Comparative analysis of NeuN immunoreactivity in primary brain tumours: conclusions for rational use in diagnostic histopathology

Doublecortin immunolabeling in canine gliomas with distinct degrees of tumor infiltration

Increased doublecortin (DCX) immunolabeling at the tumor margins has been associated with tumor infiltration in human glioma and canine anaplastic meningioma. No association between DCX immunolabeling and glioma infiltration has been reported in dogs, to our knowledge. Here we compare the DCX immunolabeling in 14 diffusely infiltrating gliomas (gliomatosis cerebri) and 14 nodular gliomas with distinct degrees of tumor infiltration. Cytoplasmic DCX immunolabeling was classified according to intensity (weak, moderate, strong), distribution (1 = <30% immunolabeling, 2 = 30-70% immunolabeling, 3 = >70% immunolabeling), and location within the neoplasm (random or at tumor margins). Immunolabeling was detected in 6 of 14 (43%) diffusely infiltrating gliomas and 8 of 14 (57%) nodular gliomas. Diffusely infiltrating gliomas had moderate and random immunolabeling, with distribution scores of 1 (4 cases) or 2 (2 cases). Nodular gliomas had strong (6 cases) or moderate (2 cases) immunolabeling, with distribution scores of 1 (3 cases), 2 (3 cases), and 3 (2 cases), and random (6 cases) and/or marginal (3 cases) immunolabeling. Increased DCX immunolabeling within neoplastic cells palisading around necrosis occurred in 4 nodular gliomas. DCX immunolabeling was not increased at the margins of diffusely infiltrating gliomas, indicating that DCX should not be used as an immunomarker for glioma infiltration in dogs.

Benign Spinal Tumors

Benign spinal intradural tumors are relatively rare and include intramedullary tumors with a favorable histology such as low-grade astrocytomas and ependymomas, as well as intradural extramedullary tumors such as meningiomas and schwannomas. The effect on the neural tissue is usually a combination of mass effect and neuronal involvement in cases of infiltrative tumors. The new understanding of molecular profiling of different tumors allowed us to better define central nervous system tumors and tailor treatment accordingly. The mainstay of management of many intradural spinal tumors is maximal safe surgical resection. This goal is more achievable with intradural extramedullary tumors; yet, with a meticulous surgical approach, many of the intramedullary tumors are amenable for safe gross-total or near-total resection. The nature of these tumors is benign; hence, a different way to measure outcome success is pursued and usually depends on functional rather than oncological or survival outcomes.

Doublecortin immunolabeling and lack of neuronal nuclear protein immunolabeling in feline gliomas

Doublecortin (DCX) and neuronal nuclear protein (NeuN) can be used as immunomarkers of neuronal progenitor cells and mature neurons, respectively. Increased DCX immunolabeling has been associated with tumor invasion in human gliomas and anaplastic canine meningiomas. These immunomarkers have not been assessed in feline gliomas. Here we characterized the DCX and NeuN immunohistochemistry (IHC) profile in 11 feline gliomas (7 oligodendrogliomas, 4 astrocytomas). Immunolabeling was classified according to intensity (weak, moderate, strong), distribution of neoplastic cell immunolabeling (1 = <30%, 2 = 30-70%, 3 = >70%), and predominant location within the neoplasm (random or at tumor margins). DCX immunolabeling was strong in 6 cases, weak in 4 cases, and moderate in 1 case. The distribution of DCX immunolabeling was characterized as 1 (4 cases), 2 (4 cases), and 3 (3 cases). DCX immunolabeling occurred predominantly in astrocytomas, which had stronger immunostaining at the tumor margins. NeuN immunolabeling was absent in all cases. Our IHC findings are similar to those reported for DCX and NeuN IHC in canine gliomas. The increased DCX immunolabeling at tumor margins is similar to labeling in invasive human gliomas and anaplastic canine meningiomas.

Failure to Thrive Revealing a Pilomyxoid Astrocytoma: An Uncommon Case Report with Literature Review

Pilomyxoid astrocytoma (PMA) is a freshly described figure of low-grade neoplasms encountered in early childhood. Nevertheless, its precise classification by the World Health Organization (WHO) is still debatable. Making an exact diagnosis relies on histological and immunohistochemical pathognomonic features with specific radiological findings. PMA behaves aggressively with a shorter progression-free survival, and its management is unfortunately still arguable. We describe a rare case of PMA involving the suprasellar region who displays symptoms consistent with diencephalic syndrome. The diagnosis was made by magnetic resonance imaging (MRI) focused on the hypothalamic-pituitary axis, and the patient underwent a subtotal tumor resection combined with chemotherapy. Diagnosis of brain tumors should be kept in mind in young children with generalized and severe unexplained loss of subcutaneous fat with failure to thrive after ruling out classical causes.

A Rare Case of a Congenital Nasopharyngeal Ganglioglioma With Dyspnea in a 1-Month-Old Male Infant: A Case Report

Background: A ganglioglioma (GG), a tumor with both neuronal and astrocytic components, rarely occurs outside the central nervous system. Case Summary: We present the first reported case of a 1-month-old male with a congenital nasopharyngeal GG, nasal congestion, and dyspnea; we include the operative video. Magnetic resonance imaging was used to explore whether the tumor communicated with the intracranial space. We used an endoscopic plasma technique to ensure complete tumor resection. This afforded a good visual field, endoscopic magnification, and good hemostasis. Conclusions: We report a rare case of a nasopharyngeal GG triggering nasal congestion and dyspnea in a 1-month-old male, and report our experience with the treatment of nasopharyngeal GG and similar diseases.

