The high mitotic count detected by phospho-histone H3 immunostain does not alter the benign behavior of angiocentric glioma

Neuroimaging features of angiocentric glioma: A case series and systematic review

BACKGROUND AND PURPOSE

Angiocentric gliomas (AGs) are epileptogenic low-grade gliomas in young patients. We aimed to investigate the MRI findings of AGs and systematically review previous publications and three new cases.

METHODS

We searched PubMed, Elsevier's abstract and citation database, and Embase databases and included 50 patients with pathologically proven AGs with analyzable preoperative MRI including 3 patients from our institution and 47 patients from 38 publications (median age, 13 years [range, 2-83 years]; 35 men). Two board-certified radiologists reviewed all images. The relationships between seizure/epilepsy history and MRI findings were statistically analyzed. Moreover, clinical and imaging differences were evaluated between supratentorial and brainstem AGs.

RESULTS

Intratumoral T1-weighted high-intensity areas, stalk-like signs, and regional brain parenchymal atrophy were observed in 23 out of 50 (46.0%), 10 out of 50 (20.0%), and 14 out of 50 (28.0%) patients, respectively. Intratumoral T1-weighted high-intensity areas were observed significantly more frequently in patients with stalk-like signs (positive, 9/10 vs. negative, 14/40, p = .0031) and regional atrophy (13/14 vs. 10/36, p = .0001). There were significant relationships between the length of seizure/epilepsy history and presence of intratumoral T1-weighted high-intensity area (median 3 years vs. 0.5 years, p = .0021), stalk-like sign (13.5 vs. 1 year, p < .0001), and regional atrophy (14 vs. 0.5 years, p < .0001). Patients with brainstem AGs (n = 7) did not have a seizure/epilepsy history and were significantly younger than those with supratentorial AGs (median, 5 vs. 13 years, p < .0001, respectively).

CONCLUSIONS

Intratumoral T1-weighted high-intensity areas, stalk-like signs, and regional brain atrophy were frequent imaging features in AG. We also found that affected age was different between supratentorial and brainstem AGs.

Clinical characteristics, treatment and prognosis of angiocentric glioma

Angiocentric glioma (AG) is a rare subtype of neuroepithelial tumor in children and young adults that commonly presents with seizures. To study the clinical characteristics, treatment and prognosis of patients with AG, the features of two cases of AG were described and 108 cases reported in the literature were assessed. The cases of the present study were two males aged 8 and 16 years, who mainly presented with seizures. MRI revealed superficial, non-enhanced lesions in the left temporal and right frontal lobe, respectively. The two patients underwent gross total resection (GTR) and remained seizure-free without neurological deficits after 3.5 and 2.5 years, respectively. Histopathological examination revealed that the tumors consisted of monomorphous cells that surrounded the blood vessels and neurons in the cerebral cortex, and formed concentric sleeves or pseudorosettes. Furthermore, immunostaining indicated that the diffuse infiltrative neoplastic cells were positive for glial fibrillary acidic protein and a dot-like pattern of epithelial membrane antigen was observed. AG mostly appeared similar to low-grade gliomas on MRI. GTR of the lesions was curative and radiation or chemotherapy were not required. AG typically has a favorable prognosis, with low mortality and incidence of disability.

Histologic classification of gliomas

Gliomas form a heterogeneous group of tumors of the central nervous system (CNS) and are traditionally classified based on histologic type and malignancy grade. Most gliomas, the diffuse gliomas, show extensive infiltration in the CNS parenchyma. Diffuse gliomas can be further typed as astrocytic, oligodendroglial, or rare mixed oligodendroglial-astrocytic of World Health Organization (WHO) grade II (low grade), III (anaplastic), or IV (glioblastoma). Other gliomas generally have a more circumscribed growth pattern, with pilocytic astrocytomas (WHO grade I) and ependymal tumors (WHO grade I, II, or III) as the most frequent representatives. This chapter provides an overview of the histology of all glial neoplasms listed in the WHO 2016 classification, including the less frequent "nondiffuse" gliomas and mixed neuronal-glial tumors. For multiple decades the histologic diagnosis of these tumors formed a useful basis for assessment of prognosis and therapeutic management. However, it is now fully clear that information on the molecular underpinnings often allows for a more robust classification of (glial) neoplasms. Indeed, in the WHO 2016 classification, histologic and molecular findings are integrated in the definition of several gliomas. As such, this chapter and Chapter 6 are highly interrelated and neither should be considered in isolation.

