The astroblastoma and its possible cytogenic relationship to the tanycyte. An electron microscopic, immunohistochemical, tissue- and organ-culture study

High-Grade Astroblastoma in a Young Female: An Enigma with a Rare Cautionary Tale

Astroblastoma is an uncommon neuroepithelial primary brain neoplasm with speculative histopathological origin and unpredictable clinical behavior. They can be easily misdiagnosed, as they are rarely encountered in clinical practice and share common radiological and histopathologic appearances with other glial neoplasms. Herein, we report a case of high-grade astroblastoma in a 27-year-old female with complaints of seizures and loss of consciousness, which was misdiagnosed as atypical meningioma on neuroimaging, due to its rarity and superficial cortical location appearing as extra-axial mass. Although intraoperative findings were also of an extra-axial tumor, the histology and immunophenotype was of an astroblastoma; thus, highlighting the role of histopathology and immunohistochemistry.

Astroblastomas exhibit radial glia stem cell lineages and differential expression of imprinted and X-inactivation escape genes

Astroblastomas (ABs) are rare brain tumors of unknown origin. We performed an integrative genetic and epigenetic analysis of AB-like tumors. Here, we show that tumors traceable to neural stem/progenitor cells (radial glia) that emerge during early to later brain development occur in children and young adults, respectively. Tumors with MN1-BEND2 fusion appear to present exclusively in females and exhibit overexpression of genes expressed prior to 25 post-conception weeks (pcw), including genes enriched in early ventricular zone radial glia and ependymal tumors. Other, histologically classic ABs overexpress or harbor mutations of mitogen-activated protein kinase pathway genes, outer and truncated radial glia genes, and genes expressed after 25 pcw, including neuronal and astrocyte markers. Findings support that AB-like tumors arise in the context of epigenetic and genetic changes in neural progenitors. Selective gene fusion, variable imprinting and/or chromosome X-inactivation escape resulting in biallelic overexpression may contribute to female predominance of AB molecular subtypes.

Cerebral astroblastoma with oligodendroglial-like cells: A case report

RATIONALE

Astroblastoma is a rare tumor of the central nervous system with uncertain biological behavior and origin. Its histopathological features have been well established, while, to our knowledge, astroblastoma with oligodendroglial-like cells have not been reported.

PATIENT CONCERNS

A 15-year-old girl presented with nausea, vomiting, headache, and visual disturbance.

DIAGNOSIS

Magnetic resonance imaging revealed a large neoplasm in the left temporal. Histologically, the tumor showed solid and pseudopapillary structure. Immunohistochemical staining showed that the tumor cells were positive for glial fibrillary acidic protein and vimentin. The oligodendroglial-like cells were positive for glial fibrillary acidic protein, vimentin, and oligodendrocyte transcription factor 2. The antigen KI67 labeling index was about 4%. Sequencing for isocitrate dehydrogenase (IDH) 1 codon 132 and IDH2 codon 172 gene mutations showed negative results. Furthermore, fluorescent analysis revealed neither 1p nor 19q deletion in the lesion. Based on these findings, the girl was finally diagnosed as astroblastoma.

INTERVENTIONS

A craniotomy with total excision of the tumor was performed.

OUTCOMES

The follow-up time was 1 year, no evidence of disease recurrence was found in magnetic resonance imaging.

LESSONS

Cerebral astroblastoma with oligodendroglial-like cells is a clinically rare tumor of central nervous system. Clear distinction and diagnosis are critical.

Well-differentiated Astroblastoma with Both Focal Anaplastic Features and a Meningioma 1 Gene Alteration

A 6-year-old female was incidentally found to have a brain tumor. Magnetic resonance imaging (MRI) demonstrated a gadolinium-enhanced mass in the left parietal lobe. We performed gross total resection with the assistance of fluorescent guidance by 5-aminolevulinic acid (5-ALA). A histological examination of the tumor specimen showed well-differentiated astroblastic features with focal anaplasia. Fluorescence in situ hybridization (FISH) revealed meningioma 1 (MN1) gene alteration and supported our diagnosis. She received local radiotherapy and oral temozolomide followed by maintenance temozolomide chemotherapy, and the tumor was well controlled without any neurological deficit for 27 months. Our case is considered to be valuable since it describes a patient who is diagnosed to have a well-differentiated astroblastoma with both focal anaplastic features and MN1 gene rearrangement. A larger study is warranted to establish evidence supporting the diagnosis and treatment of astroblastoma with molecular characteristic features. MN1 alteration will be a diagnostic marker for astroblastoma in the future.

Extra-axial anaplastic astroblastoma in a 67-year-old woman

Astroblastoma is a rare glial neoplasia of the central nervous system. It is histologically defined by the presence of neoplastic cells with non- or slightly tapering processes arranged around blood vessels (astroblastic rosettes) and conventionally subdivided into well-differentiated and anaplastic. It commonly affects children and young adults, although cases and due to its superficial location in the brain cortex, it can mimic an extra-axial mass on magnetic resonance imagining. Herein, we describe a unique case of pure extra-axial anaplastic astroblastoma in an elderly woman. Awareness that astroblastoma may be also extra-axial and affect older subjects, may be helpful for its identification and differential diagnosis toward more common entities at this site and age of onset, and for appropriate therapeutic management as well.

