Pleomorphic xanthoastrocytoma: long-term results of surgical treatment and analysis of prognostic factors

Noninvasive prediction of BRAF V600E mutation status of pleomorphic xanthoastrocytomas with MRI morphologic features and diffusion-weighted imaging

OBJECTIVES

Seeking a noninvasive predictor for BRAF V600E mutation status of pleomorphic xanthoastrocytomas (PXAs) is essential for their prognoses and therapeutic use of BRAF inhibitors. We aimed to noninvasively diagnose BRAF V600E-mutated PXAs using MRI morphologic, DWI and clinical parameters.

METHODS

The clinical findings, anatomical MRI characteristics, and diffusion parameters of 36 pathologically confirmed PXAs were retrospectively analyzed, and BRAF V600E-mutated (n = 16) and wild-type (n = 20) groups were compared. A binary logistic-regression analysis was performed, and a ROC curve was calculated to determine the independent predictors of BRAF V600E mutation status, diagnostic accuracy, and optimal cut-off value.

RESULTS

A comparison of findings between groups showed that BRAF V600E-mutated PXAs were more frequent in children and young adults (≤ 35 years; P = 0.042) who often had histories of seizures (P = 0.004). Furthermore, BRAF V600E-mutated PXAs generally presented as solitary masses (P = 0.024), superficial locations with meningeal attachment (P < 0.001), predominantly cystic with mural nodules (P = 0.005), and had greater minimal ADC ratio (ADCratio) values of the tumor and peritumoral edema (P < 0.001). Binary logistic regression showed that age ≤ 35 years, solitary mass, superficial locations with meningeal attachment, and a greater minimal ADCratio of the tumor were independent predictors of BRAF V600E-mutated PXAs. The combination of all four independent predictors resulted in the highest sensitivity (100%) and specificity (90%), with AUC = 0.984.

CONCLUSION

The BRAF V600E mutation status of PXAs could be noninvasively predicted using clinical and MRI characteristics.

CRITICAL RELEVANCE STATEMENT

The noninvasive diagnostic criteria for BRAF V600E-mutated PXAs could offer guidance for the administration of BRAF V600E mutation inhibitors in the future.

Exploring prognostic factors and treatment strategies for long-term survival in pleomorphic xanthoastrocytoma patients

Pleomorphic xanthoastrocytomas (PXA) are rare, accounting for < 1% of all astrocytomas. Literature on the clinical course and treatment outcomes of PXAs is limited. The study aimed to determine prognosis and treatment strategies for PXAs. Patients who had PXAs surgery between 2000-2021 were retrospectively analyzed for demographics and radiological characteristics. Initial and salvage treatment outcomes were recorded. Overall, 40 and 9 patients had grade 2 and 3 PXAs; their 5-year progression-free survival (PFS) rates were 75.8% and 37.0%, respectively (p = 0.003). Univariate analysis revealed that strong T1 enhancement (p = 0.036), infiltrative tumor margins (p < 0.001), peritumoral edema (p = 0.003), WHO grade (p = 0.005), and gross total resection (p = 0.005) affected the PFS. Multivariate analysis revealed that the WHO grade (p = 0.010) and infiltrative tumor margins (p = 0.008) influenced the PFS. The WHO grade (p = 0.027) and infiltrative tumor margins (p = 0.027) also affected the overall survival (OS). Subgroup analysis for grade 2 PXAs revealed no significant associations between adjuvant radiation therapy and the PFS and OS. This study highlighted the heterogeneous nature of PXAs and its impact on patient prognosis. Infiltrative tumor margins emerged as a key prognostic factor. Our findings have emphasized the prognostic relevance of radiological features and the need for larger studies on comprehensive management.

