Pleomorphic xanthoastrocytoma

Pediatric-Like Brain Tumors in Adults

Pediatric brain tumors are different to those found in adults in pathological type, anatomical site, molecular signature, and probable tumor drivers. Although these tumors usually occur in childhood, they also rarely present in adult patients, either as a de novo diagnosis or as a delayed recurrence of a pediatric tumor in the setting of a patient that has transitioned into adult services.Due to the rarity of pediatric-like tumors in adults, the literature on these tumor types in adults is often limited to small case series, and treatment decisions are often based on the management plans taken from pediatric studies. However, the biology of these tumors is often different from the same tumors found in children. Likewise, adult patients are often unable to tolerate the side effects of the aggressive treatments used in children-for which there is little or no evidence of efficacy in adults. In this chapter, we review the literature and summarize the clinical, pathological, molecular profile, and response to treatment for the following pediatric tumor types-medulloblastoma, ependymoma, craniopharyngioma, pilocytic astrocytoma, subependymal giant cell astrocytoma, germ cell tumors, choroid plexus tumors, midline glioma, and pleomorphic xanthoastrocytoma-with emphasis on the differences to the adult population.

Diagnostic Insights into Pediatric Pleomorphic Xanthoastrocytoma through DNA Methylation Class and Pathological Diagnosis Analysis

This study adopts an innovative approach to utilize the DNA methylation class (MC) by prioritizing the understanding of discrepancies over traditional direct comparisons with the pathological diagnosis (PD). The aim is to clarify the morphological criteria for pleomorphic xanthoastrocytoma (PXA). Using the Children's Brain Tumor Network online database, PXA-diagnosed cases were sourced. MCs and CDKN2A/B statuses were ascertained using the Heidelberg methylation brain tumor classifier v12.5 (v12.8 for selected cases). Three distinct groups emerged: Group 1 confirmed PXA through both PD and MC (7 cases); Group 2 identified PXA via PD alone (7 cases); and Group 3 diagnosed PXA using MC (5 cases). Key insights from the study include the frequent local infiltration of PXA into gray matter structures, mirroring infiltrative astrocytoma. The MC for PXA stands out for its sensitivity. Cases with a PXA morphological diagnosis diverging from the DNA class warrant attention to newer differential diagnoses such as high-grade astrocytoma with piloid features, pilocytic astrocytoma NF1-associated, and NET-PATZ1. Tumors with a MC indicative of PXA but lacking its typical features may, if high-grade, behave as grade 4 gliomas. In contrast, their low-grade counterparts could belong to the PXA morphological continuum. Further research is pivotal for cementing these findings.

Clinical features and surgical outcomes of high grade pleomorphic xanthoastrocytomas: a single-center experience with a systematic review

Purpose

High grade pleomorphic xanthoastrocytomas (HGPXAs) are very rare and their management and prognostic outcomes remain unclear. To better understand the disease, we aimed to evaluate the risk factors for progression-free survival (PFS) and overall survival (OS), and propose a treatment protocol based on cases from our institute and cases from the literature.

Methods

The authors reviewed the clinical data of 26 patients with HGPXAs who underwent surgical treatment in Department of Neurosurgery of Beijing Tiantan Hospital between August 2014 and September 2021. We also searched the PubMed database using the keywords "anaplastic" combined with "pleomorphic xanthoastrocytoma(s)" between January 1997 and October 2022. Risk factors for PFS and OS were evaluated in the pooled cases.

Results

The authors' cohort included 11 males and 15 females with a mean age of 36.7 ± 20.3 years (range: 5.5-71 years). Gross-total resection (GTR) and non-GTR were achieved in 17 (65.4%) and 9 (34.6%) patients, respectively. Radiotherapy and chemotherapy were administered to 22 and 20 patients, respectively. After a mean follow-up of 20.5 ± 21.2 months (range: 0.5-78.1 months), 7 patients suffered tumor recurrence and 6 patients died with a mean OS time of 19.4 ± 10.8 months (range: 8-36 months). In the literature between January 1997 and October 2022, 56 cases of HGPXAs were identified in 29 males and 27 females with a mean age of 29.6 ± 19.6 years (range; 4-74 years). Among them, 24 (44.4%) patients achieved GTR. Radiotherapy and chemotherapy was administered to 31 (62%) patients and 23 (46%) patients, respectively. After a median follow-up of 31.4 ± 35.3 months (range: 0.75-144 months), the mortality and recurrence rates were 32.5% (13/40) and 70% (28/40), respectively. Multivariate Cox regression model demonstrated that non-GTR (HR 0.380, 95% CI 0.174-0.831, p=0.015), age≥30 (HR 2.620, 95% CI 1.183-5.804, p=0.018), no RT (HR 0.334,95% CI 0.150-0.744, p=0.007) and no CT (HR 0.422, 95% CI 0.184-0.967, p=0.042) were negative prognostic factors for PFS. Non-GTR (HR 0.126, 95% CI 0.037-0.422, p=0.001), secondary HGPXAs (HR 7.567, 95% CI 2.221-25.781, p=0.001), age≥30 (HR 3.568, 95% CI 1.190-10.694, p=0.023) and no RT (HR 0.223,95% CI 0.073-0.681, p=0.008) were risk factors for OS.

Conclusion

High grade pleomorphic xanthoastrocytomas are very rare brain tumors. Children and younger adults have better clinical outcome than elderly patients. Secondary HGPXAs had worse OS than primary HGPXAs. Complete surgical excision plus RT and CT is recommended for this entity. The frequency of BRAF mutations in HGPXAs is 47.5% (19/40) in this study, however, we do not find the connections between BRAF mutations and clinical outcomes. Future studies with larger cohorts are necessary to verify our findings.

Establishment and characterization of patient-derived xenograft of a rare pediatric anaplastic pleomorphic xanthoastrocytoma (PXA) bearing a CDC42SE2-BRAF fusion

Pleomorphic xanthoastrocytoma (PXA) is a rare subset of primary pediatric glioma with 70% 5-year disease free survival. However, up to 20% of cases present with local recurrence and malignant transformation into more aggressive type anaplastic PXA (AXPA) or glioblastoma. The understanding of disease etiology and mechanisms driving PXA and APXA are limited, and there is no standard of care. Therefore, development of relevant preclinical models to investigate molecular underpinnings of disease and to guide novel therapeutic approaches are of interest. Here, for the first time we established, and characterized a patient-derived xenograft (PDX) from a leptomeningeal spread of a patient with recurrent APXA bearing a novel CDC42SE2-BRAF fusion. An integrated -omics analysis was conducted to assess model fidelity of the genomic, transcriptomic, and proteomic/phosphoproteomic landscapes. A stable xenoline was derived directly from the patient recurrent tumor and maintained in 2D and 3D culture systems. Conserved histology features between the PDX and matched APXA specimen were maintained through serial passages. Whole exome sequencing (WES) demonstrated a high degree of conservation in the genomic landscape between PDX and matched human tumor, including small variants (Pearson's r = 0.794-0.839) and tumor mutational burden (~ 3 mutations/MB). Large chromosomal variations including chromosomal gains and losses were preserved in PDX. Notably, chromosomal gain in chromosomes 4-9, 17 and 18 and loss in the short arm of chromosome 9 associated with homozygous 9p21.3 deletion involving CDKN2A/B locus were identified in both patient tumor and PDX sample. Moreover, chromosomal rearrangement involving 7q34 fusion; CDC42SE-BRAF t (5;7) (q31.1, q34) (5:130,721,239, 7:140,482,820) was identified in the PDX tumor, xenoline and matched human tumor. Transcriptomic profile of the patient's tumor was retained in PDX (Pearson r = 0.88) and in xenoline (Pearson r = 0.63) as well as preservation of enriched signaling pathways (FDR Adjusted P < 0.05) including MAPK, EGFR and PI3K/AKT pathways. The multi-omics data of (WES, transcriptome, and reverse phase protein array (RPPA) was integrated to deduce potential actionable pathways for treatment (FDR < 0.05) including KEGG01521, KEGG05202, and KEGG05200. Both xenoline and PDX were resistant to the MEK inhibitors trametinib or mirdametinib at clinically relevant doses, recapitulating the patient's resistance to such treatment in the clinic. This set of APXA models will serve as a preclinical resource for developing novel therapeutic regimens for rare anaplastic PXAs and pediatric high-grade gliomas bearing BRAF fusions.