Astroblastoma - a rare and challenging tumor: a case report and review of the literature

Background

Astroblastoma is a controversial and an extremely rare central nervous system neoplasm. Although its histogenesis has been clarified recently, controversies exist regarding its cellular origin and validity as a distinct entity. Because of its extreme rarity and because its common features are shared with other glial neoplasms, this tumor is prone to misdiagnosis and remains challenging not only in terms of diagnosis and classification but also in the subsequent management. This case report describes a new case of astroblastoma. It discusses clinical, radiologic, pathological, and therapeutic features and differential diagnosis of this rare neoplasm, with a review of the recent literature.

Case presentation

We report the case of an 8-year-old Moroccan girl who presented with a 1-year history of epileptic seizure, headache, and decreased visual acuity. Cranial magnetic resonance imaging revealed a right occipito-temporal mass. A tumor resection was performed and histological examination combined with immunohistochemical study confirmed the diagnosis of low-grade astroblastoma.

Conclusions

Astroblastoma is a very rare primary brain tumor. Its diagnosis is often challenging because of the astroblastic aspects that can be found in astrocytic tumors, in ependymomas, and in non-neuroepithelial tumors. Considerable confusion surrounds its histogenesis and classification. The low incidence rate makes it difficult to conduct studies to examine tumor characteristics.

Astroblastoma: a distinct tumor entity characterized by alterations of the X chromosome and MN1 rearrangement

Astroblastoma is a rare, enigmatic tumor of the central nervous system (CNS) which shares some clinicopathologic aspects with other CNS tumors, especially ependymoma. To further clarify the nature of astroblastoma, we performed clinicopathologic and molecular genetic studies on eight cases of astroblastoma. The median age of the patients was 14.5 years, ranging from 5 to 60 years, and seven of the patients were female. All tumors arose in the cerebral hemisphere and radiologically appeared to be well-bordered, nodular tumors often associated with cystic areas and contrast-enhancement. Six of the seven patients with prognosis data survived without recurrences during the follow-up periods ranging from six to 76 months. One patient had multiple recurrences and died six years later. All tumors exhibited salient microscopic features, such as being well demarcated from the surrounding brain tissue, perivascular arrangement of epithelioid tumor cells (represented by "astroblastic" pseudorosettes, trabecular alignment, and pseudopapillary patterns), and hyalinized blood vessels. Immunoreactivity for GFAP, S-100 protein, Olig2, and EMA was variably demonstrated in all tumors, and IDH1 R132H and L1CAM were negative. Array comparative genomic hybridization revealed numerous heterozygous deletions on chromosome X in the four tumors studied, and break-apart fluorescence in situ hybridization demonstrated rearrangement of MN1 in five tumors with successful testing. The characteristic clinicopathologic and genetic findings support the idea that astroblastoma is distinct from other CNS tumors, in particular, ependymoma. In addition, MN1 rearrangement and aberrations of chromosome X may partly be involved in the pathogenesis of astroblastoma.

Patterns of care and survival outcomes in patients with astroblastoma: an individual patient data analysis of 152 cases

BACKGROUND

Astroblastoma (AB) is a rare tumor with significant dilemma regarding diagnostic criteria, behavior, and optimum treatment.

MATERIALS AND METHODS

We searched PubMed, Google Search, and Cochrane Library for eligible studies with the following search words: astroblastoma, high-grade astroblastoma, and anaplastic astroblastoma till July 1, 2016, published in English language and collected data regarding age, sex, site of disease, pathological grade, treatment received, and survival.

RESULTS

Data of 152 patients were retrieved from 63 publications. Median age was 16 years (range 0-71). Females were affected twice more frequently than male (70.3 vs. 29.7%). Tumors were most commonly located in the frontal (39%) followed by parietal lobe (26.7%). Fifty-two and 25% of the patients had headache and seizure at presentation, 76.3% of the patients underwent a gross total resection, 41 out of 89 had a high-grade tumor, and 56 patients received adjuvant radiation with a median dose of 54 Gy (range 20-72). Adjuvant chemotherapy was used in 23 patients. Temozolomide was the most common drug used in 30% of the patients. A combination of cisplatin, etoposide with vincristine, or ifosfamide was used in 17%. Median follow-up duration was 37 months (range 1-238). Median progression-free survival and OS were 36 and 184 months, respectively. Patients with a higher-grade tumor had significantly worse OS with HR 5.260 and p = 0.001. Forty patients experienced local progression. Sixty-five percent patients underwent surgery while 50% underwent radiation as salvage.

CONCLUSION

AB has two distinct grades with higher-grade tumors having significantly poor survival. Maximal safe surgery followed by adjuvant radiation and temozolomide should be advocated for these tumors.

A Pediatric Tumor Found Frequently in the Adult Population: A Case of Anaplastic Astroblastoma in an Elderly Patient and Review of the Literature

Astroblastomas are rare, potentially curable primary brain tumors which can be difficult to diagnose. We present the case of astroblastoma in a 73-year-old male, an atypical age for this tumor, more classically found in pediatric and young adult populations. Through our case and review of the literature, we note that this tumor is frequently reported in adult populations and the presentation of this tumor in the elderly is well described. This tumor is an important consideration in the differential diagnosis when managing both pediatric and adult patients of any age who present with the imaging findings characteristic of this rare tumor.

