity deficit.

Central neurocytoma: establishment of the disease entity

The establishment and identification of central neurocytoma as a distinct disease entity are invaluable in catalyzing investigations of neuronal differentiation in central nervous system tumors. The discovery of neuronal differentiation in neuroepithelial tumors has been extended to extraventricular tumors and potentially to various glial tumors undergoing neuronal differentiation. Understanding the disease spectrum of neuronal and mixed neuronal-glial tumors is important for deciphering the mechanism of gliomagenesis.

A comparative study of intraventricular central neurocytomas and extraventricular neurocytomas

Similar histology and clinical behavior of both intraventricular central neurocytomas (CNs) and extraventricular neurocytomas (EVNs) may argue against the idea that EVNs were the distinct entity to distinguish from CNs in the 2007 World Health Organization classification. To explore respective characteristics and compare similarities and differences in CNs and EVNs, relevant clinical, radiological, operative and pathological data of 49 patients (35 CNs and 14 EVNs) in the Department of Neurosurgery at our hospital from 2005 to 2012 was reviewed and some comparisons between CNs and EVNs were conducted. The factors affecting posttreatment recurrence of CNs and EVNs were assessed by Cox regression analysis. In comparison, CNs showed a more typical clinical manifestation, and radiological and histopathological features, while EVNs demonstrated more malignant biological behavior, with higher MIB-1 index (p = 0.006), higher rate of atypia (p = 0.042), higher recurrence rate (p = 0.028), and shorter time to recurrence (p = 0.049). Subtotal resection was associated with higher rates of recurrence in both CNs (hazard ratio [HR] 6.16, p = 0.046) and EVNs (HR 5.26, p = 0.045), and atypia was also associated with a higher recurrence rate in CNs (HR 5.03, p = 0.042). CNs were thus easier to diagnose than EVNs, with typical clinical, radiological, and histopathological features, while the latter were more likely to show malignant biological behavior associated with atypia and recurrence. Total surgical resection is the optimal treatment choice for both CNs and EVNs, and patients with either CN or EVN with typical and/or totally resected lesions showed favorable clinical outcomes.

Primary central neurocytoma of the mesencephalic tectum in a pediatric patient

PURPOSE

Neurocytomas are tumors or neuronal differentiation, typically located within the supratentorial ventricular system. The extraventricular location is uncommon. A limited number of cases involving the brainstem have been reported and may be misdiagnosed as brainstem gliomas. Furthermore, midbrain neurocytomas are extremely rare, and no similar cases in pediatric patients have been reported in the literature to date. Brainstem location of neurocytomas often precludes gross total removal of the lesion, and in these cases, adjuvant therapies may be helpful.

METHODS

We report a case of a 16-year-old child who presented with signs and symptoms of increased intracranial pressure. The magnetic resonance imaging study demonstrated the presence of a primary mesencephalic tectum lesion causing obstructive hydrocephalus. The patient underwent emergent ventriculoperitoneal shunt implantation, resolving the hydrocephalus and the clinical symptoms. The lesion was partially removed through a suboccipital craniotomy and supracerebellar infratentorial approach to the mesencephalic tectum, without intraoperative complications.

RESULTS

Histological examination of the lesion was consistent with the diagnosis of extraventricular neurocytoma. The patient was referred to the oncology department for additional treatment with Gamma Knife radiosurgery.

CONCLUSIONS

Although brainstem neurocytoma is rare, this case demonstrates that it should be included in the differential diagnosis of brainstem gliomas. Because of brainstem tumor location, complete surgical removal may be challenging or not possible, with a high risk of postoperative neurological deficits. Adjuvant therapies may prevent local tumor growth in cases of tumor remnants or recurrences following microsurgery in selected cases.

Extraventricular neurocytoma, a comprehensive review

AIMS AND OBJECTIVE

Extra ventricular neurocytoms (EVN) are a rare parenchymal brain tumour distinct from central neurocytomas. This review attempts to analyze a series of seven cases of EVN from a single institute against the background of available literature.

METHOD

Retrospective analysis of the clinical manifestation, pathological features, imaging findings, microsurgical treatment effectiveness and progression free survival of seven cases of EVN operated between 2000-2012.