Pathomorphological Diagnostic Criteria for Focal Cortical Dysplasias and Other Common Epileptogenic Lesions—Review of the Literature

Focal cortical dysplasia (FCD) represents a heterogeneous group of morphological changes in the brain tissue that can predispose the development of pharmacoresistant epilepsy (recurring, unprovoked seizures which cannot be managed with medications). This group of neurological disorders affects not only the cerebral cortex but also the subjacent white matter. This work reviews the literature describing the morphological substrate of pharmacoresistant epilepsy. All illustrations presented in this study are obtained from brain biopsies from refractory epilepsy patients investigated by the authors. Regarding classification, there are three main FCD types, all of which involve cortical dyslamination. The 2022 revision of the International League Against Epilepsy (ILAE) FCD classification includes new histologically defined pathological entities: mild malformation of cortical development (mMCD), mild malformation of cortical development with oligodendroglial hyperplasia in frontal lobe epilepsy (MOGHE), and “no FCD on histopathology”. Although the pathomorphological characteristics of the various forms of focal cortical dysplasias are well known, their aetiologic and pathogenetic features remain elusive. The identification of genetic variants in FCD opens an avenue for novel treatment strategies, which are of particular utility in cases where total resection of the epileptogenic area is impossible.

Clinical, Morphological, and Molecular Study on Grade 2 and 3 Pleomorphic Xanthoastrocytoma

PURPOSE

Pleomorphic xanthoastrocytoma (PXA) is an uncommon astrocytoma that tends to occur in children and young adults and has a relatively favorable prognosis. The 2021 WHO classification of tumors of the central nervous system (CNS WHO), 5th edition, rates PXAs as grade 2 and grade 3. The histological grading was based on mitotic activity (≥2.5 mitoses/mm²). This study specifically evaluates the clinical, morphological, and, especially, the molecular characteristics of grade 2 and 3 PXAs.

METHODS

Between 2003 and 2021, we characterized 53 tumors with histologically defined grade 2 PXA (n = 36, 68%) and grade 3 PXA (n = 17, 32%).

RESULTS

Compared with grade 2 PXA, grade 3 PXA has a deeper location and no superiority in the temporal lobe and is more likely to be accompanied by peritumoral edema. In histomorphology, epithelioid cells and necrosis were more likely to occur in grade 3 PXA. Molecular analysis found that the TERT promoter mutation was more prevalent in grade 3 PXA than in grade 2 PXA (35% vs. 3%; p = 0.0005) and all mutation sites were C228T. The cases without BRAF V600E mutation or with necrosis in grade 3 PXA had a poor prognosis (p = 0.01).

CONCLUSION

These data define PXA as a heterogeneous astrocytoma. Grade 2 and grade 3 PXAs have different clinical and histological characteristics as well as distinct molecular profiles. TERT promoter mutations may be a significant genetic event associated with anaplastic progression. Necrosis and BRAF V600E mutation play an important role in the prognosis of grade 3 PXA.

Clinical outcomes for pleomorphic xanthoastrocytoma patients: an institutional experience

Purpose

Report our institutional experience with pleomorphic xanthoastrocytoma (PXA) to contribute to limited data on optimal management.

Methods

Patients with pathologically confirmed PXA treated at our institution between 1990 and 2019 were identified. Demographic information, tumor grade, treatment variables, and clinical outcomes were collected from patient charts. Kaplan-Meier estimates were used to summarize two primary outcome measurements: progression-free survival (PFS) and overall survival (OS). Outcomes were stratified by tumor grade and extent of resection. Cox regression and log-rank testing were performed.

Results

We identified 17 patients with pathologically confirmed PXA. Two patients were excluded due to incomplete treatment information or < 6m of follow-up; 15 patients were analyzed (median follow-up 4.4y). Six patients had grade 2 PXA and 9 had grade 3 anaplastic PXA. The 2-year and 5-year PFS for the cohort was 57% and 33%, respectively; 2-year and 5-year OS was 93% and 75%, respectively. Patients with grade 2 tumors exhibited superior PFS compared to those with grade 3 tumors (2-year PFS: 100% vs. 28%, 5-year PFS: 60% vs. 14%), hazard ratio, 5.09 (95% CI:1.06-24.50), p = 0.02. Undergoing a GTR also yielded improved outcomes (hazard ratio: 0.38, p = 0.15). All but one (89%) of the grade 3 patients underwent RT.

Conclusion

The poor survival of the cohort, especially with grade 3 tumors, suggests the need for more aggressive treatment, including maximal resection followed by intensive adjuvant therapy. Better prognostics of tumor recurrence are needed to guide the use of adjuvant therapy.

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Brain and Spinal Cord Tumors Among the Life-Threatening Health Problems: An Introduction

As one of the global concerns, cancers, including brain and spinal cord tumors, are responsible for mortalities and irreversible morbidities in the affected patients. Although advancements in molecular pathology and imaging of tumors may have influenced the incidence rate due to higher diagnosis in early stages, exposure to environmental risk factors could be another explanation for increased incidence of these tumors over the past decades. Similar to many other tumors, the CNS tumors begin in cellular dimension with activation of different molecular pathways. Several genetic, epigenetic, and immunologic pathways and processes are already discovered to play roles in pathophysiology of these tumors, which mostly will eventually become symptomatic. Each of these tumors may exhibit imaging characteristics, making it possible to list a series of differential diagnosis before histopathologic examination. Advances in molecular pathology have resulted in better understanding and categorization of CNS tumors, leading to better decision-making on the most appropriate therapeutic approach for each category, as well as proposing new therapeutic modalities to treat these tumors. As an introduction to the 2-volume book, this chapter addressed different types of human brain and spinal cord tumors based on the fifth version of WHO classification of CNS tumors.

Altered Extracellular Matrix as an Alternative Risk Factor for Epileptogenicity in Brain Tumors

Seizures are one of the most common symptoms of brain tumors. The incidence of seizures differs among brain tumor type, grade, location and size, but paediatric-type diffuse low-grade gliomas/glioneuronal tumors are often highly epileptogenic. The extracellular matrix (ECM) is known to play a role in epileptogenesis and tumorigenesis because it is involved in the (re)modelling of neuronal connections and cell-cell signaling. In this review, we discuss the epileptogenicity of brain tumors with a focus on tumor type, location, genetics and the role of the extracellular matrix. In addition to functional problems, epileptogenic tumors can lead to increased morbidity and mortality, stigmatization and life-long care. The health advantages can be major if the epileptogenic properties of brain tumors are better understood. Surgical resection is the most common treatment of epilepsy-associated tumors, but post-surgery seizure-freedom is not always achieved. Therefore, we also discuss potential novel therapies aiming to restore ECM function.

Pleomorphic Xanthoastrocytoma: a single institution retrospective analysis and a review of the literature

Background

 Pleomorphic xanthoastrocytoma (PXA) is a rare low-grade brain tumor. To date, limited studies have analyzed factors affecting survival outcomes and defined the therapeutic strategy. The aim of this retrospective analysis was to investigate the clinicopathologic characteristics of PXA and identify factors associated with outcomes.

Methods

 We retrospectively analyzed a cohort of 16 adult and children patients with PXA who underwent primary resection from 1997 to 2019, referred to our Radiation Oncology Unit and to Meyer’s Paediatric Hospital. We also reviewed the relevant literature.