A comprehensive analysis identifies BRAF hotspot mutations associated with gliomas with peculiar epithelial morphology

Brain tumors harbor various BRAF alterations, the vast majority of which are the BRAF kinase-activating V600E mutation. BRAF mutations are most frequently detected in certain subtypes of low-grade glioma, such as pilocytic astrocytoma (PA), pleomorphic xanthoastrocytoma (PXA), ganglioglioma (GG) and dysembryoplastic neuroepithelial tumor (DNT). However, it is unclear whether gliomas harboring BRAF mutations can be invariably regarded as these glioma subtypes or their derivatives. To address this question, we analyzed 274 gliomas in our institutional case series. We performed high-resolution melting analyses and subsequent direct Sanger sequencing on DNA isolated from snap-frozen tumor tissues. As expected, BRAF mutations were detected in the aforementioned low-grade gliomas: in 4/27 PAs, 2/3 PXAs, 4/8 GGs, and 1/6 DNTs. In addition to these gliomas, 1/2 astroblastomas (ABs) and 2/122 glioblastomas (GBs) harbored BRAF mutations. Pathological investigation of the two GBs revealed that one was a GB displaying epithelial features that presumably arose from a precedent GG, whereas the other GB, which harbored a rare G596 A mutation, showed marked epithelial features, including astroblastic rosettes. Our results indicate that in addition to being present in established BRAF-associated gliomas, BRAF mutations might be associated with epithelial features in high-grade gliomas, including sheet-like arrangement of polygonal tumor cells with a plump cytoplasm and astroblastic rosettes, and thus could potentially serve as a genetic marker for these features.

Morphological and molecular features of astroblastoma, including BRAFV600E mutations, suggest an ontological relationship to other cortical-based gliomas of children and young adults

BACKGROUND

Astroblastomas (ABs) are rare glial tumors showing overlapping features with astrocytomas, ependymomas, and sometimes other glial neoplasms, and may be challenging to diagnose.

METHODS

We examined clinical, histopathological, and molecular features in 28 archival formalin-fixed, paraffin-embedded AB cases and performed survival analyses using Cox proportional hazards and Kaplan-Meier methods.

RESULTS

Unlike ependymomas and angiocentric gliomas, ABs demonstrate abundant distinctive astroblastic pseudorosettes and are usually Olig2 immunopositive. They also frequently exhibit rhabdoid cells, multinucleated cells, and eosinophilic granular material. They retain immunoreactivity to alpha thalassemia/mental retardation syndrome X-linked, are immunonegative to isocitrate dehydrogenase-1 R132H mutation, and only occasionally show MGMT promoter hypermethylation differentiating them from many diffuse gliomas. Like pleomorphic xanthoastrocytoma, ganglioglioma, supratentorial pilocytic astrocytoma, and other predominantly cortical-based glial tumors, ABs often harbor the BRAF^V600E mutation, present in 38% of cases tested (n = 21), further distinguishing those tumors from ependymomas and angiocentric gliomas. Factors correlating with longer patient survival included age less than 30 years, female gender, absent BRAF^V600E , and mitotic index less than 5 mitoses/10 high-power fields; however, only the latter was significant by Cox and Kaplan-Meier analyses (n = 24; P = .024 and .012, respectively). This mitotic cutoff is therefore currently the best criterion to stratify tumors into low-grade ABs and higher-grade anaplastic ABs.

CONCLUSIONS

In addition to their own characteristic histological features, ABs share some molecular and histological findings with other, possibly ontologically related, cortical-based gliomas of mostly children and young adults. Importantly, the presence of BRAF^V600E mutations in a subset of ABs suggests potential clinical utility of targeted anti-BRAF therapy.

Low-grade Glial Tumor with Features of Astroblastoma in a Dog

A 12-year-old, neutered, male Belgian Malinois/Great Dane cross dog presented with a 5-month history of weakness and lack of endurance followed by acute onset of rear limb ataxia. At autopsy, a 9 x 16 mm, multilobular, firm, white to tan, expansile mass was found in the cerebellum. Mild dilatation of the lateral ventricles was also noted. Histologically, there was a well-demarcated glial neoplasm composed of medium-sized astrocytic elements that had homogeneous cytoplasm, sometimes with globular eosinophilic inclusions, irregular peripherally located nuclei with a single nucleolus, and short cytoplasmic processes. Prominent peri-vascular pseudorosettes with cellular processes in contact with blood vessels were present. Some blood vessels exhibited hyalinized walls. Mitotic figures were not observed. Immunohistochemically, neoplastic cells expressed glial fibrillary acidic protein and vimentin. These features are consistent with an astroblastoma. This is the first clinicopathologic correlation and detailed description of a low-grade glial tumor with features of astroblastoma in a dog.

Genomic characterization of recurrent high-grade astroblastoma

Astroblastomas are rare primary brain tumors, diagnosed based on histologic features. Not currently assigned a WHO grade, they typically display indolent behavior, with occasional variants taking a more aggressive course. We characterized the immunohistochemical characteristics, copy number (high-resolution array comparative genomic hybridization, OncoCopy) and mutational profile (targeted next-generation exome sequencing, OncoPanel) of a cohort of seven biopsies from four patients to identify recurrent genomic events that may help distinguish astroblastomas from other more common high-grade gliomas. We found that tumor histology was variable across patients and between primary and recurrent tumor samples. No common molecular features were identified among the four tumors. Mutations commonly observed in astrocytic tumors (IDH1/2, TP53, ATRX, and PTEN) or ependymoma were not identified. However one case with rapid clinical progression displayed mutations more commonly associated with GBM (NF1(N1054H/K63)*, PIK3CA(R38H) and ERG(A403T)). Conversely, another case, originally classified as glioblastoma with nine-year survival before recurrence, lacked a GBM mutational profile. Other mutations frequently seen in lower grade gliomas (BCOR, BCORL1, ERBB3, MYB, ATM) were also present in several tumors. Copy number changes were variable across tumors. Our findings indicate that astroblastomas have variable growth patterns and morphologic features, posing significant challenges to accurate classification in the absence of diagnostically specific copy number alterations and molecular features. Their histopathologic overlap with glioblastoma will likely confound the observation of long-term GBM "survivors". Further genomic profiling is needed to determine whether these tumors represent a distinct entity and to guide management strategies.