RESULTS

The study group included five females and two males in the age group 7-65 years (mean 30.71 yrs). The distribution of the lesion was as follows Lobar 4, Cerebellum 1, Pineal 1, spinal 1. The duration of clinical symptoms ranged from three months to seven years and the presentation was site and size specific. Cystic Changes (71 %), perilesional oedema (57 %) and heterogeneous contrast enhancement (85.7 %), and calcification (42 %) were a few distinct imaging characteristics. Increased perfusion correlated with atypical histology in two patients. Surgical resection remains the main management strategy for longer outcome and patients with STR + RT and GTR had comparable follow-up. Extremes of age and atypical histological features were adverse prognostic factors.

CONCLUSION

EVN are rare tumors with either glial or neuronal differentiation or a potential for atypical changes. Both, GTR and STR combined with RT, offer reasonably good outcome with overall comparable survival. The available literature of EVN is limited, larger series with long term follow-ups are needed to dictate the management protocol. The role of adjuvant therapy is still debatable and needs further validation.

Mixed neuronal-glial tumor in the temporal lobe of an infant: a case report

Background

Tumors that arise in the temporal lobes of infants and spread to the neural system are limited to several diagnoses. Herein, we present an infantile case of a temporal tumor showing neuronal and glial differentiation.

Case presentation

The patient was a 9-month-old boy with low body weight due to intrauterine growth retardation. At 9 months after birth, he presented partial seizures. Computed tomography scanning revealed a mass (35 * 40 mm) in the left temporal lobe. Isointensity was noted on magnetic resonance T1-weighted images and fluid attenuation inversion recovery images. The tumor was heterogeneously enhanced with gadolinium. Positron emission tomography showed high methionine uptake in the tumor. During surgery, the tumor, which was elastic and soft and bled easily, was gross totally resected. A moderately clear boundary was noted between the tumor and normal brain parenchyma. Histologically, the tumor mainly comprised a ganglioglioma-like portion and short spindle cells at different densities. The former was immunohistochemically positive for some kinds of neuronal markers including synaptophysin. The spindle cells were positive for glial fibrillary acidic protein, but desmoplasia was not observed.

Discussion

The tumor contained both neuronal and glial elements; the former were the main constituents of the tumor and included several ganglion-like cells. Because neuronal elements gradually transited to glial cells, a mixed neuronal-glial tumor was diagnosed.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2045126100982604

Extraventricular neurocytoma in pediatric populations: A case report and review of the literature

Extraventricular neurocytomas (EVNs) are rare neuronal tumors included in the definition of neoplasms in the 2007 World Health Organization classification of tumors of the central nervous system. Although a small case series of EVNs in adults has been previously reported, EVNs in pediatric populations are extremely rare. The current case report presents the clinicopathological features of an EVN in a 2-year-old female who presented with nausea and vomiting that had lasted for five days. In addition, an analysis of the imaging features, histology, treatment and prognosis of these reported rare lesions is presented. Immunohistochemically, EVNs are characterized by the robust expression of synaptophysin, but with a lack of oligodendrocyte transcription factor 2, isocitrate dehydrogenase enzyme isoform 1 (IDH1) R132/IDH2 R172 mutations and p53 immunoexpression. The treatment for EVNs in pediatric and adult populations is gross total resection, with post-operative radiation reserved for subtotal resection or recurrent disease. In addition, drop metastasis must be carefully avoided.

Atypical Central Neurocytoma with Recurrent Spinal Dissemination over a Period of 20 Years: A Case Report and Review of the Literature

We present an unusual case of a late recurrent central neurocytoma that was rediagnosed as an ependymoma and neurocytoma in accordance with changes in histological classifications. Case Description. A 56-year-old male teacher presented with incomplete transverse syndrome due to several intradural extramedullary tumors at the level of lumbar vertebrae 1-3. The histological diagnosis at the time was atypical ependymoma. One year later, two additional tumors were removed at the L5-S1 vertebral level. For 12 years, the patient remained tumor free on followup. Fourteen years after the initial diagnosis, the patient presented with thoracic paresthesias due to two new extramedullary tumors in the C7-T1 and the T8-T9 vertebral levels. After complete removal of the tumors, a radiological survey revealed an intracranial lesion in the third ventricle. Five months later, an additional lesion recurrence was removed surgically. The most recent histological diagnosis revealed an atypical central neurocytoma. In retrospect, the previous tumors were reclassified as neurocytoma according to the additional immunohistochemistry evidence. Discussion. There is no standard adjuvant treatment regimen for atypical neurocytoma; therefore, the patient is currently under close followup. Modern histopathological diagnosis is essential in these cases. Potential routes for dissemination of the tumor should be considered upon first recurrence.