Results

 All patients underwent primary surgical resection; 10 patients received adjuvant radiation treatment course, ranging from DTF 54 to 64 Gy; 8 of them received, in addition, concurrent adjuvant chemotherapy; 6 patients underwent only radiological follow-up. After a median follow up was 60 months: median OS was 34.9 months (95% CI 30–218), 1-year OS 87%, 5-years OS 50%, 10-years OS 50%; median PFS 24.4 months (95% CI 13–156), 1-year PFS 80%, 5-years PFS 33%, 10-years PFS 33%. A chi-square test showed a significant association between OS and recurrent disease (p = 0.002) and with chemotherapy adjuvant treatment (p = 0.049). A borderline statistical significant association was instead recognized with BRAF mutation (p = 0.058).

Conclusions

Despite our analysis did not reveal a strong prognostic or predictive factor able to address pleomorphic xanthoastrocytoma management; however, in selected patients could be considered the addition of adjuvant radiation chemotherapy treatment after adequate neurosurgical primary resection. Furthermore, recurrent disease evidenced a detrimental impact on survival.

The evolution of pleomorphic xanthoastrocytoma: from genesis to molecular alterations and mimics

Pleomorphic xanthoastrocytomas (PXAs) are rare tumors accounting for less than 1% of astrocytomas. They commonly occur in young patients and have relatively favorable prognosis. However, they are well known to have heterogenous morphology and biological behavior with the potential to recur and disseminate throughout the central nervous system, especially their anaplastic counterparts. Recent advances in the molecular characterization have discovered BRAFp.V600E mutations in conjunction with CDKN2A/B deletions and TERTp mutations to be the most frequent alterations in PXAs. These tumors can present a diagnostic challenge as they share overlapping histopathological, genomic as well as methylation profile with various other tumor types, particularly epithelioid glioblastomas (eGBs). This review provides the spectrum of evolution of PXAs from their genesis to recent molecular insights and attempts to review pathogenesis and relationship to other tumors that they mimic especially eGB. It is postulated based on evidence from literature that PXA and eGB are possibly related and not distinct entities, being two ends of a continuous spectrum of malignant progression (grade 2-grade 4) with anaplastic PXA (grade 3) lying in between. Future WHO classifications will have to possibly redefine these tumors using more confirmatory data from larger studies.

Impact of Grade on Survival in Pleomorphic Xanthoastrocytoma and Low Prevalence of BRAF V600E Mutation

BACKGROUND

The prevalence of BRAFV600E mutations in pleomorphic xanthoastrocytoma (PXA) World Health Organization (WHO) Grade 2 and PXA WHO Grade 3 reported varies from 60% to 80%, yet the prognostic implications remain unclear.

METHODS

We reviewed the demographic and clinicoradiologic data of 20 PXAs WHO Grade 2 and 13 PXAs WHO Grade 3, operated between 2007 and 2020, to ascertain extent of excision, recurrence, progression-free survival (PFS), and overall survival (OS). PXAs WHO Grade 3 were defined by the presence of >5 mitoses/high-power field. PXAs WHO Grade 3 received adjuvant radiation therapy and chemotherapy whereas PXAs received radiation therapy if subtotally excised. All samples were analyzed for the presence of BRAFV600E mutation using DNA obtained from paraffin blocks using droplet-digital polymerase chain reaction.

RESULTS

The median patient age at diagnosis was 22 years with a male preponderance. BRAFV600E mutations were noted in 30% of tumors; 8 PXAs WHO Grade 2 and 2 PXAs WHO Grade 3. Recurrence occurred in 6 of 13 PXA WHO Grade 3 (55%) and 1 of 20 PXAs WHO Grade 2 (5%). At median follow-up of 45 months, the OS was 54 months and 33 months in the PXA WHO Grade 2 and PXA WHO Grade 3 groups, respectively (P = 0.02). OS and PFS did not differ between BRAF-mutated and BRAF-negative tumors.

CONCLUSIONS

BRAFV600E mutations are less frequent in our population than reported in the literature. The BRAF mutation does not significantly impact OS and PFS. PXAs WHO Grade 3 are a distinct clinical entity, associated with worse PFS and OS than PXAs WHO Grade 2.

Autobiographical Case Report of Experiences With Pleomorphic Xanthoastrocytoma

Pleomorphic xanthoastrocytoma is a rare brain tumor of WHO grade II designation. This case report describes the author's experience with the discovery of the tumor, living with the tumor, and eventual treatment and aftermath of how it affected her life and her understanding of the medical system.

Isocitrate Dehydrogenase Wild-type Glial Tumors, Including Glioblastoma

Isocitrate dehydrogenase (IDH) 1 and 2 mutations represent essential components for the diagnosis of diffuse astrocytic tumors and oligodendroglioma. IDH wild-type glial tumors include a wide spectrum of tumors with differences in prognosis and recommended therapeutic approaches. Tumors characterized as molecular glioblastoma in the World Health Organization 2021 classification should be treated according to the glioblastoma therapeutic principles and included in glioblastoma trials. Improving on existing treatments options including targeted and immunotherapy approaches is imperative for most patients with IDH wild-type glial tumors, and enrollment in clinical trials is encouraged.

Pleomorphic Xanthoastrocytoma of the Frontal Lobe in a Child: A Rare Entity

Pleomorphic xanthoastrocytoma (PXA) is an infrequent neoplasm that affects children less commonly than adults. In this case report, a four-year-old boy presented with focal seizures has diagnosed with this tumor in the frontal lobe. Complete surgical resection was achieved, and histopathological features of PXA grade II were observed. During follow-up, the patient showed improvement of the focal seizures. In spite of the pleomorphic features, the PXA had a favorable prognosis.

Differences in treatment patterns and overall survival between grade II and anaplastic pleomorphic xanthoastrocytomas

INTRODUCTION

Pleomorphic xanthoastrocytomas (PXAs) are classified as a grade II neoplasm, typically occur in children, and have favorable prognoses. However, their anaplastic counterparts remain poorly understood and vaguely characterized. In the present study, a large cohort of grade II PXA patients were compared with primary anaplastic PXA (APXA) patients to characterize patterns in treatment and survival.

METHODS

Data were collected from the National Cancer Institute's SEER database. Univariate and multivariate Cox regressions were used to evaluate the prognostic impact of demographic, tumor, and treatment-related covariates. Propensity score matching was used to balance baseline characteristics. Kaplan-Meier curves were used to estimate survival.

RESULTS

A total of 346 grade II PXA and 62 APXA patients were identified in the SEER database between 2000 and 2016. Kaplan-Meier analysis revealed substantially inferior survival for APXA patients compared to grade II PXA patients (median survival: 51 months vs. not reached) (p < 0.0001). After controlling across available covariates, increased age at diagnosis was identified as a negative predictor of survival for both grade II and APXA patients. In multivariate and propensity-matched analyses, extent of resection was not associated with improved outcomes in either cohort.

CONCLUSIONS

Using a large national database, we identified the largest published cohort of APXA patients to date and compared them with their grade II counterparts to identify patterns in treatment and survival. Upon multivariate analysis, we found increased age at diagnosis was inversely associated with survival in both grade II and APXA patients. Receipt of chemoradiotherapy or complete surgical resection was not associated with improved outcomes in the APXA cohort.

Pediatric Pleomorphic Xanthoastrocytoma: A National Database Inquiry on Current Treatment Approaches in the United States

BACKGROUND

Pleomorphic xanthoastrocytomas (PXAs) account for <1% of primary brain tumors, occurring predominantly in children and young adults. Surgical resection serves as the primary treatment for PXAs, while radiotherapy (RT) and chemotherapy protocols remain poorly defined.

AIM

This study aims to determine current care patterns utilized for pediatric patients (≤ 18 years) diagnosed with PXAs and their effect on overall survival.

METHODS

The United States National Cancer Database (NCDB) was queried between 2004 and 2015 for pediatric patients (≤18 years) diagnosed with PXAs.