Hemorrhage in astroblastoma: An unusual manifestation of an extremely rare entity

Astroblastoma is a rare tumor of glial origin with characteristics of both astrocytoma and ependymoma. It is usually seen in children and young adults, and is peripherally located, well circumscribed, of solid-cystic composition and with heterogeneous contrast enhancement. Histopathology reveals perivascular pseudorosette formation and thick hyalinised vessels. Hemorrhage in astroblastoma is unusual and rarely described in literature. We report two patients with astroblastoma who presented with hemorrhage and discuss the natural history, radiological findings, pathophysiology of hemorrhage and histopathological characteristics. We emphasize the importance of early suspicion in peripherally located lesions with bleeding.

Lack of IDH1 mutation in astroblastomas suggests putative origin from ependymoglial cells?

Astroblastomas are extremely rare neuroepithelial tumors of uncertain histogenesis, affecting children and young adults, and constitute a new addition to the WHO 2000 classification of CNS tumors. We report the largest series of nine cases diagnosed in a single institute over the last 13 years and review published literature. Mean age at presentation was 12.8 years (range: 22 months to 27years). Seven out of nine cases were supratentorial (frontal/frontoparietal - three, parieto-occipital - three, parafalcine - one), one was intraventricular and another was optochaismatic/suprasellar. Five cases were high grade (anaplastic) astroblastomas with Ki-67 labeling index of 8-10%. Immunohistochemical and ultrastructural evidence suggesting origin from cells intermediate between ependymocytes and astrocytes is presented. The histogenetic origin of these tumors remains speculative. But the lack of Isocitrate dehydrogenase 1 (IDH1) mutation as detected by immunohistochemistry in this study, which is similar to ependymomas supports putative origin from ependymoglial cells. Out of the nine cases, recurrence was noted in one case, 12 months after gross total resection with progression to high grade in the recurrent tumor. There is no recommended treatment protocol due to the rarity of this entity and prognostic factors are yet to be established.

Astroblastoma: beside being a tumor entity, an occasional phenotype of astrocytic gliomas?

The diagnosis of astroblastoma is based on a typical histological aspect with perivascular distribution of cells sending cytoplasmic extensions to the vessels and vascular hyalinization. These criteria are useful for standardizing the identification of the tumor, but, in spite of this, there are discrepancies in the literature concerning the age distribution and the benign or malignant nature of the tumor. Three cases are discussed in this study: Case 1 was a typical high-grade astroblastoma; Case 2 was an oligodendroglioma at the first intervention and an oligoastrocytoma at the second intervention with typical perivascular arrangements in the astrocytic component; Case 3 was a gemistocytic glioma with malignant features and typical perivascular arrangements. Genetic analysis showed genetic alterations that are typical of gliomas of all malignancy grades. Using the neurosphere assay, neurospheres and adherent cells were found to have developed in Case 1, while adherent cells only developed in Case 2, in line with the stemness potential of the tumors. The cases are discussed in relation to their diagnostic assessment as astroblastoma, and it is hypothesized that the typical perivascular distribution of cells may not indicate a separate and unique tumor entity, but may be a peculiarity that can be acquired by astrocytic gliomas when an unknown cause from the tumor microenvironment influences the relationship between vessels and tumor cells.

Intraventricular Astroblastoma in an Infant: A Case Report and Review of the Literature

Astroblastomas are rare intracranial tumours of uncertain origin and are commonly present in the supratentorial compartment. Astroblastomas often affect children and young adults. Their occurrence in an intraventricular location, in an infant, is extremely uncommon. We describe a 1-year-old boy who presented with features of raised intracranial pressure. An MRI scan revealed an intralateral ventricular tumour. Complete excision was performed. Its histopathological examination revealed features consistent with astroblastoma. A follow-up MRI scan after 9 months did not show any residual tumour, and the patient was followed up without any adjuvant therapy. The radiological and histopathological characteristics of this tumour are described in our report.

High-grade astroblastoma in a child: Report of one case and review of literature

Background:

Astroblastoma is a rare glial neoplastic lesion that affects children and adolescents; its histogenesis remains uncertain. It is considered to account for 0.5% of all glial neoplasms, and two different subtypes have been defined based upon histologic characteristics.

Case Description:

We present the case of a 9-year-old girl who presented with headache, motor symptoms, and seizures few days before she was admitted to our institution. Computed tomography (CT) and magnetic resonance imaging (MRI) scans showed an intra-axial heterogeneous frontoparietal lesion with a striking “bubbly” appearance in MRI T2-weighted sequences and features of intracranial hypertension. Gross total resection of the tumor was achieved and the histopathologic diagnosis revealed high-grade astroblastoma. We reviewed the current published cases of astroblastoma to highlight the demographic, clinical, radiologic, and pathologic data.

Conclusion:

Astroblastomas are a distinct clinicopathologic entity, with well-described radiologic, pathologic, and cytogenetic features. Its recurrence is high and efforts must be made to elucidate the role and usefulness of radiotherapy and chemotherapy in these tumors.