5-aminolevulinic Acid fluorescence discriminates the histological grade of extraventricular neurocytoma

Extraventricular neurocytomas are rare brain tumors that have a diverse range of clinical characteristics. We describe two cases involving fluorescence-guided resection of extraventricular neurocytoma using 5-aminolevulinic acid (5-ALA) and evaluate the efficacy of the technique. We found that the tumor reactions to 5-ALA differed depending on the histologic grade. This finding shows that the 5-ALA fluorescence reaction may potentially be used as a biomarker of the clinical behavior of these tumors. To our knowledge, this is the first report in which fluorescence-guided resection was utilized for the resection of extraventricular neurocytomas.

Pathologic features and clinical outcome of central neurocytoma: analysis of 15 cases

OBJECTIVE

To get better recognition of central neurocytoma and diminish misdiagnosis.

METHODS

A retrospective review identified 15 cases of central neurocytoma. All cases of central neurocytoma were analyzed for their clinical symptoms, pathologic changes, immunohistochemical staining, prognosis and differential diagnosis. Clinical follow up was performed.

RESULTS

There were 8 males and 7 females aged 10-64 years (median 32.93 years). The most common presenting symptoms were those related to increased intracranial pressure (ICP), including headache (100%), papilledema (93%) and vomiting (80%). All tumors were located in the ventricular system. The tumors were composed of uniform cells with round nuclei and a fine chromatin pattern, and in some areas, small cells with perinuclear halo could be seen. In particular, the anuclear areas may have a fine fibrillary matrix (neuropil). Nuclear atypia and vascular proliferation appeared in two cases, respectively. Focal necrosis could be seen in one case. Immunohistochemical findings included expression of synaptophysin (15/15), neuron specific enolase (12/15) and glial fibrillary acidic protein (GFAP) (3/15). MIB-1 proliferation index ranged from 0.8-12.5%, and was more than 2% in 3 of 15 cases assessed. Follow-up information of 11 patients was available.

CONCLUSIONS

Central neurocytoma has a favorable prognosis in general, but in some cases, the clinical course could be aggressive. Increase of GFAP positivity, proliferation index and vascular proliferation might suggest a more malignant process.

Computed tomography and magnetic resonance features of extraventricular neurocytoma: a study of eight cases

AIM

To present the neuroradiological and clinical findings of extraventricular (central) neurocytomas (EVNs) to increase awareness of this entity.

MATERIALS AND METHODS

The computed tomography (CT; n = 6), magnetic resonance imaging (MRI; n = 8), and clinical presentations of eight patients with pathologically documented EVN were retrospectively analysed.

RESULTS

Most tumours were well circumscribed and occurred in young adults. Six tumours were solid or solid-cystic, five of these showed contrast enhancement and three contained calcifications. Multiple small cysts were present in one solid mass and had a "soap bubble" or spongy appearance on MRI. Two other tumours were predominantly cystic; these demonstrated slight contrast enhancement, which contained calcifications. Of the six cases assessed using CT, three showed predominantly hyperdensity and three showed hypodensity, with a mean attenuation value of 75 HU. At MRI, eight masses were isointense (n = 4) or hypointense (n = 4) to grey matter on T1-weighted images and hyperintense (n = 6), isointense (n = 1), or hypointense (n = 1) on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. Signal voids were visible in two cases. Four tumours had mild or moderate peritumoural oedema.

CONCLUSION

EVN is a rare neoplasm that can have significant overlap in imaging appearance with other primary brain neoplasms; therefore, it is difficult to make an accurate preoperative diagnosis. However, EVN should be considered in the differential diagnosis when a large cerebral parenchymal mass with cystic change and calcification is encountered in younger patients.

Extraventricular neurocytoma of the sellar region with spinal dissemination

Extraventricular neurocytoma (EVN) is a rare tumor that mainly occurs in the cerebral hemispheres and spinal cord. Sellar neurocytoma is extremely rare, with only two previously reported cases. We report a sellar EVN in a 48-year-old man presenting with visual impairment. This tumor was partially resected. The residual tumor disappeared on MRI with adjuvant radiotherapy. However, 2 years later the tumor recurred with craniospinal dissemination, which is also very rare, with only four previously reported cases. The recurrent tumor showed atypical features with an MIB-1 LI score of 3 %. It is suggested that postoperative adjuvant radiation therapy with long-term follow-up is required for incompletely resected EVN.