Low Expression of miR-466f-3p Sustains Epithelial to Mesenchymal Transition in Sonic Hedgehog Medulloblastoma Stem Cells Through Vegfa-Nrp2 Signaling Pathway

High-throughput analysis has improved the knowledge of medulloblastoma (MB), the leading cause of cancer related death in children, allowing a better comprehension of the key molecular pathways in MB pathogenesis. However, despite these advances, 30% of patients still die from the disease and survivors face severe long-term side effects. Cancer stem cells (CSCs) represent a subset of cells that not only drive tumorigenesis, but are also one of the main determinants of chemoresistance. Epithelial mesenchymal transition (EMT) is a hallmark of cancer and up to now few data is available in MB. To give insight into the role of the EMT process in maintaining the mesenchymal phenotype of CSCs, we analyzed the expression of EMT related transcripts and microRNAs in these cells. We firstly isolated CSCs from Sonic Hedgehog (SHH) MB derived from Ptch1 heterozygous mice and compared their expression level of EMT-related transcripts and microRNAs with cerebellar NSCs. We identified two molecules linked to SHH and EMT, Vegfa and its receptor Nrp2, over-expressed in SHH MB CSCs. Inhibition of Vegfa showed impairment of cell proliferation and self-renewal ability of CSCs concurrent with an increase of the expression of the EMT gene, E-cadherin, and a decrease of the EMT marker, Vimentin. Moreover, among deregulated microRNAs, we identified miR-466f-3p, a validated inhibitor of both Vegfa and Nrp2. These results allowed us to describe a new EMT molecular network, involving the down-regulation of miR-466f-3p together with the concordant up-regulation of Vegfa and Nrp2, that sustains the mesenchymal phenotype of SHH MB CSCs.

Embryonal central nervous system tumor in the brain of a goose

Embryonal central nervous system (CNS) tumor is a rare malignant neoplasm that arises from the neural crest. Herein we describe an embryonal tumor in the brain of an adult male domestic goose ( Anser anser) that was euthanized after a short history of wandering and lethargy. Grossly, a focal, bright-red, soft plaque was present on the ventral aspect of the brain, extending from the optic chiasm to the midbrain, as well as into the dorsal neuroparenchyma. Histologically, the nodule consisted of a poorly demarcated population of neoplastic cells arranged in streams and bundles, and occasionally palisading around small capillaries (pseudorosettes). Neoplastic cells were elongate and had scant, finely granular, eosinophilic cytoplasm, and elongate nuclei with dense chromatin. Mitoses were uncommon. Scattered foci of intratumoral necrosis and microvascular proliferation were present. Neoplastic cells were immunoreactive for doublecortin and neuronal nuclei. Ultrastructurally, neoplastic cells had elongated-to-polyhedral cytoplasm with short processes, scarce intermediate filaments, and small round mitochondria and rough endoplasmic reticulum. The cell membrane had varied numbers of intercellular anchoring-like junctions, and nuclei were round-to-elongate and had marginal aggregates of heterochromatin. Morphologic, immunohistochemical, and ultrastructural findings in our case are consistent with a poorly differentiated embryonal tumor.

Clinical, radiological, pathological and prognostic aspects of intraventricular oligodendroglioma: comparison with central neurocytoma

Studies comparing intraventricular oligodendroglioma (IVO) and central neurocytoma (CN) in terms of their clinical, radiological and pathological features are scarce. We, therefore, investigated the similarities and differences between these types of tumors to get a better understanding of how they may be more properly diagnosed and treated. The clinical manifestations, CT/MRI findings, pathological characteristics and clinical outcomes of 8 cases of IVOs and 12 cases of CNs were analyzed retrospectively. Both IVO and CN occurred most commonly in young adults and manifested with symptoms of increased intracranial pressure secondary to obstructive hydrocephalus. However, they were radiologically different in location (p = 0.007), diffusion-weighted imaging (p = 0.001), "scalloping" appearance (p = 0.006), flow void sign (p = 0.006) and ventricular wall invasion (p = 0.000). Histologically, significant differences in mitotic count (p = 0.008) and parenchymal infiltration (p = 0.01) were noted. Immunohistochemically, significant differences in the expression of Olig2 (p = 0.000), Syn (p = 0.01) and NeuN (p = 0.000) were observed. In addition, MIB-1 labeling index (p = 0.035) and case fatality rate (p = 0.021) of IVO were much higher than those of CN, while survival rate of IVO was much lower than that of CN (p = 0.028). IVO and CN are similar in onset age and clinical manifestations, but have different imaging and pathological features. Patients with IVOs may have a relatively poorer prognosis compared to those with CNs.