Anaplastic astroblastoma: a rare glial tumour

Astroblastoma is a rarely diagnosed primary brain neoplasm whose histogenesis has been clarified recently. It occurs in children and young adults and presents as a well-circumscribed, contrast enhancing lesion in the cerebral hemisphere. Here the authors present a case of 25-year-old woman with an astroblastoma in the left frontal convexity that was excised. The characteristic radiological and histopathological features of this case are described. An astroblastoma should be included in the differential of a localised brain tumour, especially in a young patient.

Tanycytic ependymoma of the spinal cord with anaplastic cytological features

In a 43-year-old man, an intramedullary spinal cord tumor spreading from the level of the T2 to T5 vertebrae was subtotally resected. The tumor predominantly consisted of a fascicular proliferation of spindle cells having bland nuclei and bipolar, long cytoplasmic processes, and a few perivascular pseudo-rosettes were found. Although there were no true ependymal rosettes, intracytoplasmic dot-like immunoreactivity for epithelial membrane antigen (EMA) was found in a few cells. In some areas, a dense and diffuse proliferation of anaplastic, short-spindled cells having hyperchromatic nuclei and scant cytoplasm was noted, and the Ki-67 labeling index was remarkably higher (18.2%) in these areas. Neither microvascular proliferation nor necrosis was observed. In the boundary region, these two areas showed gradual transition from one to the other. The patient has remained free from recurrence for 10 months postoperatively. This is the first documentation of tanycytic ependymoma in which tumor cells showed anaplastic cytological features.

Consecutive histological changes in an astroblastoma that disseminated to the spinal cord after repeated intracranial recurrences: a case report

A 17-year-old male patient underwent surgery five times (four consecutive intracranial tumor removal surgeries and a final spinal tumor removal surgery). After the third surgery, this case was reported as a low-grade astroblastoma that is characterized by perivascular pseudorosettes consisting of elongated tumor cells arranged around the blood vessels. However, the fourth and fifth surgical specimens demonstrated very interesting histological changes in the astroblastoma. Through the course of relapses, the constituent cells of the astroblastic perivascular rosettes became smaller and rounder, and a multilayered cell arrangement was observed. The nucleus-to-cytoplasm ratio increased, and the compact intervascular cells ultimately lost glial fibrillary acidic protein (GFAP) expression. These undifferentiated cells showed high MIB-1 indices and an increased olig2 index. On the other hand, the cells in all the surgical specimens were positive for certain neuronal markers such as NSE, TUJ1, and nestin. Some astroblastomas may be more immature than the usual astrocytes; however, it is necessary to study more cases to confirm this.

Tanycytic ependymoma arising from the right lateral ventricle: a case report and review of the literature

A 38-year-old man presented with a year-long history of worsening headache. Neuroradiological findings showed that a solid cystic mass occupied the right lateral ventricle. Histologically, the tumor composed of nuclear dense zones consisting of a cluster of spindle cells and fibrillary zones consisting of streaming of cell processes. The tumor cells showed the characteristics of monopolar or bipolar processes. Some tumor cell processes extended to the vessel wall and formed ill-defined perivascular rosettes. No mitoses or necrosis were found. The cells presented positive for GFAP, S-100 protein, vimentin, Nestin and neurofilament, and dotlike positive for epithelial membrane antigen, but negative for Syn and NeuN. Four cases of tanycytic ependymoma arising from the lateral ventricle have been reported in literature. Histological differential diagnosis includes spindle-shaped neuroepithelial tumors, such as pilocytic astrocytoma, fibrillary astrocytoma and schwannoma. Tanycytic ependymoma has slightly better prognosis than other ependymoma subtypes.

Astroblastoma in a child

BACKGROUND

Astroblastoma, an uncommon neuroepithelial tumor, typically presents in young adults as a well-circumscribed cortical or subcortical spherical mass. Astroblastoma may cause a diagnostic problem to anyone unfamiliar with its architectural and histological features.

CASE HISTORY

We report the case of a 4-year-old boy who was referred for complaints of progressive deficits of balance and difficulty with walking during the previous 3 months. A large fronto-parietal cystic mass with solid mural nodule was discovered. Total removal of the tumor mass was performed, and a diagnosis of high grade (malignant) variant of astroblastoma was made. Postoperatively, the patient received radiation therapy, for a period of 11 weeks, followed by chemotherapy. He is in a good neurological recovery without any evidence of recurrence for 8 months.

PROGNOSIS

The best treatment modality for astroblastoma is surgical resection if possible, whereas adjuvant therapy (radiotherapy and/or chemotherapy) can be considered in high-grade astroblastomas, with a close follow-up for all cases.

Intraventricular astroblastoma. Case report

Astroblastoma is a rare primary brain neoplasm that accounts for 0.45-2.8% of brain gliomas. Intraventricular localization is extremely rare. The authors report a case of well-differentiated completely intraventricular astroblastoma in a 6-year-old girl and review the relevant literature. Their patient presented with a 5-week history of progressive nausea and vomiting. Magnetic resonance (MR) imaging revealed a large, well-demarcated, solid-cystic mass in the left temporooccipital ventricular horn. Macroscopic radical resection of the tumor was performed via the superior temporal sulcus. The postoperative course was uneventful and no adjuvant therapy was administered after surgery. No recurrence was detected at 9-months follow-up. Gross-total resection has the greatest impact on patient survival. In differentiated tumors, recurrence is usually local, and adjuvant therapy is recommended after repeated resection for the treatment of recurrence. In patients harboring anaplastic astroblastoma, gross-total resection and adjuvant therapy after the initial surgery seems to be the best choice. It is important to distinguish astroblastoma from ependymoma in clinical practice because of the differences in therapeutic approaches.