Advances in Molecular Pathology, Diagnosis and Treatment of Spinal Cord Astrocytomas

Spinal cord astrocytoma (SCA) is a rare subtype of astrocytoma, posing challenges in diagnosis and treatment. Low-grade SCA can achieve long-term survival solely through surgery, while high-grade has a disappointing prognosis even with comprehensive treatment. Diagnostic criteria and standard treatment of intracranial astrocytoma have shown obvious limitations in SCA. Research on the molecular mechanism in SCA is lagging far behind that on intracranial astrocytoma. In recent years, huge breakthroughs have been made in molecular pathology of astrocytoma, and novel techniques have emerged, including DNA methylation analysis and radiomics. These advances are now making it possible to provide a precise diagnosis and develop corresponding treatment strategies in SCA. Our aim is to review the current status of diagnosis and treatment of SCA, and summarize the latest research advancement, including tumor subtype, molecular characteristics, diagnostic technology, and potential therapy strategies, thus deepening our understanding of this uncommon tumor type and providing guidance for accurate diagnosis and treatment.

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.

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.

Adolescent and young adult glioma: systematic review of demographic, disease, and treatment influences on survival

BACKGROUND

Prognostic factors in adolescent and young adult (AYA) glioma are not well understood. Though clinical and molecular differences between pediatric and adult glioma have been characterized, their application to AYA populations is less clear. There is a major need to develop more robust evidence-based practices for managing AYA glioma patients.

METHODS

A systematic review using PRISMA methodology was conducted using multiple databases with the objective of identifying demographic, clinical, molecular and treatment factors influencing AYA glioma outcomes.

RESULTS

40 Studies met inclusion criteria. Overall survival was highly variable across studies depending on glioma grade, anatomic compartment and cohort characteristics. Thirty-five studies suffered from high risk of bias in at least one domain. Several studies included older adults within their cohorts; few captured purely AYA groups. Despite study heterogeneity, identified favorable prognosticators included younger age, higher functional status at diagnosis, low-grade pathology, oligodendroglioma histology and increased extent of surgical resection. Though isocitrate dehydrogenase (IDH) mutant status was associated with favorable prognosis, validity of this finding within AYA was compromised though may studies including older adults. The prognostic influence of chemotherapy and radiotherapy on overall survival varied across studies with conflicting evidence.

CONCLUSION

Existing literature is heterogenous, at high risk of bias, and rarely focused solely on AYA patients. Many included studies did not reflect updated pathological and molecular AYA glioma classification. The optimal role of chemotherapy, radiotherapy, and targeted agents cannot be determined from existing literature and should be the focus of future studies.

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.

Cerebellar pleomorphic xanthoastrocytoma in the setting of neurofibromatosis type-I: Does it portend a different prognosis? A case report and systematic review

BACKGROUND

Pleomorphic xanthoastrocytoma (PXA) is a rare brain tumor occurring supra- and infra-tentorially in both young adults and children. PXA is a benign tumor with a favorable prognosis. It is not traditionally considered as a neurofibromatosis type 1 (NF-1)-associated lesion, and its prognosis remains largely unknown, on the contrary to non-NF-1 PXA tumors.

OBJECTIVE

Herein, we present a rare case of cerebellar PXA in a patient with NF-1 and performed systematic review of NF-1-associated PXA.

METHOD

We present a case of NF-1-associated PXA arising in the cerebellar region. We also reviewed the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines to identify published cases of cerebellar vs. non-cerebellar NF-1-associated PXA and NF1 vs. non-NF1 PXAs, highlighting their management paradigm, prognosis, and outcomes.

RESULT

Our systematic review yielded only four previously reported cases of NF-1-associated PXAs in the cerebellar region. Our review suggests that infratentorial PXAs have a higher recurrence and lower survival rates than non-cerebellar NF-1-associated PXAs and non-NF1 PXAs in general.

CONCLUSION

Early and precise diagnosis is important for these lesions with the aid of imaging features, histology, immunohistochemistry, and genetic markers. Surgical resection with goal of GTR remains the mainstay management strategy for PXA, with adjuvant therapy usually reserved for anaplastic or malignant lesions. The identification of BRAF-V600E mutation and role of BRAF inhibitors hold promise as a diagnostic tool and treatment modality, respectively, for PXAs, and their relationship to NF-1 is worth further exploration.

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.

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.

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.

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.

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.

MR Imaging Features of Anaplastic Pleomorphic Xanthoastrocytoma Mimicking High-Grade Astrocytoma

BACKGROUND AND PURPOSE

Anaplastic pleomorphic xanthoastrocytoma, which has been recently defined as a distinct entity in the 2016 World Health Organization classification, may exhibit aggressive clinical behavior and relatively worse prognosis than pleomorphic xanthoastrocytoma. This study aimed to investigate whether there were any differences in MR imaging characteristics between these 2 tumors.