RESULTS

From the 224 qualifying patients, most patients proceeded with surgery only (78.1%), while 11.6% of patients received both adjuvant RT and chemotherapy. In the 2010-2015 cohort, patients with subtotal resection were associated with poorer prognosis than those with gross-total resection (hazard ratio = 17.44, 95% confidence interval = 2.10-144.90, p < .001). RT and chemotherapy recipients were similarly associated with poorer survival than those treated with surgery only, with p-values of <.001 and respective hazard ratios of 3.82 (95% confidence interval = 1.85-7.90) and 6.68 (95% confidence interval = 3.21-13.89). The key factors impacting the probability of RT delivery involved WHO grade (p < .001) and chemotherapy administration (p < .001). However, WHO grade alone did not significantly impact survival (p-value = .088).

CONCLUSION

Maximally safe resection is the current treatment goal for patients with PXAs. RT and chemotherapy are poorly utilized but had a greater role in managing more aggressive cases of PXAs. Additional research focusing on the impact of adjuvant therapies on tumor progression is needed to better guide treatment decisions.

Clinical Features and Surgical Results of Pediatric Pleomorphic Xanthoastrocytoma: Analysis of 17 Cases with a Literature Review

BACKGROUND

Pediatric pleomorphic xanthoastrocytoma (PXA) is a rare brain tumor. To date, there are few studies dedicated to this kind of pediatric tumor. The aim of this study was to investigate the clinicopathologic characteristics of pediatric PXA.

METHODS

We retrospectively analyzed 17 pediatric patients diagnosed with PXA histologically between July 2009 and December 2018. We also reviewed the relevant literature.

RESULTS

The majority of pediatric PXAs had cystic components and peritumoral edema, and approximately 40% of the tumors had calcifications. All large tumors (≥5 cm) were located in the nontemporal lobes except 1 (P = 0.05). Furthermore, the large tumors were primarily solid-cystic or cystic with mural nodules radiologically, while tumors measuring <5 cm were mainly solid or solid with cystic changes (P = 0.02). All patients underwent surgery, and 15 patients experienced complete tumor removal. Histologically, 11 patients had grade II PXAs and 6 patients had grade III PXAs. After the operation, most of the patients recovered uneventfully and the seizures were well controlled. The mean follow-up time was 43 months. Five patients received radiotherapy or chemotherapy. One patient had tumor recurrence 5 years after the first operation and underwent repeat surgery.

CONCLUSIONS

Cystic components and peritumoral edema could be seen in most pediatric PXAs, and calcification was also not uncommon. The size of the tumor was correlated with the tumor site and radiologic subtype. Maximal safe resection of pediatric PXA is recommended and was shown to be beneficial for seizure control and survival.

Anaplastic Pleomorphic Xanthoastrocytoma: A Case Report and Literature Review

Background

With an incidence of less than 1% among astrocytomas, pleomorphic xanthoastrocytoma (PXA) is rare. When its mitotic activity exceeds 5 mitoses/10 high-power fields, PXA is defined as anaplastic pleomorphic xanthoastrocytoma (APXA). This report documents the clinical manifestations and histopathological characteristics of APXA to help prevent future misdiagnoses.

Case Presentation

A 28-year-old male patient had a sudden limb twitch and visited a local hospital. A head magnetic resonance imaging scan showed large patches of abnormal signal intensity that were approximately 6.0×3.3 cm in size in the right frontal and parietal lobes, with iso- to slightly hypointense signals on T1-weighted images (T1WI) and mixed hyperintense signals on T2-weighted images (T2WI). Optical microscopic imaging found pleomorphic tumor cells with sheet-like growth, as well as foamy tumor cells, multinucleated giant cells, pleomorphic cells with atypical nuclei, and acidophilic bodies. Some areas were densely packed with obvious atypia and visible mitoses. The patient tested positive for glial fibrillary acidic protein (GFAP), vimentin (Vim), neuronal nuclear antigen (NeuN), P53, oligodendrocyte transcription factor-2 (OLIG-2), and ATRX, while he tested negative for synaptophysin (Syn), CD34, S-100, BRAF V600E, and IDH1 R132H. The Ki-67 labeling index was 15%. Genetic sequencing showed that IDH1 and IDH2 genes were wild-type, but that his BRAF gene harbored the V600E mutation.

Conclusion

APXA is a WHO grade III astrocytoma that can be distinguished from WHO grade II PXA according to the level of mitosis. Imaging may help to inform the difficult differentiation between APXA and epithelioid glioblastoma. Nonetheless, a clear diagnosis warrants carrying out a comprehensive analysis, including histomorphological, immunophenotypic, and molecular assessments.

Giant cell glioblastoma in 6-year-old kid: Report of an unusual case

Pediatric giant cell glioblastoma, a highly malignant and lethal tumor, can only be distinguished from glioblastoma multiforme histologically. Though it is said to have a better prognosis, adequate evidence in favor is lacking. Early diagnosis with gross total resection and adjuvant chemotherapy might increase the survival period.

Predictors of outcome in pleomorphic xanthoastrocytoma

Background

Pleomorphic xanthoastrocytomas (PXA) are circumscribed gliomas that typically have a favorable prognosis. Limited studies have revealed factors affecting survival outcomes in PXA. Here, we analyzed the largest PXA dataset in the literature and identify factors associated with outcomes.

Methods

Using the Surveillance, Epidemiology, and End Results (SEER) 18 Registries database, we identified histologically confirmed PXA patients between 1994 and 2016. Overall survival (OS) was analyzed using Kaplan-Meier survival and multivariable Cox proportional hazard models.

Results

In total, 470 patients were diagnosed with PXA (males = 53%; median age = 23 years [14-39 years]), the majority were Caucasian (n = 367; 78%). The estimated mean OS was 193 months [95% CI: 179-206]. Multivariate analysis revealed that greater age at diagnosis (≥39 years) (3.78 [2.16-6.59], P < .0001), larger tumor size (≥30 mm) (1.97 [1.05-3.71], P = .034), and postoperative radiotherapy (RT) (2.20 [1.31-3.69], P = .003) were independent predictors of poor OS. Pediatric PXA patients had improved survival outcomes compared to their adult counterparts, in which chemotherapy (CT) was associated with worse OS. Meanwhile, in adults, females and patients with temporal lobe tumors had an improved survival; conversely, tumor size ≥30 mm and postoperative RT were associated with poor OS.

Conclusions

In PXA, older age and larger tumor size at diagnosis are risk factors for poor OS, while pediatric patients have remarkably improved survival. Postoperative RT and CT appear to be ineffective treatment strategies while achieving GTR confer an improved survival in male patients and remains the cornerstone of treatment. These findings can help optimize PXA treatment while minimizing side effects. However, further studies of PXAs with molecular characterization are needed.

Central Nervous System Cancers, Version 3.2020, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Central Nervous System (CNS) Cancers focus on management of adult CNS cancers ranging from noninvasive and surgically curable pilocytic astrocytomas to metastatic brain disease. The involvement of an interdisciplinary team, including neurosurgeons, radiation therapists, oncologists, neurologists, and neuroradiologists, is a key factor in the appropriate management of CNS cancers. Integrated histopathologic and molecular characterization of brain tumors such as gliomas should be standard practice. This article describes NCCN Guidelines recommendations for WHO grade I, II, III, and IV gliomas. Treatment of brain metastases, the most common intracranial tumors in adults, is also described.

Cerebrospinal Fluid Spread in a Child with Pleomorphic Xanthoastrocytoma: Report with Cytopathologic Evidence

BACKGROUND

Pleomorphic xanthoastrocytoma (PXA), a relatively uncommon, World Health Organization grade II tumor of astrocytic origin, occurs in children and in general carries good prognosis. The recently identified anaplastic PXA (grade III) type shows poor outcome. Rarely, these said tumors can display an aggressive clinical course with features of leptomeningeal spread. Such cases are mostly seen in adults, with rare instances reported in the pediatric age group.

CASE DESCRIPTION

In this report, we describe an 8-year-old child with anaplastic PXA with a rapid downhill course due to cerebrospinal fluid spread. This child is perhaps the first pediatric report in which the cerebrospinal fluid dissemination was established on cytology.