Immunohistochemical Characterization and Sensitivity to Human Adenovirus Serotypes 3, 5, and 11p of New Cell Lines Derived from Human Diffuse Grade II to IV Gliomas

BACKGROUND

Oncolytic adenoviruses show promise in targeting gliomas because they do not replicate in normal brain cells. However, clinical responses occur only in a subset of patients. One explanation could be the heterogenic expression level of virus receptors. Another contributing factor could be variable activity of tumor antiviral defenses in different glioma subtypes.

METHODS

We established a collection of primary low-passage cell lines from different glioma subtypes (3 glioblastomas, 3 oligoastrocytomas, and 2 oligodendrogliomas) and assessed them for receptor expression and sensitivity to human adenovirus (HAd) serotypes 3, 5, and 11p. To gauge the impact of antiviral defenses, we also compared the infectivity of the oncolytic adenoviruses in interferon (IFN)-pretreated cells with IFN-sensitive Semliki Forest virus (SFV).

RESULTS

Immunostaining revealed generally low expression of HAd5 receptor CAR in both primary tumors and derived cell lines. HAd11p receptor CD46 levels were maintained at moderate levels in both primary tumor samples and derived cell lines. HAd3 receptor DSG-2 was reduced in the cell lines compared to the tumors. Yet, at equal multiplicities of infection, the oncolytic potency of HAd5 in vitro in tumor-derived cells was comparable to HAd11p, whereas HAd3 lysed fewer cells than either of the other two HAd serotypes in 72 hours. IFN blocked replication of SFV, while HAds were rather unaffected.

CONCLUSIONS

Adenovirus receptor levels on glioma-derived cell lines did not correlate with infection efficacy and may not be a relevant indicator of clinical oncolytic potency. Adenovirus receptor analysis should be preferentially performed on biopsies obtained perioperatively.

Tinospora cordifolia ameliorates anxiety-like behavior and improves cognitive functions in acute sleep deprived rats

Sleep deprivation (SD) leads to the spectrum of mood disorders like anxiety, cognitive dysfunctions and motor coordination impairment in many individuals. However, there is no effective pharmacological remedy to negate the effects of SD. The current study examined whether 50% ethanolic extract of Tinospora cordifolia (TCE) can attenuate these negative effects of SD. Three groups of adult Wistar female rats - (1) vehicle treated-sleep undisturbed (VUD), (2) vehicle treated-sleep deprived (VSD) and (3) TCE treated-sleep deprived (TSD) animals were tested behaviorally for cognitive functions, anxiety and motor coordination. TSD animals showed improved behavioral response in EPM and NOR tests for anxiety and cognitive functions, respectively as compared to VSD animals. TCE pretreatment modulated the stress induced-expression of plasticity markers PSA-NCAM, NCAM and GAP-43 along with proteins involved in the maintenance of LTP i.e., CamKII-α and calcineurin (CaN) in hippocampus and PC regions of the brain. Interestingly, contrary to VSD animals, TSD animals showed downregulated expression of inflammatory markers such as CD11b/c, MHC-1 and cytokines along with inhibition of apoptotic markers. This data suggests that TCE alone or in combination with other memory enhancing agents may help in managing sleep deprivation associated stress and improving cognitive functions.

Histology and molecular aspects of central neurocytoma

Central neurocytoma (CN) is a well-differentiated tumor of neural cells occurring within the ventricles. It is composed of monomorphic cells with round, regular nuclei within clear cytoplasm and must be distinguished from other clear cell tumors. Immunohistochemical markers of CN that aid in diagnosis include synaptophysin and neuronal nuclear antigen. The molecular biology of these tumors is becoming increasingly elucidated, particularly with the use of microarray analyses. Several oncogenic pathways have been suggested by these studies. Although progress continues to be made, knowledge of CN has yet to dictate targeted therapies in treating patients with these tumors.

Novel Insights into NeuN: from Neuronal Marker to Splicing Regulator

Neuronal nuclei (NeuN) is a well-recognized "marker" that is detected exclusively in post-mitotic neurons and was initially identified through an immunological screen to produce neuron-specific antibodies. Immunostaining evidence indicates that NeuN is distributed in the nuclei of mature neurons in nearly all parts of the vertebrate nervous system. NeuN is highly conserved among species and is stably expressed during specific stages of development. Therefore, NeuN has been considered to be a reliable marker of mature neurons for the past two decades. However, this role has been challenged by recent studies indicating that NeuN staining is variable and even absent during certain diseases and specific physiological states. More importantly, despite the widespread use of the anti-NeuN antibody, the natural identity of the NeuN protein remained elusive for 17 years. NeuN was recently eventually identified as an epitope of Rbfox3, which is a novel member of the Rbfox1 family of splicing factors. This identification might provide a novel perspective on NeuN expression during both physiological and pathological conditions. This review summarizes the current progress on the biochemical identity and biological significance of NeuN and recommends caution when applying NeuN immunoreactivity as a definitive marker of mature neurons in certain diseases and specific physiological states.