Frontal transcortical approach in 12 central neurocytomas

BACKGROUND

Central neurocytomas (CN) are rare intraventricular tumors with benign clinical behavior that typically affect young adults. Although a favorable prognosis is generally expected after adequate management, there is no general consensus on the standard of therapy. We evaluated the efficacy and safety of radical surgery for the management of CN.

METHODS

Between 1996 and 2010, 12 patients with CN (eight males and four females; range, 18 to 62 years; mean age, 28.5 years) were surgically treated in our institution. The initial goal of therapy was complete resection through a frontal transcortical approach, and repeat surgery was done in cases of residual or recurrent disease. The mean follow-up period was 51.2 months (range, 14-149 months).

RESULTS

Complete resection was achieved in all patients either with primary (nine patients, 75 %) or second-look surgery (three patients, 25 %). No mortalities occurred and there were four surgery-related complications (two events of transient hemiparesis, one transient aphasia, and onepostoperative subdural hygroma). All patients were alive with normal activities of daily living at the last follow-up. Two patients (16.6 %) experienced a single recurrence at 26 and 66 months, one of whom underwent redo-surgery.

CONCLUSION

For the management of CN, complete resection is feasible, effective, and safe. Repeat surgery may be a viable option in cases of residual or recurrent disease and the use of radiotherapy can be avoided in this young population.

Surgical management of intraventricular central neurocytoma: 92 cases

OBJECTIVE

To analyse the clinical characteristics of intraventricular central neurocytomas and gain a better understanding of the surgical management and treatment strategies.

METHODS

A total of 92 cases of intraventricular central neurocytomas with initial treatment using surgical resection were studied retrospectively.

RESULTS

Among 48 male and 44 female patients, 65 underwent gross total resection and 27 underwent subtotal resection. Transcortical or transcallosal approaches were performed, and there was no significant difference between the two approaches in terms of effects and complications. Tumours with calcification or adhesion had a significant lower gross total resection rate. Three patients died after surgery. During follow-up, 55 patients underwent postoperative radiotherapy and four patients had a recurrence of the tumour.

CONCLUSION

Central neurocytomas mostly occur in the lateral ventricle system near the foramen of Monro. Therefore, total resection is the best treatment. Two surgical approaches are possible as treatment. Calcifications or adhesions affect the gross total resection of the tumour. Radiation therapy or radiosurgery therapy can be chosen as a salvage treatment in case of recurrence.

MR imaging findings of extraventricular neurocytoma: a series of ten patients confirmed by immunohistochemistry of IDH1 gene mutation

BACKGROUND

Extraventricular neurocytomas (EVNs) are rare neuronal tumors included as neoplasms in the 2007 World Health Organization (WHO) classification of tumors of the CNS. Although a few case reports describing EVNs have been published, a systematic analysis of MR imaging findings of EVN has not been reported. Furthermore, imaging findings of IDH1 mutation-negative EVNs have not yet been reported. The aim of our study is to describe the MR imaging findings of IDH1 mutation-negative EVNs.

METHODS

MR images of ten patients with pathologically confirmed IDH1 mutation-negative EVNs were retrospectively reviewed. Conventional MR imaging of ten EVNs were reviewed with emphasis on the location, signal intensities, patterns, and grades of enhancement as well as the presence/grade of peritumoral edema, intratumoral cyst, hemorrhage, and calcification. The study also reviewed the results of DWI (b = 1,000 s/mm(2), n = 7).

RESULTS

Seven EVN cases were located in the cerebral hemisphere, and the remaining cases were in the cerebellum and thalamus. Of those in the cerebral hemisphere, five were cortically based tumors. The tumors showed no or mild peritumoral edema. Eight tumors were enhanced on the postcontrast T1WIs. An intratumoral cyst, hemorrhage, and calcification were detected in four, one, and two cases, respectively. On DWI, only one case showed a lower ADC value than the brain parenchyma.

CONCLUSION

EVNs are usually cortically based infiltrative hemispheric tumors with contrast enhancement, higher ADC value, and sometimes small cystic component, but hardly show peritumoral edema or intratumoral hemorrhage. The differential diagnosis of these findings includes low-grade glioneuronal tumors and low-grade gliomas.