CONCLUSIONS

The case is an indicator of the need for craniospinal screening protocol in patients with PXA, especially the anaplastic variety, both at the time of initial diagnosis and follow-up.

Molecular Features and Prognostic Factors of Pleomorphic Xanthoastrocytoma: A Collaborative Investigation of the Tohoku Brain Tumor Study Group

Pleomorphic xanthoastrocytoma (PXA) is a rare glial tumor, however, its histological differentiation from high-grade gliomas is often difficult. Molecular characteristics may contribute to a better diagnostic discrimination. Prognostic factors of PXA are also important but few relevant reports have been published. This study investigated the molecular features and prognostic factors of PXAs. Seven university hospitals participated in this study by providing retrospective clinical data and tumor samples of PXA cases between 1993 and 2014. Tumor samples were analyzed for immunohistochemical (IHC) neuronal and glial markers along with Ki67. The status of the BRAF and TERT promoter (TERTp) mutation was also evaluated using the same samples, followed by feature extraction of PXA and survival analyses. In all, 19 primary cases (17 PXA and 2 anaplastic PXA) were included. IHC examination revealed the stable staining of nestin and the close association of synaptophysin to NFP. Of the PXA cases, 57% had the BRAF mutation and only 7% had the TERTp mutation. On univariate analysis, age (≥60 years), preoperative Karnofsky performance status (KPS) (≤80%), and marked peritumoral edema were significantly associated with progression-free survival (PFS). No independent factor was indicated by the multivariate analysis. In conclusion, PXA was characterized by positive nestin staining and a few TERTp mutations. The neuronal differential marker and BRAF status may help in diagnosis. Patient age, preoperative KPS, and marked perifocal edema were associated with PFS. The present study is limited because of small number of cases and its retrospective nature. Further clinical study is needed.

Cerebral pleomorphic xanthoastrocytoma mimicking inflammatory granuloma: Two case reports

RATIONALE

Pleomorphic xanthoastrocytoma (PXA) is a rare low-grade glial neoplasm of the central nervous system, which is difficult to distinguish from other neoplastic and non-neoplastic entities. Herein, we report 2 cases of PXA that had been misdiagnosed as an inflammatory granuloma.

PATIENT CONCERNS

The first case was a 22-year-old man who originally presented with a generalized seizure 7 years previously. Magnetic resonance imaging (MRI) revealed a lesion in the right parietal lobe, leading to a diagnosis of inflammatory granuloma. The second case was a 43-year-old man who presented with repeated generalized seizures. MRI revealed a nodular lesion in the left temporal lobe. The magnetic resonance spectrum showed elevated Cho and NAA peaks and a decreased Cr peak. An inflammatory granuloma was suspected.

DIAGNOSIS

After surgical treatment, histopathological examination revealed PXA.

INTERVENTIONS

In the first case, after 10 months of anti-inflammatory treatment, the lesion was significantly reduced in size. During the following 7 years, the patient experienced generalized seizures 3 to 4 times annually. To control intractable epilepsy, the lesion was resected. In the second case, conservative treatment provided no benefit, and then the lesion was resected.

OUTCOMES

In the first case, during a follow-up period of 14 months, the patient was seizure-free with no tumor recurrence. In the second case, after a 6 months of follow-up, the patient remained seizure-free with no tumor recurrence.

LESSONS

The preoperative differential diagnosis of PXA is challenging due to the nonspecific symptoms and imaging manifestations. Considering the potential risk of malignant transformation of PXA, early surgery should be highlighted, and gross total resection is associated with a favorable prognosis.

A Rare Case of Atypical Pleomorphic Neoplasm of Pineal Region in a Child: A Case Report

A 10-year-old boy with no past medical history presented with complaints of nausea and vomiting associated with morning headache for the last month. Ophthalmic nerve and eye exam showed diplopia and strabismus with no other significant findings on physical and neurological examination. Magnetic resonance imaging (MRI) of the brain revealed a homogenous hyperdense and enhancing mass in the pineal region. The endoscopic biopsy of the pineal region demonstrated the cells with highly pleomorphic and hyperchromatic nuclei with an increase in mitotic activity. There were many vessels but no area of vascular proliferation and necrosis. Granular bodies with eosinophilia were identified. Immunohistochemistry was positive for class III b-tubulin with epidermal growth factor receptor (EGFR) staining and glial fibrillary acidic protein (GFAP). Immunostaining was positive for p53, Phosphatase and Tensin homolog (PTEN), and oligodendrocyte transcription factor (OLIG2), while staining for cluster of differentiation (CD)34, cytokeratin (CK), human melanoma black (HMB)45, and isocitrate dehydrogenase (IDH)-R132H mutation was negative, consistent with atypical pleomorphic neoplasm of the pineal region. The patient underwent tumor resection via a sub-occipital trans-tentorial approach, followed by one dose of chemotherapy. The patient experienced a resolution of the symptom and was doing well on his bi-monthly follow up. 

Additional genetic alterations in BRAF-mutant gliomas correlate with histologic diagnoses

INTRODUCTION

Recently, the term "Diffuse glioma, BRAF V600E-mutant" has been recommended for IDH-wildtype gliomas with BRAF p.V600E mutation and without CDKN2A/B deletion. However, additional alterations in gliomas that coexist with BRAF-mutations are poorly defined.

METHODS

We analyzed next-generation sequencing results in 315 cancer-associated genes for 372 gliomas from our institution (2010 to 2017). In addition, we reviewed IDH-WT gliomas with mutation and copy-number alterations available in cBioPortal, to further characterize BRAF-mutant gliomas.

RESULTS

Seventeen (4.6%) showed BRAF mutations. Tumor types included 8 glioblastomas, 2 epithelioid glioblastomas (E-GBM), 2 pleomorphic xanthoastrocytomas (PXA), 1 anaplastic oligodendroglioma, 1 diffuse astrocytoma, and 3 pilocytic astrocytomas. Fifty-three percent (53%) of cases exhibited BRAF-alterations other than p.V600E. The majority of the tumors were localized in the temporal lobe (52.9%). In addition to BRAF mutations, glioblastomas showed concomitant mutations in TP53 (3/8), CDKN2A/B-loss (6/8), TERT-promoter (6/8), and/or PTEN (5/8). Both E-GBMs and PXAs showed CDKN2A/B-loss and BRAF p.V600E with absence of TERTp, TP53, and PTEN mutations. Similar findings were observed in BRAF-mutant infiltrating gliomas from cBioPortal.

CONCLUSIONS

Knowledge of additional alterations that co-occur with BRAF-mutations in gliomas may improve diagnosis and help identify patients that could benefit from targeted therapies. Furthermore, we provide examples of two patients whose tumors responded to BRAF pathway inhibitors, arguing in favor of these therapies in patients with BRAF-mutant gliomas.

Association between adjuvant radiation therapy and overall survival in Pleomorphic Xanthoastrocytoma

BACKGROUND

Pleomorphic Xanthoastrocytoma (PXA) is a low-grade central nervous system (CNS) tumor with a generally favorable prognosis. However, due to its rarity, optimal adjuvant treatment guidelines have not been established by large scale studies. In this study, we investigated the effect of adjuvant radiation therapy (RT) on overall survival (OS) in adult patients with PXA to help address this unanswered question.

METHODS

The National Cancer Database (NCDB) was used to identify adult patients (age ≥ 18 years old) diagnosed with histologically confirmed grade II PXA (2004-2016). Patient demographics, tumor characteristics, and treatment information were collected. Kaplan-Meier curves were generated to study OS, and factors that affected OS were identified using a multivariate Cox proportional hazards (CPH) model.

RESULTS

A total of 546 patients were identified. The average age of patients at diagnosis was 36.6 years old, and overall median survival was 128.6 months. RT was used to treat 179 (33.3 %) patients. Those who received RT had a shorter median OS (33.3 months) compared to those who did not (>128.6 months, p < 0.001). Our multivariate model demonstrated receiving RT was independently associated with a significantly higher risk of death (hazard ratio [HR] = 4.28, 95 % confidence interval [CI] = 1.77-10.38, p = .0013). Patients ≥65 years of age also demonstrated significantly higher risk of death (HR = 2.20, CI = 1.54-4.16, p = .006) and had a decreased median OS (26.0 months).