Tinospora cordifolia Induces Differentiation and Senescence Pathways in Neuroblastoma Cells

Children diagnosed with neuroblastomas often suffer from severe side as well as late effects of conventional treatments like chemotherapy and radiotherapy. Recent advances in understanding of molecular pathways involved in cellular differentiation and apoptosis have helped in the development of new therapeutic approach based on differentiation-based therapy of malignant tumours. Natural medicines with their holistic therapeutic approach are known to selectively eliminate cancer cells thus provide a better substitute for the conventional treatment modes. The current study was aimed to investigate the anti-cancer potential of aqueous ethanolic extract of Tinospora cordifolia (TCE) using IMR-32 human neuroblastoma cell line as a model system. TCE is highly recommended in Ayurveda for its general body and metal health-promoting properties. TCE treatment was seen to arrest the majority of cells in G0/G1 phase and modulated the expression of DNA clamp sliding protein (PCNA) and cyclin D1. Further, TCE-treated cells showed differentiation as revealed by their morphology and the expression of neuronal cell specific differentiation markers NF200, MAP-2 and NeuN in neuroblastoma cells. The differentiated phenotype was associated with induction of senescence and pro-apoptosis pathways by enhancing expression of senescence marker mortalin and Rel A subunit of nuclear factor kappa beta (NFkB) along with decreased expression of anti-apoptotic marker, Bcl-xl. TCE exhibited anti-metastatic activity and significantly reduced cell migration in the scratched area along with downregulation of neural cell adhesion molecule (NCAM) polysialylation and secretion of matrix metalloproteinases (MMPs). Our data suggest that crude extract or active phytochemicals from this plant may be a potential candidate for differentiation-based therapy of malignant neuroblastoma cells.

[Modern molecular approaches to diagnosis and treatment of high-grade brain gliomas]

The review analyzes the current state of the problem of diagnosis and therapy of high-grade gliomas on the basis of the most promising present-day approaches. The diagnostic and treatment perspectives of the molecular genetic analysis of glioblastoma markers located on the tumor cell surface are considered. Gene therapy and the use of dendritic cells and oncolytic viruses are considered as the most interesting approaches to therapy of high-grade gliomas.

Multinodular and vacuolating neuronal tumors of the cerebrum: 10 cases of a distinctive seizure-associated lesion

We report 10 cases of a non-neurocytic, purely neuronal tumor affecting adults. Situated in the cerebral hemispheres, with 7 of 10 confined to the temporal lobes, most presented with seizures as their principal clinical manifestations. On magnetic resosnance imaging (MRI), the tumors generally appeared solid and non-contrast enhancing with minimal diffuse infiltration, edema, or mass effect. Six examples demonstrated internal nodularity. Microscopically, the tumor cells were largely distributed into discrete and coalescent nodules exhibiting varying degrees of matrix vacuolization, principally within the deep cortical ribbon and superficial subcortical white matter. Populating elements ranged from morphologically ambiguous to recognizably neuronal, with only two cases manifesting overt ganglion cell cytology. In all cases, tumor cells exhibited widespread nuclear immunolabeling for the HuC/HuD neuronal antigens, although expression of other neuronal markers, including synaptophysin, neurofilament and chromogranin was variable to absent. Tumor cells also failed to express GFAP, p53, IDH1 R132H, or CD34, although CD34-labeling ramified neural elements were present in the adjoining cortex of seven cases. Molecular analysis in a subset of cases failed to reveal DNA copy number abnormalities or BRAF V600E mutation. Follow-up data indicate that this unusual neuronal lesion behaves in benign, World Health Organization (WHO) grade I fashion and is amenable to surgical control.

Nogo-A: a useful marker for the diagnosis of oligodendroglioma and for identifying 1p19q codeletion

The differential diagnosis between oligodendrogliomas and other gliomas remains a critical issue. The aim of this study is to verify the diagnostic value of Olig-2, Nogo-A, and synaptophysin and their role in identifying 1p19q codeletion. A total of 168 cases of brain tumors were studied: 24 oligodendrogliomas, 23 anaplastic oligodendrogliomas, 2 oligoastrocytomas, 2 anaplastic oligoastrocytomas, 30 glioblastoma multiforme, 2 diffuse astrocytomas, 4 anaplastic astrocytomas, 10 pilocytic astrocytomas, 9 ependymomas, 12 anaplastic ependymomas, 10 central neurocytomas, 10 meningiomas, 10 choroid plexus papillomas, 10 dysembryoplastic neuroepithelial tumors, and 10 metastases. All cases were immunostained with Olig-2, Nogo-A, and synaptophysin. In 79 cases, the status of 1p/19q had already been assessed by fluorescence in situ hybridization. Thus, in selected cases, fluorescence in situ hybridization was repeated in areas with numerous Nogo-A-positive neoplastic cells. Nogo-A was positive in 18 (75%) of 24 oligodendrogliomas, 8 (80%) of 10 dysembryoplastic neuroepithelial tumors, 6 (20%) of 30 glioblastoma multiforme, and 2 (20%) of 10 pilocytic astrocytomas. Olig-2 stained 22 (91.6%) of 24 oligodendrogliomas and all dysembryoplastic neuroepithelial tumors but also 24 (80%) of 30 glioblastoma multiforme and 8 (80%) of 10 pilocytic astrocytomas. Finally, synaptophysin stained 13 (54.1%) of 24 oligodendrogliomas, 3 (10%) of 30 glioblastoma multiforme, 1 (10%) of 10 pilocytic astrocytomas, and all neurocytomas. Among the 79 tested cases, original fluorescence in situ hybridization showed 1p/19q codeletion in 12 (52.2%) of 23 oligodendrogliomas, 8 (38%) of 21 anaplastic oligodendrogliomas, and 1 (4%) of 25 glioblastoma multiforme. However, after carrying out the Nogo-A-driven fluorescence in situ hybridization, 1p/19q codeletion was observed in 8 additional cases. Nogo-A is more useful and specific than Olig-2 in differentiating oligodendrogliomas from other gliomas. Furthermore, using a Nogo-A-driven fluorescence in situ hybridization analysis, it is possible to identify a larger number of 1p19q codeletions in gliomas.