Angiocentric glioma transformed into anaplastic ependymoma: Review of the evidence for malignant potential

Angiocentric glioma (AG) is a low grade glioma, that was first described in 2002. Since this description, 83 patients with AG have been described, including ours. AG typically presents in childhood with medically refractory seizures that are cured with gross surgical resection. Whilst the natural history is that of a benign tumour, there have been reports of recurrence, transformation, and malignant features that suggest that AG is potentially malignant. We add to the literature a case of a 16-year-old girl who presented in May 2011 with a 3-month history of complex partial seizures, with MRI showing a T2-weighted hyperintense lesion in the left insula and inferior frontal lobe. This was confirmed on biopsy as AG and was followed with surveillance imaging. In April 2012, she presented with disease progression and underwent a left temporal lobectomy, with histology showing both AG and grade II astrocytoma. Adjuvant radiotherapy of 50 Gray in 28 fractions was administered. A small area of contrast enhancement appeared in the left parietal lobe in December 2012, which progressed over subsequent months. In June 2013, she underwent a near total excision, with histology showing anaplastic ependymoma. She received six cycles of adjuvant temozolamide. Despite this, the tumour continued to progress, with her seizure control deteriorating, and the development of a right hemiparesis. The patient died in January 2014, aged 19years.

Clinical attributes and surgical outcomes of angiocentric gliomas

Angiocentric gliomas (AG) are exceedingly rare low-grade neoplasms which often present in the form of intractable epilepsy within younger patients. The current study extensively reviews all reported cases which were pathologically verified as AG in the literature to analyze clinical attributes and surgical outcomes of this neoplasm. There were 88 patients with AG reported in the literature consisting mostly of pediatric cases. The sex distribution consisted of 45 males and 36 females with the remaining seven cases not documenting sex. The average age of initial diagnosis was 16years with almost half of all diagnosed patients being within the first decade of life. In cases where extent of resection was reported, gross total resection (GTR) was achieved in 54 patients, subtotal resection (STR) in 16, and biopsy only in three. Post-operative complications were transient and only occurred in three patients with no reports of death following surgery. Only five cases reported tumor recurrence on follow-up. Eight patients had seizure recurrence post-operatively and GTR offered improved rates of seizure control when compared to STR (p=0.0005). Nearly half of the cases of AG are diagnosed within the first decade of life and they usually manifest with intractable seizures. GTR appears to offer better seizure control in the post-operative period. Surgical resection is the mainstay therapy for AG as post-operative complications and tumor recurrence remain uncommon. Since the number of reported cases is limited, future studies with longer follow-up periods will help elaborate more long-term outcomes.

Rare glial tumors

This chapter describes the epidemiology, pathology, molecular characteristics, clinical and neuroimaging features, treatment, outcome, and prognostic factors of the rare glial tumors. This category includes subependymal giant cell astrocytoma, pleomorphic xanthoastrocytoma, astroblastoma, chordoid glioma of the third ventricle, angiocentric glioma, ganglioglioma, desmoplastic infantile astrocytoma and ganglioma, dysembryoplastic neuroepithelial tumor, papillary glioneuronal tumor, and rosette-forming glioneuronal tumor of the fourth ventricle. Many of these tumors, in particular glioneuronal tumors, prevail in children and young adults, are characterized by pharmacoresistant seizures, and have an indolent course, and long survival following surgical resection. Radiotherapy and chemotherapy are reserved for recurrent and/or aggressive forms. New molecular alterations are increasingly recognized.

Cystoid angiocentric glioma: A case report and literature review

Angiocentric glioma is a rare subtype of neuroepithelial tumor that is associated with a history of epilepsy. We report a case of cystoid angiocentric glioma associated with an area of calcification. This 25 year old male patient presented with tonic clonic spasm. He underwent craniotomy with complete resection of the lesion. Pathologic specimen showed monomorphous bipolar cells with angiocentric growth pattern.