Infiltrative brainstem and cerebellar neurocytoma

Neurocytomas are typically intraventricular in location, and extraventricular neurocytomas are uncommon. The authors report the unique case of a 15-year-old girl who was found to have a low-grade neurocytoma infiltrating the brainstem and cerebellum and spreading along the CSF pathways to the lateral and third ventricles. The patient underwent endoscopic third ventriculostomy to treat associated hydrocephalus, and biopsy specimens from intraventricular tumor nodules were obtained. Because of the low-grade pathology, the fact that the lesion was not amenable to resection, and the extensive radiation field required for radiation therapy, she has been treated conservatively with close follow-up. Over the course of almost 4 years since diagnosis, no additional treatment has been required. Neurocytoma with widespread infiltration of the brainstem and cerebellum has not been previously reported.

Clear cell tumors of the central nervous system: a case-based review

Clear cell tumors of the central nervous system (CNS) encompass a variety of tumor subtypes that are challenging to diagnose given their similar morphologic features. Here, I use a case-based approach to review the clinicopathologic and radiologic features to help guide the general pathologist in the diagnosis of clear cell tumors of the CNS. First, the reader is invited to study 6 images of different CNS tumors with clear cell morphology. Then, each case is expanded in light of clinical and radiologic data and includes a histopathologic description of the tumor. A brief discussion follows with up-to-date diagnostic tools. Finally, I propose an immunohistochemical algorithm to navigate through the complex features that characterize clear cell tumors of the CNS. This review aims to provide a comprehensive approach to diagnosing clear cell neoplasms of the CNS based on improved assessment of the clinicopathologic and radiologic features of each entity.

MR imaging of cerebral extraventricular neurocytoma: a report of 9 cases

Extraventricular neurocytoma is a rare entity, most frequently occurring in brain parenchyma outside the ventricular system. The purpose of this study was to characterize the MR imaging findings in a series of 9 patients with EVN verified by results of pathologic examination. All 9 EVNs were solitary and intracranially located. Eight lesions were well demarcated, and 3 showed intratumoral hemorrhage. The solid parts of 7 tumors were primarily isointense on T1-weighted images and heterogeneously enhanced on T1WI with contrast. Although cerebral EVNs can present a wide spectrum of appearances on MR, the imaging patterns appear to vary according to anatomic location and cellularity. Lesions in frontal or parietal lobes often present as well-demarcated large masses with cystic degeneration, hemorrhage, mild-to-moderate edema, and inhomogeneous enhancement. Moreover, the general isointensity of the solid parts of EVN on T1WI may be of some specificity.

Hemispheric extra-ventricular glioneurocytoma: a clinicopathological review with detailed immunohistochemical profile

Glioneuronal tumors have recently been recognized in the WHO Classification of Tumors of the Central Nervous System, 2007 [14]. However, the entities included in this category do not encompass all the glioneuronal tumors encountered during practice. We characterize a new entity called glioneurocytoma (GNC) showing distinct morphology with glial and neuronal differentiation. We reviewed 10 cases of glioneurocytomas diagnosed in our department during 2003 and 2004, with emphasis on clinicopathological features, immunohistochemical profile, genetic aberrations and prognosis. The cases included in the study showed equal gender distribution and age range of 23-40 years and mean age of 34.4 years at the time of initial presentation. Most of the tumors were centered in the frontal lobe. In our study, GFAP was the most sensitive and relatively specific marker for glial differentiation and remains the marker of choice for glial differentiation. CD56 and S100 protein were sensitive but non-specific. Vimentin, CD57 and NF were non-contributory in the immunohistochemical work up of glioneurocytomas. We concluded that the diagnosis of glioneurocytomas requires attention to morphological details and proper immunohistochemical assessment, using a panel of both glial and neuronal markers. Particular attention is recommended to the existence of the intermediate neurocytic cells which may be unique for these tumors. Future implication with full molecular analysis for gene expression profiling is suggested for proper and accurate identifying this entity.

Pontine extraventricular neurocytoma in a child

Extraventricular neurocytomas mimic central neurocytomas histologically but are located outside the lateral and/or third ventricles. Pontine neurocytomas represent an extremely rare subset of extraventricular neurocytomas, and reports are limited to 2 adults followed under 28 months. The authors present the case of a 14-year-old boy who initially underwent near-total resection of a pontine extraventricular neurocytoma. One-year postoperative surveillance imaging revealed a small, local recurrence treated with intensity-modulated radiation therapy. This case details the diagnosis and management of the first reported pontine extraventricular neurocytoma in a child with 4.5-year follow-up data.