Olfactory neuroblastoma in dogs and cats--a histological and immunohistochemical analysis

Olfactory neuroblastoma (ONB) was identified in 13 dogs and nine cats. The tumours were subjected to microscopical examination and were graded using a human pathological grading system. In the canine and feline tumours there was more necrosis and higher mitotic activity (mitotic index and Ki67 labelling index) than reported in human ONB. Rosettes were a common feature of feline ONBs. A significant correlation was observed between the histological grade and the Ki67 labelling index. The histopathological diagnosis of ONB was confirmed immunohistochemically by demonstration of the neuronal marker neuron-specific enolase (NSE). Two other neuron-specific antibodies specific for microtubule-associated protein-2 (MAP-2) and neuronal nuclei antigen (NeuN) were evaluated. MAP-2 expression proved to have higher specificity than labelling for NSE. NeuN expression was less sensitive and of limited practical value.

Mutation-specific IDH1 antibody differentiates oligodendrogliomas and oligoastrocytomas from other brain tumors with oligodendroglioma-like morphology

Isocitrate dehydrogenase 1 (IDH1) mutations are frequent in astrocytomas, oligoastrocytomas and oligodendrogliomas. We previously reported the generation of a mutation-specific antibody that specifically detects R132H mutated IDH1 protein (clone H09). Here, we investigate the feasibility of H09 immunohistochemistry to differentiate between oligodendrogliomas/oligoastrocytomas and other tumors with similar morphology. A total of 274 brain tumors presenting with focal or extensive clear cell morphology were investigated. High numbers of H09-positive cases were observed in adult grade II oligodendrogliomas (67 of 74, 91%), grade III oligodendrogliomas (65 of 69, 94%), grade II oligoastrocytomas (11 of 14, 79%) and grade III oligoastrocytomas (10 of 11, 91%). All cases of pediatric oligodendrogliomas (n = 7), neurocytomas (n = 41, 35 central, 4 extraventricular, 2 cerebellar liponeurocytomas), dysembryoplastic neuroepithelial tumors (n = 21), clear cell ependymomas (n = 8), clear cell meningiomas (n = 9) as well as 12 primary glioblastomas with oligodendroglial differentiation and 5 pilocytic astrocytomas with oligodendroglial-like differentiation were negative for H09 immunohistochemistry. Three oligodendrogliomas with neurocytic differentiation had evidence of IDH1/IDH2 mutations either by H09 immunohistochemistry or direct sequencing. We conclude that in tumors with an oligodendroglioma-like morphology, binding of H09 is highly specific for oligodendrogliomas or oligoastrocytomas and substantially helps in the discrimination from other clear cell tumors. Negative H09 immunohistochemistry of an adult oligodendroglioma or oligoastrocytoma should prompt the consideration of other clear cell neoplasms. Further, our observations firmly assign oligodendrogliomas with neurocytic differentiation to the group of oligodendrogliomas and demonstrate that H09 is especially helpful for the difficult discrimination of such lesions from extraventricular neurocytomas.

Synchronous Choroid Plexus Papilloma of the Fourth Ventricle and Ependymoma of the Filum Terminale: Case Report

BACKGROUND AND IMPORTANCE:

We report the first case of synchronous choroid plexus papilloma of the fourth ventricle and myxopapillary ependymoma of the filum terminale. Both are papillary World Health Organization grade I tumors known to disseminate via cerebrospinal fluid pathways.

CLINICAL PRESENTATION:

A 65-year-old man presented with an incidental mass in the fourth ventricle found on a computed tomography scan of the head after a motor vehicle collision and an intradural mass of the filum terminale. The patient underwent resection of the fourth ventricle mass. After pathological diagnosis of a choroid plexus papilloma, the patient underwent resection of the spinal cord tumor.

CONCLUSION:

This case underscores the need for separate pathological diagnosis in a patient with an intradural spine lesion in the context of a benign intracranial lesion. We detail a panel of immunohistochemical markers essential for distinguishing the 2 papillary neuroectodermal tumors recovered in this case.