Intractable epilepsy due to angiocentric glioma: A case report and minireview

The aim of this case report and minireview was to investigate the diagnosis of and therapeutic approaches for angiocentric glioma (AG) and to summarize the clinical manifestations and the pathological and imaging characteristics of the disease. Intraoperative cortical electroencephalogram (ECoG) monitoring was performed to locate the epileptic foci in a child with AG who presented with intractable epilepsy, prior to the total resection of the tumor being performed under the microscope. The clinical features, imaging characteristics, intraoperative conditions, surgical methods and pathological results were analyzed and compared with the literature. The review revealed that to date, the clinical features of the 52 reported cases of AG (including this case) have been mainly characterized by epilepsy. High T2-weighted image (WI) and fluid-attenuated inversion recovery (FLAIR) signals may be detected with magnetic resonance imaging (MRI) scanning of the cranium; however, no enhancement signals are detected by enhanced scanning. The prognosis following surgical resection is favorable. The lesions in the present case demonstrated clear boundaries with a central cystic affection accompanied by an arachnoid cyst on the left temporal pole. Pathological examination revealed that the lesion was positive for glial fibrillary acidic protein (GFAP), S-100 protein, vimentin, epithelial membrane antigen (EMA), cluster of differentiation 99 (CD99) and D2-40. The Ki-67/MIBk-1 labeling index was ~1%. In conclusion, AG exhibits characteristic features in imaging; however, its diagnosis depends on histopathological examination. The prognosis of total surgical resection is good and intraoperative ECoG may be used to assist positioning.

Imaging characteristics of an unusual, high-grade angiocentric glioma: a case report and review of the literature

Angiocentric gliomas have recently been reclassified as a separate central nervous system tumor. Few cases have been reported, and most of those correspond to slow-growing, low-grade neoplasms in very young pediatric patients. Here we describe magnetic resonance imaging findings (including diffusion imaging, spectroscopy and tractography) in an unusual higher-grade neoplasm with pathologic features suggestive of an angiocentric glioma in a 15-year-old male. The tumor had mild heterogeneous enhancement on magnetic resonance imaging, and a low apparent diffusion coefficient (9.9 × 10(-4) mm(2)s(-1)), consistent with an intermediate-to-high cellularity tumor. Spectroscopic imaging showed elevated choline/phosphocreatine and choline/N-acetyl aspartate ratios, suggesting an unusually aggressive tumor. We conclude that angiocentric glioma should not be excluded from consideration at primary diagnosis, particularly in teenaged patients nearing adulthood.

Long-term epilepsy-associated tumors

The term long-term epilepsy associated tumor (LEAT) encompasses lesions identified in patients investigated for long histories (often 2 years or more) of drug-resistant epilepsy. They are generally slowly growing, low grade, cortically based tumors, more often arising in younger age groups and in many cases exhibit neuronal in addition to glial differentiation. Gangliogliomas and dysembryoplastic neuroepithelial tumors predominate in this group. LEATs are further united by cyto-architectural changes that may be present in the adjacent cortex which have some similarities to developmental focal cortical dysplasias (FCD); these are now grouped as FCD type IIIb in the updated International League Against Epilepsy (ILAE) classification. In the majority of cases, surgical treatments are beneficial from both perspectives of managing the seizures and the tumor. However, in a minority, seizures may recur, tumors may show regrowth or recurrence, and rarely undergo anaplastic progression. Predicting and identifying tumors likely to behave less favorably are key objectives of the neuropathologist. With immunohistochemistry and modern molecular pathology, it is becoming increasingly possible to refine diagnostic groups. Despite this, some LEATs remain difficult to classify, particularly tumors with "non-specific" or diffuse growth patterns. Modification of LEAT classification is inevitable with the goal of unifying terminological criteria applied between centers for accurate clinico-pathological-molecular correlative data to emerge. Finally, establishing the epileptogenic components of LEAT, either within the lesion or perilesional cortex, will elucidate the cellular mechanisms of epileptogenesis, which in turn will guide optimal surgical management of these lesions.

Functional role of laminin α1 chain during cerebellum development

We had developed a conditional Laminin α 1 knockout-mouse model (Lama1(cko)) bypassing embryonic lethality of Lama1 deficient mice to study the role of this crucial laminin chain during late developmental phases and organogenesis. Here, we report a strong defect in the organization of the adult cerebellum of Lama1(cko) mice. Our study of the postnatal cerebellum of Lama1(cko) animals revealed a disrupted basement membrane correlated to an unexpected excessive proliferation of granule cell precursors in the external granular layer (EGL). This was counteracted by a massive cell death occurring between the postnatal day 7 (P7) and day 20 (P20) resulting in a net balance of less cells and a smaller cerebellum. Our data show that the absence of Lama1 has an impact on the Bergmann glia scaffold that aberrantly develops. This phenotype is presumably responsible for the observed misplacing of granule cells that may explain the overall perturbation of the layering of the cerebellum and an aberrant folia formation.