Dural metastasis of atypical extraventricular neurocytoma with the codeletion of chromosomes 1p/19q

Extraventricular neurocytoma (EVN) is a rare neoplasm described in the 2007 World Health Organization classification of tumours of the nervous system. Due to the rarity of the tumour, there is limited literature available. The clinical characteristics, pathological features, biological behaviour and outcome of EVN remain unclear, and there are challenges regarding its diagnosis and management. The present case was a 75-year-old man who had been experiencing slow responses to stimuli for 1 month prior to hospital admission. A diagnosis of atypical EVN was made on the basis of pathology and immunohistochemistry results. Atypical pathological features included vascular proliferation, the presence of mitosis and a high MIB-1 (an antibody against Ki-67) labelling index. The disease recurred 7 months after the initial complete resection and radiation treatment, presenting with dural metastasis and codeletion of chromosomes 1p/19q. The present case history and treatment course are discussed with respect to the literature.

Atypia predicting prognosis for intracranial extraventricular neurocytomas

OBJECT

The literature, at present, provides limited information about extraventricular neurocytomas (EVNs) and is almost exclusively composed of case reports or small case series. Treatment for EVNs has largely been guided by results from central neurocytoma outcome studies. The authors present an analysis of all reported intracranial EVN cases to establish if tumor histopathological features can substratify EVN into groups with differing prognosis and help guide treatment decisions.

METHODS

The authors identified studies reporting histology, treatment modality, and outcomes for patients with intracranial EVN. The rates of recurrence and survival for patients were compared using Kaplan-Meier analysis. Atypical tumors, defined by MIB-1 labeling index exceeding 3% or atypical histological features, were compared with typical tumors, and patients 50 years of age or older were compared with those younger than 50 years of age.

RESULTS

Eighty-five patients met the inclusion criteria, and 27% of them had an atypical histology. Typical EVNs had a better prognosis than atypical EVNs after primary treatment, with a 5-year recurrence rate of 36% compared with 68% (p < 0.001), and a 5-year mortality rate of 4% compared with 44%, respectively (p < 0.001). Age younger 50 years was associated with a better prognosis than age equal to or greater than 50 years, with a 5-year recurrence rate of 33% and 74%, respectively (p < 0.001), and a 5-year mortality rate of 4% and 52%, respectively (p < 0.001). Multivariate analysis demonstrated that atypical EVNs carried significantly increased risk for recurrence (hazard ratio [HR] 4.91, p < 0.001) and death (HR 22.91, p < 0.01). Gross-total resection was superior to subtotal resection (STR) alone in tumor control rates for typical EVNs (95% and 68%, p < 0.05), and there was a trend for adjuvant external-beam radiotherapy to benefit STR. There was suggestion of similar trends in patients with atypical EVNs.

CONCLUSIONS

There are at least 2 distinct histological subtypes of EVN, with different prognostic significances. Atypia or MIB-1 labeling index greater than 3% is a significant predictor of poor prognosis for EVNs. Complete resection or more aggressive attempts at providing adjuvant therapy following STR appear to improve the prognosis for patients with EVNs. Although the authors' results are informative, there are limitations to their analysis. Given the relatively modest total number of cases reported, as well as the nature of the disaggregated analysis, the authors were not able to use formal meta-analytical methods to limit the impact of between center heterogeneity. Additionally, they were not able to control for individual differences in data analysis and presentation across the different studies included in their analysis.

Atypical extraventricular neurocytoma

The authors report a case of atypical extraventricular neurocytoma (EVN) transformed from EVN which had been initially diagnosed as an oligodendroglioma 15 years ago. An 8-year-old boy underwent a surgical resection for a right frontal mass which was initially diagnosed as oligodendroglioma. When the tumor recurred 15 years later, a secondary operation was performed, followed by salvage gamma knife treatment. The recurrent tumor was diagnosed as an atypical EVN. The initial specimen was reviewed and immunohistochemistry revealed a strong positivity for synaptophysin. The diagnosis of the initial tumor was revised as an EVN. The patient maintained a stable disease state for 15 years after the first operation, and was followed up for one year without any complications or disease progression after the second operation. We diagnosed an atypical extraventricular neurocytoma transformed from EVN which had been initially diagnosed as an oligodendroglioma 15 years earlier. We emphasize that EVN should be included in the differential diagnosis of oligodendroglioma.