Differential distribution of erbB receptors in human glioblastoma multiforme: expression of erbB3 in CD133-positive putative cancer stem cells

Glioblastomas are the most common primary central nervous system tumors in adults, and they remain resistant to current treatments. erbB1 signaling is frequently altered in glioblastomas, suggesting thaterbB receptor family members may represent targets for molecular therapy. We performed a comprehensive analysis of erbB receptor and ligand expression profiles in a panel of 9 glioblastomas andcompared them to nonneoplastic cerebral tissue containing neocortex and adjacent white matter. Quantitative reverse transcription-polymerase chain reaction and Western blot analysis showed that erbB1signaling and erbB2 receptors exhibited highly variable deregulation profiles in the tumors, with patterns ranging from underexpression to overexpression; in contrast, erbB3 and erbB4 were downregulated. We next performed immunohistochemistry to determinethe distribution patterns of erbB receptors among the main neuralcell types in the tumors with special reference to the putative tumor stem cell population. Results revealed intertumoral and intratumoral heterogeneity in all 4 erbB expression profiles, but each receptor exhibited a distinct distribution pattern among glial fibrillary acidic protein-, Olig2-, NeuN-, and CD133-positive populations. Although erbB1 immunoreactivity was detected in only small subsets of CD133-positive putative tumor stem cells, erbB3 immunoreactivity was prominent in this population, suggesting that erbB3 may represent a new potential therapeutic target.

Pleiotropic role for MYCN in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Sonic Hedgehog (SHH) signaling drives a minority of MB, correlating with desmoplastic pathology and favorable outcome. The majority, however, arises independently of SHH and displays classic or large cell anaplastic (LCA) pathology and poor prognosis. To identify common signaling abnormalities, we profiled mRNA, demonstrating misexpression of MYCN in the majority of human MB and negligible expression in normal cerebella. We clarified a role in pathogenesis by targeting MYCN (and luciferase) to cerebella of transgenic mice. MYCN-driven MB showed either classic or LCA pathologies, with Shh signaling activated in approximately 5% of tumors, demonstrating that MYCN can drive MB independently of Shh. MB arose at high penetrance, consistent with a role for MYCN in initiation. Tumor burden correlated with bioluminescence, with rare metastatic spread to the leptomeninges, suggesting roles for MYCN in both progression and metastasis. Transient pharmacological down-regulation of MYCN led to both clearance and senescence of tumor cells, and improved survival. Targeted expression of MYCN thus contributes to initiation, progression, and maintenance of MB, suggesting a central role for MYCN in pathogenesis.

Expression of PROX1 Is a common feature of high-grade malignant astrocytic gliomas

PROX1 is a prospero-related transcription factor that plays a critical role in the development of various organs including the mammalian lymphatic and central nervous systems; it controls cell proliferation and differentiation through different transcription pathwaysand has both oncogenic and tumor-suppressive functions. We investigated PROX1 expression patterns in 56 human astrocytic gliomas of different grades using immunohistochemistry. An average of 79% of cells in World Health Organization Grade IV (glioblastoma, n = 15) and 57% of cells in World Health Organization Grade III (anaplastic astrocytoma, n = 13) were strongly PROX1 positive; low-grade diffuse astrocytomas (Grade II, n = 13) had 21% of cells that were strongly positive; Grade I tumors (n = 15) had 1.5%; and non-neoplastic brain tissue (n = 15) had 3.7% of cells that were PROX1 positive. Double immunolabeling showed that PROX1+ cells in glioblastomas frequently coexpressed early neuronal proteins MAP2 and betaIII-tubulin but not the mature neuronal marker protein NeuN. Analyses of coexpression with proliferation markers suggest that PROX1+ cells have a marginally lower rate of proliferation than other tumor cells but are still mitotically active. We conclude that PROX1 may constitute a useful tool for the diagnosis and grading ofastrocytic gliomas and for distinguishing Grade III and Grade IV tumors from Grade I and Grade II tumors.

In pursuit of prognostic factors in children with pilocytic astrocytomas

OBJECTIVE

This study described a 23-year experience in the treatment of children with pilocytic astrocytomas (piloA) with the aim of identifying putative clinical, histopathological, and/or immunohistochemical features that could be related to the outcome of these patients.

METHODS

Clinical data of 31 patients under 18 years of age with piloA were obtained from 1984 to 2006.

RESULTS

The mean age at the time of surgery was 7.8 +/- 4.2 years (1 to 17 years), and the mean follow-up was 5.7 +/- 5.4 years (1 to 20 years). The most common site of tumor formation was the cerebellum (17), followed by brainstem (4), optic chiasmatic hypothalamic region (4), cerebral hemisphere (3), cervical spinal cord (2), and optic nerve (1). Gross total resection (GTR) was achieved in 23 (74.1%), mainly in those with tumors located in the cerebellum and cerebral hemispheres (P = 0.02). The global mortality rate was 6.4%. Nine patients were reoperated. Rosenthal fibers, eosinophilic granular bodies, microvascular proliferation, and lymphocytic infiltration were observed in most cases. The mean Ki-67LI was 4.4 +/- 4.5%. In all cases, Gal-3 expression in tumor cells was observed with variable staining pattern.

CONCLUSIONS

Aside from GTR, no other clinical, histopathological, or immunohistochemical features were found to be related to the prognosis. We postulate that strict follow-up is recommended if piloA is associated with high mitotic activity/Ki67-LI, or if GTR cannot be achieved at surgery. Tumor recurrence or progression of the residual lesion should be strictly observed. In some aspects, childhood piloA remains an enigmatic tumor.