Brainstem astroblastoma: a case report and review of the literature

BACKGROUND

Astroblastoma is a rare glial tumor that occurs mainly in the cerebral hemispheres of young adults. Our purpose in writing this article is to report one case of astroblastoma located within the medulla and review the literature on this infrequent tumor.

METHODS

One case of astroblastoma was retrospectively reviewed. Presenting complaints, radiographic images, operative procedure, and histopathologic findings were recorded.

RESULTS

Contrast-enhanced MRI scan revealed a well-defined, well-circumscribed, contrast-enhanced cystic lesion approximately 16 mm in diameter within the medulla oblongata. Light microscopy demonstrated a papillary neoplasm composed of mildly pleomorphic cells with indistinct cytoplasmic borders. The nuclei were generally round to oval in shape. Occasional rosettes of tumor cells were seen around blood vessels. Mitoses were not seen within the submitted specimen. One small area of necrosis was present. The tumor exhibited thickened but not hyalinized blood vessel walls. The tumor cells exhibited strong staining for EMA and vimentin throughout the tissue section. Neurofilament, CAM 5.2, and CK immunostains were negative, except for rare positive staining of CK between cells and within rare tumor cells. Ki-67 was positive in small numbers of tumor nuclei, with an overall reactivity of 7%. By electron microscopy, the tumor nuclei had irregularly round to oval nuclei with moderate clumping of the chromatin, especially at the nuclear margins.

CONCLUSIONS

The combination of the radiologic and histopathologic characteristics of this tumor is necessary for making the diagnosis of astroblastoma. This article serves to summarize these characteristics as well as to report of an unusual location for this mainly hemispheric tumor.

AN ASTROBLASTOMA MIMICKING A CAVERNOUS MALFORMATION

OBJECTIVE

Astroblastomas are rare glial neoplasms that usually occur in young adults and have a predilection for the cerebral hemispheres. Patients typically present with signs of increased intracranial pressure and seizures. Imaging studies reveal circumscribed, contrast-enhancing tumors that contain both cystic and solid components with variable peritumoral edema. Hemorrhage, which suggested the presence of a vascular lesion in this patient, has not been previously described as a feature of this neoplasm.

CLINICAL PRESENTATION

The authors report the case of a 33-year-old woman who presented with spontaneous intraparenchymal hemorrhage. The collective radiographic data suggested the presence of a cavernous malformation.

INTERVENTION

A right frontotemporal craniotomy was performed under frameless stereotactic image guidance. An astroblastoma was diagnosed after resection and neuropathological examination.

CONCLUSION

A rare radiological to pathological correlation of astroblastoma is presented in which the evolving hematoma, as observed on magnetic resonance imaging scans, complicated the radiographic diagnosis of this lesion. The clinical, radiographic, and pathological features of astroblastomas, as well as the natural history of these rare glial neoplasms, are reviewed. This case illustrates the capacity of astroblastomas to hemorrhage, disguising the classic radiographic findings typical of this glial neoplasm.

Astroblastoma presenting with intracerebral hemorrhage misdiagnosed as dural arteriovenous fistula: review of a rare entity

BACKGROUND

Astroblastoma is one of the most unusual types of tumors whose histogenesis has been recently clarified. It occurs mainly among children and young adults. It is grossly well demarcated and shows histologically characteristic perivascular pseudorosettes with frequent vascular hyalinization. Immunohistochemically, the tumor cells show diffuse strong positivity for GFAP, S-100 protein, vimentin, as well as neuron-specific enolase and focal positivity for EMA.

CASE DESCRIPTION

Our patient is a 33-year-old gentleman who presented with intraparenchymal hemorrhage in the left temporal lobe. A 4-vessel cerebral angiogram revealed a dural AVF in the left posterior temporal area. The lesion was resected, and pathology showed a GFAP-positive lesion with prominent astroblastoma rosettes. There was abundant hemosiderin consistent with a prior hemorrhage. Because of its high degree of proliferation, the presence of astroblastic pseudorosettes, prominent perivascular hyalinization, regional hyaline changes, and pushing borders with regard to the adjacent brain, the tumor was considered anaplastic.

CONCLUSIONS

Astroblastoma is a rare pure pathologic entity--a distinct form of astrocytic gliomas. The diagnosis of astroblastoma is often difficult because of the astroblastic aspects that can be found in astrocytic tumors, in ependymomas, and in nonneuroepithelial tumors. The natural history seems to be between astrocytomas and glioblastomas. Total resection and radiation therapy seem to be the advisable treatments.

An astroblastoma case associated with loss of heterozygosity on chromosome 9p

The tumorigenesis of astroblastomas has not yet been elucidated on the basis of histopathological studies, and genetic studies may be useful for obtaining additional information regarding the tumorigenesis of these tumors. Here, we report an astroblastoma case in which a genetic analysis was performed. A 16-year-old female with a progressive headache was found to have a demarcated cystic tumor with a mural nodule in the right parietal lobe. Total removal of the tumor was achieved and a histological examination verified that the tumor was an astroblastoma. A genetic analysis using microsatellite markers revealed loss of heterozygosity (LOH) on chromosome 9p. The postoperative course was uneventful and, to date, she has been followed up for 2 years with no signs of recurrence. This is the first reported case of an astroblastoma in which LOH was detected on 9p. Based on this result, the tumorigenesis of astroblastomas is discussed.