Vascular patterns of brain tumors

Multiple vascular patterns are presented in tumors of the central nervous system (CNS), including microvascular hyperplasia, branching capillaries, numerous capillaries without definite pattern, hyalinized vessels, and angiomatous area. These vascular patterns play important roles in pathological diagnosis of brain tumors. Because of insufficient recognition of the significance of the various vascular patterns, only a few of them have been applied in pathological diagnosis, leading to missed diagnosis and diagnostic errors. Microvascular hyperplasia can present in multiple brain tumors but display different diagnostic values. Otherwise, varied brain tumors characterized by branching capillaries or vascular pattern mimicking branching capillaries should be given careful consideration. Therefore, a familiarity of these tumors and their vascular pattern is essential for general pathologists. This study reviews the value of various kinds of vascular patterns for pathological diagnosis of brain tumors, constructs a framework for better understanding, and provides a novel perspective for general pathologists.

Youngest case of third ventricular anaplastic neurocytoma

A 6-year-old child presented to us with on and off headache and vomiting for 4 months. On examination, there was bilateral papilledema with mild intracranial hypertension but with no neurological deficits. Magnetic resonance imaging (MRI) showed third ventricular mass with obstructive hydrocephalus with possibility of glioma. The patient underwent gross tumor excision and histopathology confirmed anaplastic neurocytoma. The postoperative MRI showed residual disease. The patient treated with adjuvant radiotherapy and temozolamide chemotherapy.

Gamma knife radiosurgery for cranial neurocytomas

Gamma-knife surgery may be an effective alternative for treatment of central neurocytomas owing to its relative safety compared with conventional radiotherapy. In this paper we present results of gamma-knife treatment (GKS) of residual or recurrent neurocytomas. Twenty-two patients (14 female, 8 male) with recurrent or residual neurocytomas who underwent GKS were included. Diagnosis was based on histological findings. The proliferative potential of the tumors was examined by immunostaining with MIB-1 antibody, which is specific for detection of Ki-67 antigen. Tumor volume was determined by using post-gadolinium magnetic resonance images. After GKS treatment, MR imaging was scheduled at three-month intervals in the first year, at six months intervals in the second year, and yearly thereafter. Histopathological diagnoses were: 18 cases of central neurocytomas, two liponeurocytomas, one cerebral neurocytoma and one cerebellar neurocytoma. The MIB1 labeling index (LI) varied from 0 to 5.7%. Marked reduction in tumor volume was seen in 15 patients. In six patients, the tumor volume remained unchanged, and progression was observed for one patient. No complications because of GKS were noted. Shrinking effect on tumor volume increased with increasing duration of follow-up. On the other hand, high MIB labeling index did not seem to have an effect on tumor response to GKS treatment. Findings of this study suggest that GKS is an effective and safe treatment alternative for residual or recurrent neurocytomas. However, its effectiveness should be confirmed with larger studies.

Neurocytoma of the cerebellum

Background:

Neurocytomas are benign central nervous system tumor composed of small cells with characteristics of neuronal differentiation; they are usually located in the supratentorial periventricular region, in close relation to the septum pellucidum and the foramen of Monro.

Case Description:

Herein we report a rare case of a neurocytoma located in the cerebellar hemisphere. To date there are only four such reported cases.

Conclusion:

Neurocytomas should be considered in the differential diagnosis of mass lesions in the cerebellum.

Olig2 is useful in the differential diagnosis of oligodendrogliomas and extraventricular neurocytomas

A 42-year-old woman had suffered from headaches since April 2009. Computed tomography revealed a tumor with marked calcification in the left frontal lobe adjacent to the left anterior horn of the lateral ventricle. T1-weighted gadolinium-enhanced magnetic resonance imaging showed a well-enhanced tumor at the lesion. Dynamic methionine positron emission tomography showed no delayed methionine attenuation. Initial preoperative diagnosis was extraventricular neurocytoma (EVN). However, oligodendroglioma was determined upon a second diagnosis. The patient underwent total tumor removal. Hematoxylin and eosin staining showed the characteristic fried egg-like cells, round nuclei, and immunohistochemically, the tumor cells were positive for glial fibrillary acidic protein, synaptophysin, neuronal nuclear antigen, microtubule-associated protein 2 and Olig2. The MIB-1 labeling index was 20%, which suggested malignancy. Although these findings demonstrated that the tumor had glioneuronal character, it was difficult to differentiate between EVN and oligodendroglioma. There have been reports that Olig2 immunohistochemistry is generally positive in cases of oligodendroglioma, but not in cases of neurocytoma. We completed the diagnosis as oligodendroglioma. Subsequent electron microscopy results presented oligodendroglial but not neuronal characteristics. We concluded that Olig2 is useful in the differential diagnosis of oligodendrogliomas and EVNs.