Identification of neuronal nuclei (NeuN) as Fox-3, a new member of the Fox-1 gene family of splicing factors

NeuN (neuronal nuclei) is a neuron-specific nuclear protein which is identified by immunoreactivity with a monoclonal antibody, anti-NeuN. Anti-NeuN has been used widely as a reliable tool to detect most postmitotic neuronal cell types in neuroscience, developmental biology, and stem cell research fields as well as diagnostic histopathology. To date, however, the identity of its antigen, NeuN itself, has been unknown. Here, we identify NeuN as the Fox-3 gene product by providing the following evidence: 1) Mass spectrometry analysis of anti-NeuN immunoreactive protein yields the Fox-3 amino acid sequence. 2) Recombinant Fox-3 is recognized by anti-NeuN. 3) Short hairpin RNAs targeting Fox-3 mRNA down-regulate NeuN expression. 4) Fox-3 expression is restricted to neural tissues. 5) Anti-Fox-3 immunostaining and anti-NeuN immunostaining overlap completely in neuronal nuclei. We also show that a protein cross-reactive with anti-NeuN is the synaptic vesicle protein, synapsin I. Anti-NeuN recognizes synapsin I in immunoblots with one order of magnitude lower affinity than Fox-3, and does not recognize synapsin I using immunohistology. Fox-3 (also called hexaribonucleotide-binding protein 3 and D11Bwg0517e) contains an RNA recognition motif and is classified as a member of the Fox-1 gene family that binds specifically to an RNA element, UGCAUG. We demonstrate that Fox-3 functions as a splicing regulator using neural cell-specific alternative splicing of the non-muscle myosin heavy chain II-B pre-mRNA as a model. Identification of NeuN as Fox-3 clarifies an important element of neurobiology research.

Immunohistochemical expression of markers Ki-67, neun, synaptophysin, p53 and HER2 in medulloblastoma and its correlation with clinicopathological parameters

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. The alterations found include: presence of oncoproteins p53 and HER2, elevated mitotic index, and presence of neuronal differentiation. The aim of this study was to determine the immunohistochemical expression of markers Ki-67, NeuN, synaptophysin, HER2 and p53 in 40 MB samples and their correlation with clinicopathologic parameters and survival. In 29 patients (72.5%), >20% of cells were positive for Ki-67. Males showed greater ki-67 expression (p=0.02) and smaller survival rates (p=0.002). NeuN and synaptophysin were negative in 16 (40%) and 8 (20%) cases, respectively. P53 was positive in 18 (45%) cases, with 11 (61%) weakly positive and 7 (39%) strongly positive. HER2 was positive in 23 (57.5%) of the samples and did not show statistical association with survival (p=0.07).

Chromosome 1p and 19q deletions in malignant glioneuronal tumors with oligodendroglioma-like component

Malignant glioneuronal tumors (MGNT) are suggested to be a new entity of glioma defined morphologically as any malignant glioma showing immunohistoichemical evidence of neuronal differentiation. We encountered seven cases of MGNT with oligodendroglioma-like component and investigated alternations of chromosome 1p and 19q in these tumors. Seven patients ranged from 33 to 62 years of age, four females and three males. Immunohistochemical study of these tumors was performed using neuronal markers (synaptophysin, neurofilament, beta-tubulin, chromogranin A and NeuN), astrocytic marker (GFAP) and Ki-67. We undertook a molecular cytogenetic study of tumor specimens obtained from seven patients using fluorescence in situ hybridization (FISH) with DNA probes mapping to chromosome 1p36, 1q25, 19p13 and 19q13. Histologically, these tumors resembled anaplastic oligodendroglioma. Immunohistochemically, tumor cells were immunoreactive for synaptophysin (7/7), neurofilament (6/7), beta-tubulin (5/7), chromogranin A (4/7), NeuN (2/7) and GFAP (7/7). The Ki-67 labeling index ranged from 4.5% to 20.7%. FISH analysis demonstrated either 1p or 19q deletion in all seven cases (100%) and both 1p and 19q deletions in five cases (71%). The 1p deletion was detected in six of seven cases (86%) and 19q deletion was also detected in six (86%). 1p and 19q deletions were present in MGNT, especially those with oligodendroglial components. We suggest that the oligodendroglial-like feature was associated with not only 1p or 19q loss but also differentiation along neuronal cell lines as a factor of favorable prognosis in glial tumors. It is inappropriate to make a diagnosis of oligodendroglioma based only on morphological resemblance to oligodendroglia.

The Differential Diagnosis of Central Nervous System Tumors: A Critical Examination of Some Recent Immunohistochemical Applications

Context.—As we write, novel antibodies that may well alter the routine practice of surgical neuropathology are in development, characterization, and the early stages of clinical use. These will be used for purposes of tumor subclassification, as prognostic markers, as identifiers of potential therapeutic targets, and as predictors of treatment response.

Objective.—To provide for nonspecialists a critical assessment of the peer-reviewed literature (necessarily colored by our own experience) as it pertains to several immunohistochemical reagents that have been recently forwarded as adjuncts to the histologic typing of central nervous system tumors.

Data Sources.—We address in these pages only antibodies that are commercially available, that have been the subjects of multiple published series, and that we have had occasion to use in the course of everyday problem solving.