Astroblastoma: immunohistochemical and ultrastructural study of distinctive epithelial and probable tanycytic differentiation

We report the clinicopathological findings of astroblastoma found in an 8-year-old girl who was subsequently treated for 11 years. The primary superficially circumscribed tumor was located in the frontoparietal lobe, while the recurrent and the second recurrent tumor were restricted to the same region 11 years later. The tumors obtained on these three occasions showed fundamentally the same histological, immunohistochemical and fine structural features. They exhibited astrocytic as well as ependymal tanycytic features with apparent epithelial cell lineage. The tumor cells showed typical features of astroblastoma comprising prominent perivascular pseudorosettes with remarkable vascular sclerosis. The immunohistochemical study revealed intensive positivity of GFAP, vimentin, epithelial membrane antigen (EMA), cytokeratin, connexin 26 and 32, desmocollin 1 and neuronal cadherin. The fine structure revealed divergent types of junctional complexes, some of which were connected with tonofilament bundles. Numerous microvilli protruded and basal lamina abutted on the tumor cell surface. We report these unique histological features, and stress that astroblastoma should be categorized as a specific type of neuroepithelial tumor.

Astroblastoma: clinicopathologic features and chromosomal abnormalities defined by comparative genomic hybridization

Astroblastomas are uncommon brain tumors whose classification and histogenesis have been debated. Precise criteria for diagnosis have been described only recently, but have not found wide acceptance. We report the clinical, radiographic, and histopathologic features of 20 astroblastomas, and the chromosomal alterations in seven cases as detected by comparative genomic hybridization (CGH). The tumors occurred both in children and young adults (average age, 14 years), most often as well circumscribed, peripheral, cerebral hemispheric masses. Radiographically, the lesions were contrast-enhancing and solid, often with a cystic component. All were characterized histologically by astroblastic pseudorosettes, and most displayed prominent perivascular hyalinization, regional hyaline changes, and pushing borders in regard to adjacent brain. Tumor cells were strongly immunoreactive for S-100 protein, GFAP, and vimentin. Staining for EMA was focal. Ten of 20 astroblastomas were classified as "well differentiated" and 10 were classified as "malignant," largely on the basis of hypercellular zones with increased mitotic indices, vascular proliferation, and necrosis with pseudopalisading. All 10 well differentiated lesions and 8 of 10 malignant lesions were completely resected. None of the well differentiated astroblastomas recurred within the limited follow-up period. Three malignant astroblastomas recurred, including two incompletely resected tumors, and one that had been totally resected. One patient died of disease following recurrence. The most frequent chromosomal alterations detected by CGH were gains of chromosome arm 20q (4/7 tumors) and chromosome 19 (3/7). The combination of these gains occurred in three, including two well differentiated and one malignant astroblastoma. Other alterations noted in two tumors each were losses on 9q, 10, and X. These chromosomal alterations are not typical of ependymoma or infiltrating astrocytic neoplasms, and suggest that astroblastomas may have a characteristic cytogenetic profile in addition to their distinctive clinical, radiographic, and histopathologic features.

Complete surgical resection of high-grade astroblastoma with long time survival: case report and review of the literature

Astroblastoma is a rare glial neoplasm of unknown origin and uncertain prognosis. It usually presents in young adults as a well circumscribed hemispheric mass, often associated with a cystic component. The histological features of astroblastoma are the presence of typical astroblastic perivascular pseudorosettes and perivascular hyalinization. Two different subtypes of astroblastoma have been defined based upon histological characteristics. Prognosis, however, sometimes is in contradiction with the pathological appearance and seems to be more closely related to the grade of surgical resection. We present a new case of a patient with a high-grade astroblastoma with a long survival time, in whom complete surgical resection was confirmed by an early postoperative MRI.

Monomorphous Angiocentric Glioma: A Distinctive Epileptogenic Neoplasm With Features of Infiltrating Astrocytoma and Ependymoma

We present 8 examples of a neoplasm with features of both astrocytoma and ependymoma that may represent a distinct clinicopathologic entity. The cerebral hemispheric tumors occurred in patients that were 3, 4, 12, 14, 15, 26, 30, and 37 years of age. All presented with seizures that, with the exception of 2, began in childhood. Magnetic resonance imaging studies showed ill-defined, T2-hyperintense, generally noncontrast-enhancing lesions that, although centered on the cortex or amygdala, extended into the underlying white matter for a short distance. Histologically, the variably infiltrative tumors were distinctively angiocentric with well-developed perivascular pseudorosettes in some cases. Longitudinal and/or circumferential orientations of perivascular cells were common also. The cells were uniform in their cytologic features from case to case and were bipolar in all but one case. A glial nature was inferred from immunoreactivity for GFAP, and ependymal differentiation was suggested by positivity for EMA in three cases and ultrastructural features in one. Overall, the tumors were biologically indolent except for one that recurred and ultimately proved fatal.