CONCLUSION

In adults with PXA, treatment with RT is independently associated with a significantly higher risk of mortality. The routine use of this modality in treating PXA warrants further study.

An anaplastic pleomorphic xanthoastrocytoma with periventricular extension: An autopsy case report and review of the literature

Pleomorphic xanthoastrocytomas (PXAs) are rare low-grade astrocytic tumors that typically present as superficial nodular cystic tumors of the cerebrum attached to the leptomeninx. Histologically, they are pleomorphic, hypercellular glial neoplasms. Despite the presence of microscopic pleomorphism, patients' postoperative prognosis is generally good. Anaplastic PXAs (APXAs) have a high mitotic index and patients with APXAs have a worse prognosis than patients with PXAs. Here, we report an autopsy case of APXA initially diagnosed as PXA. After gross total resection, the tumor recurred and was diagnosed as an APXA; thereafter, the patient died. An autopsy revealed that the tumor had relapsed at the primary site and had spread to the leptomeningeal space while concurrently invading the cerebrum including the periventricular area forming multifocal lesions. The histological findings of the autopsy were similar to those for epithelioid glioblastoma (EGBM) and small cell glioblastoma (SCGBM). In particular, the periventricular area with multifocal lesions was composed of SCGBM-like cells. It has been shown that multifocal lesions are frequently identified in patients with SCGBM. This is the first histopathologically confirmed case of APXA-related tumor presenting with periventricular extension and multifocal lesion formation. The periventricular extension might be a feature of PXAs and APXAs. However, suspected periventricular spread on imaging in past cases of PXAs and APXAs might instead represent the malignant transformation of these tumors to glioblastoma-like high-grade tumors, which often show SCGBM-like histological patterns.

Spinal Pleomorphic Xanthoastrocytoma: Case Report and Literature Review

Pleomorphic xanthoastrocytoma (PXA) is an uncommon central nervous system neoplasm with an overall favorable survival prognosis. Metastatic spread of PXA to the spinal cord and the cauda equina is rare and may have a different clinicopathologic course. Treatment and prognostic outcomes, in this context, are not well defined. We discuss a case of a 30-year-old patient with known cerebral PXA presenting with metastatic spinal anaplastic PXA and present a literature analysis of treatment outcomes.

Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma

The phenomenon of unstable expression of gap junction's proteins connexins remains a "visiting card" of astrocytic tumors with various degrees of malignancy. At the same time, it stays unclear what is detected by the positive expression of connexins in astrocytic tumors: gap junctions, hemi-channels, or connexin proteins in cytosol. In the present work, for the first time, we demonstrate an ultrastructural evidence of gap junctions in pleomorphic xanthoastrocytoma, a rare primary brain tumor, the intercellular characteristics of which are poorly studied and remain very discursive and controversial. The primary tumor mass was resected during craniotomy from a 57-old patient diagnosed with pleomorphic xanthoastrocytoma Grade II based on the histopathological analysis. The immunohistochemical study was conducted with primary antibodies: Neurofilament, Myelin basic protein, Glial fibrillary acidic protein, and Synaptophysin. For electron microscopic examination fragments of tumor tissue were fixed in a glutaraldehyde, postfixed in a 1% OsO₄, dehydrated and embedded into resin. After the detailed clinical, histological, and immunohistochemical study we revealed some ultrastructural characteristics of the tumor, as well as the first evidence of direct intercellular connection between the tumor cells via gap junctions. Regularly arranged gap junctions connected the somas of xanthastrocytes with dark cytoplasm containing lipid drops. Besides the localization between the cell bodies, from one to several gap junctions were found between the branches of xanthoastrocytoma in tumor intercellular space in close proximity to tumor cell. Our results may indicate gap junctions as a possible structure for intercellular communication between pleomorphic xanthoastrocytoma cells.

Pleomorphic xanthoastrocytoma in the posterior fossa: a case report with advanced neuroimaging findings

Pleomorphic xanthoastrocytoma (PXA) is a rare glioma usually occurring in children and young adults. It is a benign World Health Organization (WHO) grade II tumor that accounts for <1% of all astrocytomas. Its occurrence in the infratentorial compartment is rare, and the cerebellum is the most common of the unusual locations. Few case reports have described conventional imaging features of these tumors, but none has reported the advanced magnetic resonance (MR) neuroimaging features in dynamic susceptibility perfusion-weighted imaging (DSC-PWI), diffusion weighted-imaging (DWI) and MR spectroscopy. Therefore, the purpose of this study is to report a case of PXA in the cerebellum of a 28-year-old patient and discuss the MR advanced imaging characteristics compared to the more common PXA supratentorial type.

Spinal Pleomorphic Xanthoastrocytoma With a QKI-RAF1 Fusion

Pleomorphic xanthoastrocytoma (PXA) is a slow-growing neoplasm that predominantly affects the pediatric and young adult population. This neoplasm has a good prognosis, with a median 10-year survival rate of 70%. The majority of tumors are supratentorial and arise in the temporal lobe, while spinal tumors are extremely rare, with only 8 reported cases. Molecular perturbations involving the MAPK/ERK signaling pathway have been described in PXAs. The most common mutation is BRAF V600E in 60%-80% of cases. Other mechanisms activating this pathway in the absence of this mutation are rare and include CRAF (RAF1) fusion genes. We report a PXA case in the cervical spinal cord of a 49-year-old man with slowly progressive coordination difficulties and extremity numbness. The tumor was negative for the V600E mutation, but 2 RNA sequencing platforms detected a QKI-RAF1 fusion (t(6; 3)(q26; p25)), which has not been previously reported in PXAs. This fusion is known to activate MAPK/ERK and PI3K/mTOR signaling. Although first- and second-generation RAF inhibitors are predicted to be ineffective, this fusion may be targetable by the novel RAF inhibitor LY3009120 and to some extent by the MEK inhibitor trametinib. Genetic analysis to screen for MAPK/ERK pathway mutations is warranted on PXAs negative for the V600E mutation.

Using personalized medicine in gliomas: a genomic approach to diagnosis and overcoming treatment resistance in a case with pleomorphic xanthoastrocytoma

INTRODUCTION

A patient who was initially considered to have a glioblastoma (GBM) had molecular analysis, showing that it was a pleomorphic xanthoastrocytoma (PXA). Up to 78% of PXA tumors have BRAF V600E mutations. Primary brain tumors with BRAF mutations can have a good response to BRAF MEK inhibitors (BRAF MEKi), and there may be a synergistic response when combined with autophagy inhibitors.

PRESENTATION OF THE CASE

A 20-year-old man found to have a large brain mass with midline shift underwent resection. He was diagnosed with "GBM" and treated with radiation and temozolomide with subsequent disease recurrence. Review of histology showed malignant PXA with BRAF V600E mutation. Treatment with Dabrafenib and Trametinib was started, and tumor size increased in size after 14 months of treatment. Given studies showing that resistance to BRAF inhibition can be overcome by autophagy inhibition, chloroquine was added. Patient has been on "triple" therapy for 15 months and has radiographically Stable Disease. At MCC, 3% of patients with gliomas have BRAF mutations who could potentially benefit from this combination therapy.

CONCLUSION

This is the first report of a PXA patient receiving therapy with BRAF MEKi and an autophagy inhibitor with prolonged stable disease. This patient highlights the importance of a molecular interrogation in gliomas to provide an integrated diagnosis and effective treatment. This may be useful in up to 3% of glioma patients with BRAF mutations. Molecular testing in neuro-oncology is providing new avenues of diagnosis and treatment, and detailed molecular interrogation should be considered routine.