Extraventricular neurocytomas

Central neurocytomas are uncommon, benign tumours of the central nervous system. These tumours have been recognised outside the limits of the cerebral ventricles and, in these instances, have been called as 'extraventricular neurocytomas'. The authors described a case of frontal neurocytoma and discuss the current knowledge on these infrequent neoplasms.

Oligodendroglial tumors: diagnostic and molecular pathology

Oligodendroglial tumors, which encompass pure oligodendroglioma and mixed oligoastrocytoma, represent the second most common glioma in adults after glioblastoma. They remain controversial neoplasms in the realm of surgical neuropathology. The early recognition of their more favorable prognosis and responsiveness to treatment when compared with diffusely infiltrating astrocytomas has influenced the pathologic diagnostic interpretation, and resulted in a pervasive interobserver variability. The more recent finding of an increased frequency of 1p/19q deletion in these tumors by cytogenetic analysis, and the association of this molecular abnormality with a better prognosis has greatly impacted the field of neuro-oncology. In this review, we focus on important histopathologic aspects in the evaluation of oligodendroglial tumors, key differential diagnoses, and highlight particular clinical and molecular characteristics, as well as current diagnostic and conceptual controversies.

Seizures in patients with low-grade gliomas--incidence, pathogenesis, surgical management, and pharmacotherapy

Seizures complicate the clinical course of > 80% of patients with low-grade gliomas. Patients with some tumor variants almost always have epilepsy. Diffuse low-grade gliomas (LGG) are believed to cause epilepsy through partial deafferentiation of nearby brain cortex (denervation hypersensitivity). Glioneural tumors may interfere with local neurotransmitter levels and are sometimes associated with structural abnormalities of the brain which may produce seizures. The severity of tumor associated epilepsy varies considerably between patients. Some cases may present with a first seizure. Others suffer from long-standing pharmacoresistant epilepsy. Seizure control rates of > 70-80% can be expected after complete tumor resections. Patients with drug-resistant epilepsy require a comprehensive preoperative epileptological work-up which may include the placement of subdural (and intraparenchymal) electrodes or intraoperative electrocorticography (ECoG) for the delineation of extratumoral seizure foci. Partial and subtotal tumor resections are helpful in selected cases, i.e. for gliomas involving the insula. In one series, 40% of patients presented for surgery with uncontrolled seizures, i.e. medical therapy alone often fails to control tumor-related epilepsy. Use of the newer (second generation) non-enzyme inducing antiepileptic drugs (non-EIAED) is encouraged since they seem to have lesser interactions with other medications (e.g. chemotherapy). Chemotherapy and irradiation may have some minor beneficial effects on the patients' seizure disorder. Overall 60-70% of patients may experience recurrent epilepsy during long-term follow-up. Recurrent seizures (not infrequently heralding tumor recurrence) after surgery continue to pose significant clinical problems.

Central neurocytoma in third and fourth ventricles with aqueductal involvement

Central neurocytomas are characterized by their intraventricular locations, usually arising from the lateral ventricles and their benign clinical course. Variations in location, histology and clinical behaviour have been reported in recent years. The authors present two cases of central neurocytomas arising in the third and fourth ventricles with aqueductal involvement. The atypical features in their location and behaviour are discussed. The cases represent the extended spectrum of central neurocytomas.

Neurocytoma of the spinal cord: report of three cases and review of the literature

The spinal cord is a very rare location for extra-ventricular neurocytomas. Composed of small round cells with neuronal differentiation, neurocytoma has a particularly favourable prognosis. Long disease-free intervals have been observed in patients who received sub-total removal and radiotherapy. A careful intra-operative frozen section examination is helpful in avoiding excessive surgical tissue disturbance and to identify the best treatment option. To date, eight cases of neurocytoma of the spinal cord have been described. We report three more patients; one with very long survival, and review the published literature for this condition.

Extraventricular neurocytoma in a child: case report and review of the literature

Neurocytomas are relatively rare central nervous system tumors first described in intraventricular sites but increasingly recognized in the brain and spinal cord parenchyma. Herewith, we report a case of a 3-year-old girl with generalized seizures. Computed tomography and magnetic resonance imaging revealed a lesion in the left frontal lobe. Angiography showed minimal vascularity. The tumor was totally excised. Histopathologic examination demonstrated an extraventricular neurocytoma. On follow-up magnetic resonance imaging after 1 year, no evidence of tumor recurrence was noted. Cerebral neurocytomas are histologically low-grade tumors and radical surgery is curative; they should be included in the differential diagnosis of cerebral tumors in children.