Lucien J. Rubinstein: enduring contributions to neuro-oncology

Dr. Lucien Rubinstein is best remembered for his significant contributions to the field of neuropathology, particularly in the classification of nervous system tumors. His accomplishments in basic neuro-oncology and in the formulation of diagnostic principles reflected a unique talent for synthesizing fundamental clinicopathological concepts based on skillful diagnostic investigation and a thorough understanding of neurobiology. Dr. Rubinstein was the leader in the establishment of cell cultures from central nervous system (CNS) tumors. He meticulously analyzed both light and electron microscopic features of CNS tumors, recorded his findings, and patiently drew sketches to be shared generously with his colleagues and students. As a pioneer in neuropathology, in his work Dr. Rubinstein set the foundation for many enduring concepts in neurosurgery, neuro-oncology, neurology, and basic tumor biology.

Astroblastoma in childhood: pathological and clinical analysis

OBJECT

The object was to describe the clinical, radiologic, and pathologic features of astroblastomas in an unselected group of children who were treated in a single institution during an 11-year period.

METHODS

Eight children with astroblastomas of the brain were examined. Diagnosis was based on cell morphology, vascular attachment of the cell main process, lack of an epithelial-free surface differentiation, and poor intercellular cohesiveness. In addition to sections, tumor smears and electron microscopy were required for demonstrating or confirming such features.

CONCLUSIONS

Clinical findings seem to confirm an apparent predilection of astroblastomas for younger children (median age of onset, 5 years) and the existence of two prognostically different types of tumor-well differentiated (low grade) and anaplastic (high grade). Microscopic findings suggest a closer resemblance of tumor cells to astroblasts rather than to "tanycytes" or ependymal cells. It seems, however, that anaplastic astroblasts have a tendency to evolve toward, or be associated with, less differentiated cells, either neuroepithelial or sarcomatous.

Expression of aquaporin water channels in mouse spinal cord

Aquaporins (AQPs) are membrane proteins involved in water transport in many fluid-transporting tissues. Aquaporins AQP1, AQP4, and AQP9 have been identified in brain and hypothesized to participate in brain water homeostasis. Here we use reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry to describe the expression and immunolocalization of AQPs in adult mouse spinal cord. AQP4 was expressed in glial cells, predominantly in gray matter, and in astrocytic end-feet surrounding capillaries in spinal cord white matter. AQP9 expression extensively co-localized with glial fibrillary acidic protein-immunoreactive astrocytes, located predominantly in the white matter. AQP5 was detected by RT-PCR but not by immunohistochemical analysis. Interestingly, AQP8 was detected primarily in ependymal cells lining the fluid-filled central canal. The aquaporin expression pattern in spinal cord suggests involvement in water homeostasis and diseases associated with abnormal water fluxes such as spinal cord injury and syringomyelia.

Possible Oncogenicity of Subventricular Zone Neural Stem Cells: Case Report

OBJECTIVE

The origin of brain tumors has attracted much controversy. Recent advances in neural stem cell biology coupled with the new concepts of central nervous system development have raised interesting possibilities regarding the oncogenic properties of neural stem/progenitor cells. To elucidate these putative properties further, the clinical materials from an infant brain tumor were analyzed, focusing on the relation with the neural stem/progenitor cells.

METHODS

The expression of neural stem/progenitor cell markers in the tumor cells and the cellular components of the infant brain tumor were examined using immunohistochemistry. The tumor cell biology was analyzed both in culture and in the grafted brain environment.

RESULTS

Three main bodies of evidence were demonstrated indicating that the tumor was of possible subventricular zone postnatal or adult normal neural stem cell origin. First, in the tumor specimen we demonstrated the strong positive expression of the neural stem/progenitor cell markers, nestin and Musashi-1. Second, immunohistochemistry revealed the presence of neuronal, astrocytic, and immature precursor cells in the tumor tissue, similar to the cellular components of the subventricular zone, thereby pointing to the subventricular zone as the possible origin of the tumor. The subventricular zone also is one of the strong candidates for the location of postnatal/adult neural stem cells. This cellular evidence was strengthened further by the clinicoradiological findings that demonstrated the involvement of the subventricular zone of the lateral ventricle by the tumor. Third, in the in vitro and in vivo experiments, a dynamic shift in expression patterns between neural stem cells (nestin, Musashi-1) and differentiated cells (glial fibrillary acidic protein, neuron-specific Class III beta-tubulin) markers was seen, similar to the proposed behavior of postnatal/adult neural stem cells in situ.

CONCLUSION

These findings suggest that this brain tumor originated from neural stem cells located in the subventricular zone, and the further possibility of the general oncogenic potential of neural stem cells.

Astroblastoma: a case report

Astroblastoma is one of the very unusual type of tumors, whose histogenesis has not been clarified. It occurs mainly among children or young adults. Astroblastoma is grossly well-demarcated, and shows histologically characteristic perivascular pseudorosettes with frequent vascular hyalinization. Perivascular pseudorosettes in astroblastoma have short and thick cytoplasmic processes and blunt-ended foot plates. A 15-yr-old girl presented with headache and diplopia for one and a half year. A well-demarcated mass, 9.7 cm in diameter, was found in the right frontal lobe in brain MRI, and it was a well-enhanced inhomogenous mass. Cystic changes of various sizes were observed inside the tumor mass as well as in the posterior part of the mass, but no peritumoral edema was found. Histologically, this mass belongs to a typical astroblastoma, and no sign of anaplastic astrocytoma, gemistocytic astrocytoma or glioblastoma was found in any part of the tumor. Immunohistochemically, the tumor cells showed diffuse strong positivity for glial fibrillary acidic protein, S-100 protein, vimentin and neuron specific enolase, and focal positivity for epithelial membrane antigen and CAM 5.2, while showing negativity for synaptophysin, neurofilament protein, pan-cytokeratin and high molecular weight keratin.