Conclusions.—Discussion concentrates on the use of 4 antibodies: BAF47 in the diagnosis of atypical teratoid/ rhabdoid tumor, OCT4 in intracranial germinoma, β-catenin in craniopharyngioma, and NeuN as a marker of neuronal differentiation in neuroepithelial neoplasms.

Widespread immunoreactivity for neuronal nuclei in cultured human and rodent astrocytes

The monoclonal antibody (mAb) neuronal nuclei (NeuN) labels the nuclei of mature neurons in vivo in vertebrates. NeuN has also been used to define post-mitotic neurons or differentiating neuronal precursors in vitro. In this study, we demonstrate that the NeuN mAb labels the nuclei of astrocytes cultured from fetal and adult human, newborn rat, and embryonic mouse brain tissue. A non-neuronal fibroblast cell line (3T3) also displayed NeuN immunoreactivity. We confirmed that NeuN labels neurons but not astrocytes in sections of P10 rat brain. Western blot analysis of NeuN immunoreactive species revealed a distribution of bands in nucleus-enriched fractions derived from the different cell lines that was similar, but not identical to adult rat brain homogenates. We then examined the hypothesis that the glial fibrillary acidic protein/NeuN-double positive population of cells might correspond to neuronal precursors. Although the NeuN-positive astrocytes were proliferating, no evidence of neurogenesis was detected. Furthermore, expression of additional neuronal precursor markers was not detected. Our results indicate that primary astrocytes derived from mouse, rat, and human brain express NeuN. Our findings are consistent with NeuN being a selective marker of neurons in vivo, but indicate that studies utilizing NeuN-immunoreactivity as a definitive marker of post-mitotic neurons in vitro should be interpreted with caution.

Secretagogin expression in tumours of the human brain and its coverings

Secretagogin is a recently described calcium-binding protein, which is expressed in some neurons of the human brain. In this study we systematically investigated secretagogin expression in 245 tumours of the human brain and its coverings using immunohistochemistry. We found focal or widespread secretagogin expression in tumour cells in 1/18 oligoastrocytomas, 1/19 oligodendrogliomas, 2/20 anaplastic oligodendrogliomas, 2/9 ependymomas, 2/11 anaplastic ependymomas, 2/10 glioblastomas, 3/11 gangliogliomas and 1/2 anaplastic gangliogliomas, 10/10 central neurocytomas, 5/10 classic medulloblastomas, 4/5 desmoplastic medulloblastomas, 3/5 large cell/anaplastic medulloblastomas, 3/5 neuroblastomas, 3/10 meningiomas, 2/10 haemangioblastomas, and 13/19 pituitary adenomas. Further, we observed secretagogin expression in endothelial cells in 5/10 meningiomas, 2/5 haemangiopericytomas, and 2/10 haemangioblastomas. We detected no secretagogin expression in fibrillary astrocytoma, pilocytic astrocytoma, DNT, pineocytoma, pineoblastoma, subependymal giant cell astrocytoma (SEGA), atypical teratoid/rhabdoid tumour (AT/RT), or primary central nervous system lymphoma (PCNSL). We conclude that secretagogin is differentially expressed in human neuronal, glial, and embryonal brain tumours, meningial neoplasms and pituitary adenomas. Our findings indicate that secretagogin is involved in the calcium metabolism of tumour cells and endothelial cells in a subset of neoplasms of the brain and its coverings. Anti-secretagogin immunohistochemistry does not seem to be helpful in most differential diagnostic situations in surgical neuropathology.

OLIG2 is a useful immunohistochemical marker in differential diagnosis of clear cell primary CNS neoplasms

AIMS

To analyse OLIG2 expression in clear cell primary central nervous system (CNS) tumours to clarify the diagnostic usefulness of OLIG2 immunohistochemistry in this subset of brain tumours.

METHODS AND RESULTS

We analysed OLIG2 expression in 60 oligodendroglial neoplasms (57 with and three without chromosome 1p aberration), 10 central neurocytomas, 10 clear cell ependymomas, nine dysembryoplastic neuroepithelial tumours (DNTs) and two clear cell meningiomas using immunohistochemistry. Additionally, we analysed oligodendroglial neoplasms with numerous gliofibrillary and minigemistocytic oligodendrocytes for OLIG2/glial fibrillary acidic protein (GFAP) coexpression and central neurocytoma for coexpression of neurone-specific nuclear protein (NeuN) and OLIG2 using double immunofluorescent labelling and confocal laser scanning microscopy. All oligodendroglial neoplasms and DNTs showed widespread OLIG2 expression. Eight of 10 central neurocytomas, all clear cell meningiomas and 8/10 clear cell ependymomas were negative for OLIG2. Two of 10 central neurocytomas and 2/10 clear cell ependymomas showed focal OLIG2 expression. We found prominent coexpression of GFAP and OLIG2 in gliofibrillary and minigemistocytic oligodendrocytes. Further, we found coexpression of NeuN and OLIG2 in single cells in central neurocytoma.

CONCLUSIONS

Widespread OLIG2 expression discriminates oligodendroglial neoplasms or DNTs from other clear cell primary brain tumour types. In clear cell primary brain tumours lacking OLIG2 expression, differential diagnosis may require additional immunohistochemical markers.