Pleomorphic xanthoastrocytoma: a brief review

Pleomorphic xanthoastrocytoma (PXA) is a rare primary CNS tumor. Recent advances in the molecular characterization are helping to define subtypes of tumor. The discovery of BRAF mutations within a substantial percentage of PXA fosters a clearer understanding of the pathophysiology of these tumors with clear prognostic and therapeutic implications. These findings are expected to provide insight into the spectrum of clinical behavior observed in PXA, ranging from cure with surgery to diffuse dissemination throughout the neuraxis. This review details the clinical presentation including radiographic appearance of PXA. Pathology, including molecular pathology is discussed. Therapeutic management including surgical resection, radiotherapy and systemic therapies are reviewed.

Molecular Profiling Reclassifies Adult Astroblastoma into Known and Clinically Distinct Tumor Entities with Frequent Mitogen-Activated Protein Kinase Pathway Alterations

BACKGROUND

Astroblastoma (ABM) is a rare glial brain tumor. Recurrent meningioma 1 (MN1) alterations have been recently identified in most pediatric cases. Adolescent and adult cases, however, remain molecularly poorly defined.

MATERIALS AND METHODS

We performed clinical and molecular characterization of a retrospective cohort of 14 adult and 1 adolescent ABM.

RESULTS

Strikingly, we found that MN1 fusions are a rare event in this age group (1/15). Using methylation profiling and targeted sequencing, most cases were reclassified as either pleomorphic xanthoastrocytomas (PXA)-like or high-grade glioma (HGG)-like. PXA-like ABM show BRAF mutation (6/7 with V600E mutation and 1/7 with G466E mutation) and CD34 expression. Conversely, HGG-like ABM harbored specific alterations of diffuse midline glioma (2/5) or glioblastoma (GBM; 3/5). These latter patients showed an unfavorable clinical course with significantly shorter overall survival (p = .021). Mitogen-activated protein kinase pathway alterations (including FGFR fusion, BRAF and NF1 mutations) were present in 10 of 15 patients and overrepresented in the HGG-like group (3/5) compared with previously reported prevalence of these alterations in GBM and diffuse midline glioma.

CONCLUSION

We suggest that gliomas with astroblastic features include a variety of molecularly sharply defined entities. Adult ABM harboring molecular features of PXA and HGG should be reclassified. Central nervous system high-grade neuroepithelial tumors with MN1 alterations and histology of ABM appear to be uncommon in adults. Astroblastic morphology in adults should thus prompt thorough molecular investigation aiming at a clear histomolecular diagnosis and identifying actionable drug targets, especially in the mitogen-activated protein kinase pathway.

IMPLICATIONS FOR PRACTICE

Astroblastoma (ABM) remains a poorly defined and controversial entity. Although meningioma 1 alterations seem to define a large subset of pediatric cases, adult cases remain molecularly poorly defined. This comprehensive molecular characterization of 1 adolescent and 14 adult ABM revealed that adult ABM histology comprises several molecularly defined entities, which explains clinical diversity and identifies actionable targets. Namely, pleomorphic xanthoastrocytoma-like ABM cases show a favorable prognosis whereas high-grade glioma (glioblastoma and diffuse midline gliome)-like ABM show significantly worse clinical courses. These results call for in-depth molecular analysis of adult gliomas with astroblastic features for diagnostic and therapeutic purposes.

Solitary Extra-axial Intracranial Primary Meningeal Pleomorphic Xanthoastrocytoma: An Extremely Rare Case

BACKGROUND

Pleomorphic xanthoastrocytomas (PXAs) are a rare type of astrocytoma, which, similar to other gliomas, can rarely arise from glial nests in the meninges, manifesting as an extra-axial mass. We describe a solitary extra-axial intracranial primary meningeal PXA in the pediatric age group, which was masquerading as a tentorial meningioma.

CASE DESCRIPTION

A 9-year-old girl presented with features of raised intracranial pressure. Imaging revealed a dural-based mass in the tentorial region suggestive of a meningioma. This suspicion was further strengthened by intraoperative visualization of an extra-axial tumor with wide tentorial attachment. Near-total excision was achieved. Histopathologic examination established the diagnosis of PXA. Given the tumor's apparent meningeal origin and lack of connection with brain parenchyma in imaging and intraoperative findings, primary meningeal PXA was diagnosed. The absence of coexisting tumor foci on spinal magnetic resonance imaging further refined the diagnosis as solitary extra-axial intracranial primary meningeal PXA. The patient received radiotherapy for the residual tumor and was doing well at 6 months after presentation; however, she was lost to follow-up after that.

CONCLUSIONS

Solitary extra-axial intracranial primary meningeal PXA is an extremely rare entity with only 3 reported cases in the literature including the present case. This is the first report of such a tumor in a pediatric patient. This report also highlights that primary meningeal PXA can manifest as an extra-axial mass lesion and may warrant inclusion in the differential diagnosis of extra-axial mass lesions.

Suprasellar pleomorphic xanthoastrocytoma: A case report

Background:

Pleomorphic xanthoastrocytoma (PXA) is a rare form of astrocytic neoplasm most commonly found in children and young adults. This neoplasm, which is classified as a Grade II tumor by the World Health Organization classification of tumors of the central nervous system, carries a relatively favorable outcome. It is usually found supratentorially in cortical regions of the cerebral hemispheres, and as such, presenting symptoms are similar to other supratentorial cortical neoplasms; with seizures being a common initial symptom. Due to the rarity of this type of neoplasm, PXA arising elsewhere in the brain is often not included in the initial differential diagnosis.

Case Description:

This report presents an extremely rare patient with PXA arising in the suprasellar region who presented with progressive peripheral vision loss. Magnetic resonance imaging of the brain demonstrated a heterogeneous suprasellar mass with cystic and enhancing components initially; the most likely differential diagnosis was craniopharyngioma. The patient underwent endoscopic endonasal resection of the tumor. Microscopically, the tumor was consistent with a glial neoplasm with variable morphology. Based on these findings along with further immunohistochemical workup, the patient was diagnosed with a PXA arising in the suprasellar region. At the 1-year follow-up, the patient remained free of recurrence. Although rare PXA originating in other uncommon locations, such as the spinal cord, cerebellum, the ventricular system, and the pineal region have been previously described.

Conclusion:

Although rare, PXA should be included in the differential diagnosis for solid-cystic tumors arising in the suprasellar region in young adults.

Pathologic and molecular aspects of anaplasia in circumscribed gliomas and glioneuronal tumors

Many breakthroughs have been made in the past decade regarding our knowledge of the biological basis of the diffuse gliomas, the most common primary central nervous system (CNS) tumors. These tumors as a group are aggressive, associated with high mortality, and have a predilection for adults. However, a subset of CNS glial and glioneuronal tumors are characterized by a more circumscribed pattern of growth and occur more commonly in children and young adults. They tend to be indolent, but our understanding of anaplastic changes in these tumors continues to improve as diagnostic classifications evolve in the era of molecular pathology and more integrated and easily accessible clinical databases. The presence of anaplasia in pleomorphic xanthoastrocytomas and gangliogliomas is assigned a WHO grade III under the current classification, while the significance of anaplasia in pilocytic astrocytomas remains controversial. Recent data highlight the association of the latter with aggressive clinical behavior, as well as the presence of molecular genetic features of both pilocytic and diffuse gliomas, with the recognition that the precise terminology remains to be defined. We review the current concepts and advances regarding histopathology and molecular understanding of pilocytic astrocytomas, pleomorphic xanthoastrocytomas, and gangliogliomas, with a focus on their anaplastic counterparts.

Neurosurgical treatment of pediatric pleomorphic xanthoastrocytomas: long-term follow-up of a single-institution, consecutive series of 12 patients

OBJECTIVE

The authors conducted a study to delineate the long-term results of the surgical treatment of pediatric pleomorphic xanthoastrocytomas (PXAs).

METHODS

All consecutive children and adolescents (0-20 years) who underwent primary tumor resection for a PXA during the years 1972-2015 were included in this retrospective study on surgical morbidity, mortality rate, academic achievement, and/or work participation. Gross motor function and activities of daily living were scored according to the Barthel Index.

RESULTS

Of the 12 patients, 8 patients were in the 1st decade of life and 4 in the 2nd. The male/female ratio was 6:6. No patient was lost to follow-up. One patient presented with severe progressive tumor disease and died within 3 months after repeated resection. Another child died 3 days following a second surgical procedure involving gross-total resection (GTR) 8 years after the initial operation. The other 10 patients were alive at the latest follow-up when they reached the median age of 34 years (range 11-60 years). The median follow-up duration was 22 years (range 2-41 years). Barthel Index score was 100 in all 10 survivors. A total 18 tumor resections were performed. Five patients underwent a second tumor resection after MRI/CT confirmed recurrent tumor disease, from 6 months up to 17 years after the initial operation. Only one of our patients received adjuvant therapy: a 19-year-old male who underwent resection (GTR) for a right-sided temporal tumor in 1976. This particular tumor was originally classified as astrocytoma WHO grade IV, and postoperative radiotherapy (54 Gy) was given. The histology was reclassified to that of a PXA. Seven of 8 children whose primary tumor resection was performed more than 20 years ago are alive as of this writing-i.e., 88% observed 20-year survival. These are long-term survivors with good clinical function and all are in full- or part-time work.

CONCLUSIONS

Pediatric patients with PXA can be treated with resection alone with rewarding results. Recurrences are not uncommon, but repeated surgery is well tolerated and should be considered in low-grade cases before adjuvant therapy is implemented. Follow-up including repeated MRI is important during the first postoperative years, since individual patients may have a more aggressive tumor course.

A rare clinical presentation: a pleomorphic xanthoastrocytoma presenting with intracerebral haemorrhage and metastasizing vigorously-case report and review of the literature

Metastasis of an intracranial tumour is not a common situation in our daily neurosurgical practice. Pleomorphic xanthoastrocytoma is also a rare glial tumour with relatively a favourable prognosis among other CNS pathologies. Here, we present an anaplastic pleomorphic xanthoastrocytoma case which shows both haematogenous and lymphatic metastasis which is described first time in the up-to-date literature. Our case is a 17-year-old male operated for a right occipital intra-axial lesion with a diagnosis of anaplastic pleomorphic xanthoastrocytoma which recurs 5 years later and metastasize vigorously through haematogenous and lymphatic routes. A rare-presenting symptom for this pathology is also intracerebral haemorrhage. This is the ninth case report in the literature which presents initially with this entity.

The genetic landscape of anaplastic pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is an astrocytic neoplasm that is typically well circumscribed and can have a relatively favorable prognosis. Tumor progression to anaplastic PXA (WHO grade III), however, is associated with a more aggressive biologic behavior and worse prognosis. The factors that drive anaplastic progression are largely unknown. We performed comprehensive genomic profiling on a set of 23 PXAs from 19 patients, including 15 with anaplastic PXA. Four patients had tumor tissue from multiple recurrences, including two with anaplastic progression. We find that PXAs are genetically defined by the combination of CDKN2A biallelic inactivation and RAF alterations that were present in all 19 cases, most commonly as CDKN2A homozygous deletion and BRAF p.V600E mutation but also occasionally BRAF or RAF1 fusions or other rearrangements. The third most commonly altered gene in anaplastic PXA was TERT, with 47% (7/15) harboring TERT alterations, either gene amplification (n = 2) or promoter hotspot mutation (n = 5). In tumor pairs analyzed before and after anaplastic progression, two had increased copy number alterations and one had TERT promoter mutation at recurrence. Less commonly altered genes included TP53, BCOR, BCORL1, ARID1A, ATRX, PTEN, and BCL6. All PXA in this cohort were IDH and histone H3 wildtype, and did not contain alterations in EGFR. Genetic profiling performed on six regions from the same tumor identified intratumoral genomic heterogeneity, likely reflecting clonal evolution during tumor progression. Overall, anaplastic PXA is characterized by the combination of CDKN2A biallelic inactivation and oncogenic RAF kinase signaling as well as a relatively small number of additional genetic alterations, with the most common being TERT amplification or promoter mutation. These data define a distinct molecular profile for PXA and suggest additional genetic alterations, including TERT, may be associated with anaplastic progression.

Complete Remission of an Extracranially Disseminated Anaplastic Pleomorphic Xanthoastrocytoma With Everolimus: A Case Report and Literature Review

BACKGROUND

Surgical resection is the treatment of choice for pleomorphic xanthoastrocytoma, while chemotherapy and radiation therapy are typically used in patients with anaplasia, metastasis, or sometimes in subtotally resected cases, especially upon recurrence. Extracranial dissemination has been only rarely reported. We describe a five year old boy with the rare occurrence multiply recurrent and extracranially disseminated anaplastic pleomorphic xanthoastrocytoma. A complete resolution of his tumor was achieved for greater than two years thus far after administering everolimus.

METHODS

We performed a comprehensive literature review of all pleomorphic xanthoastrocytoma cases; 359 cases were described, and 132 of these individuals were less than 18 years of age.

RESULTS

Gross total resection was achieved in only 132 (36.7%) cases, while additional therapy was administered in 186 patients. Only four patients in additon to our own have been documented with extracranial dissemination (four of five in the pediatric population); two patients who succumbed to their disease underwent subtotal resection of the primary tumor.

CONCLUSIONS

We report the first patient with extracranially disseminated anaplastic pleomorphic xanthoastrocytoma to be successfully maintained on everolimus as a single oral chemotherapy agent with complete resolution of the tumor. Pleomorphic xanthoastrocytoma can rarely disseminate extracranially in the pediatric population, hence pathologists and neuro-oncologists should be aware of this possibility.

Retinal anaplastic pleomorphic xanthoastrocytoma unassociated with phakomatosis

Purpose

To present a rare anaplastic form of retinal pleomorphic xanthoastrocytoma (PXA) unassociated with phakomatosis.

Methods

A 9-year-old girl, presented with a rapidly growing unilateral intraocular white mass unresponsive to intra-arterial chemotherapy, underwent enucleation with the clinical suspicion of retinoblastoma versus malignant astrocytoma.

Results

Histopathology revealed pleomorphic cells with rosenthal fibers, mitosis, and necrosis. Immunohistochemistry confirmed the diagnosis of anaplastic pleomorphic xanthoastrocytoma (aPXA). The patient had no signs of phakomatosis.

Conclusion

Retinal PXA may occur in patients without phakomatosis and rarely progress toward malignant transformation.

Pleomorphic xanthoastrocytomas of adults: MRI features, molecular markers, and clinical outcomes

Fifty adult patients with pathologically-confirmed pleomorphic xanthoastrocytomas (PXAs) were retrospectively analyzed. Adult PXAs appeared as a single lesion in 47 patients and multiple lesions in 3 patients. Temporal lobe was the most common location (17/50). Twenty-two cases were superficial with obvious meningeal contact and 9 were closely adjacent to lateral ventricles. Three imaging patterns were differentiated, including a predominantly solid mass with or without cystic changes (n = 33), a predominantly cystic mass with an obvious mural nodule (n = 14), and a predominantly cystic mass with an uneven wall thickness (n = 3). The mean tumoral apparent diffusion coefficient (ADC) was 0.83 ± 0.17 × 10⁻³ mm²/s, and the mean ADC ratio was 1.02 ± 0.22. The V-raf murine sarcoma viral oncogenes homolog B1 (BRAF)^V600E mutation was found in 12 of 29 patients. In 36 patients with isocitrate dehydrogenases 1 and 2 (IDH1/2) data, only one had IDH1 mutation and no patient had IDH2 mutation. Anaplastic features were common (24/50) and significantly associated with high rates of recurrence or progression (P < 0.001). In conclusion, this study expands our knowledge on the MRI features, molecular markers, and clinical outcomes of adult PXAs, to some extent different from pediatric PXAs.