MATERIALS AND METHODS

This retrospective study included 9 patients with anaplastic pleomorphic xanthoastrocytoma and 10 patients with pleomorphic xanthoastrocytoma who underwent MR imaging before an operation. DWI was performed in 17 patients (8 with anaplastic pleomorphic xanthoastrocytoma, 9 with pleomorphic xanthoastrocytoma); and DSC-PWI, in 9 patients (5 with anaplastic pleomorphic xanthoastrocytoma, 4 with pleomorphic xanthoastrocytoma). Demographics, conventional imaging characteristics (location, size, cystic degeneration, enhancement, peritumoral edema, and leptomeningeal contact), minimum relative ADC ratio, and maximum relative CBV ratio were evaluated between the anaplastic pleomorphic xanthoastrocytoma and pleomorphic xanthoastrocytoma groups.

RESULTS

Anaplastic pleomorphic xanthoastrocytoma was more likely to demonstrate high-grade features than pleomorphic xanthoastrocytoma, including greater maximum tumor diameter (4.7 ± 0.6 cm versus 3.1 ± 1.1 cm, P = .001), more frequent heterogeneous contrast enhancement of solid portions (88.9% versus 20.0%, P = .01), more obvious peritumoral edema (2.3 ± 0.9 cm versus 1.0 ± 0.9 cm, P = .008), lower minimum relative ADC on DWI (1.0 ± 0.2 versus 1.5 ± 0.4, P = .008), and higher maximum relative CBV on DSC-PWI (2.6 ± 0.8 versus 1.6 ± 0.2, P = .036).

CONCLUSIONS

Anaplastic pleomorphic xanthoastrocytomas often have more aggressive MR imaging features mimicking high-grade astrocytomas than pleomorphic xanthoastrocytomas. DWI and DSC-PWI might be useful in the characterization and differentiation of anaplastic pleomorphic xanthoastrocytoma and pleomorphic xanthoastrocytoma.

An Infratentorial Pure Pleomorphic Xanthoastrocytoma Arising from Middle Cerebellar Peduncle: A Rare Location of an Uncommon Tumor

BACKGROUND

Pleomorphic xanthoastrocytomas are rare tumors of glial origin comprising <1% of all astrocytic tumors of brain. These tumors are rare in the infratentorial compartment and were not known to arise from the middle cerebellar peduncle.

CASE DESCRIPTION

We discuss the case of a 16-year-boy who presented with altered sensorium and features of increased intracranial pressure and was found to have a 4 × 4 × 3 cm mass arising from the middle cerebellar peduncle.

CONCLUSION

We also discuss the histopathologic features of these tumors suggesting their resemblance to other maldevelopmental tumors, the rarity of pure World Health Organization grade II pleomorphic xanthoastrocytoma in the infratentorial compartment, as well as the appropriate management.

Dabrafenib in BRAFV600-mutated anaplastic pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is a rare brain tumor. Anaplastic features are found in 20-30% of cases of PXA and are associated with poor outcomes. Typical treatment is with gross total resection, followed by radiation therapy and cytotoxic chemotherapy at relapse. BRAFV600 mutations have been identified in 38-60% of patients with PXA. Several case reports and small case series have identified clinical benefit with BRAF inhibition in patients with BRAFV600-mutated PXA. We report the second published case of successful treatment with the BRAF inhibitor dabrafenib in a female patient with relapsed anaplastic PXA with a BRAFV600 mutation, and the first published case of dabrafinib treatment following intolerance to vemurafenib.

Rare Primary Central Nervous System Tumors Encountered in Pediatrics

As part of the special issue on Pediatric Neuro-Oncology, this article will focus on 4 of the rarer tumors in this spectrum, including atypical teratoid rhabdoid tumors, embryonal tumors with multilayered rosettes, choroid plexus tumors, and pleomorphic xanthoastrocytoma. Incidence and current understanding of the molecular pathogenesis of these tumors are discussed, and avenues of therapy both current and prospective are explored.

Pleomorphic Xanthoastrocytoma: Natural History and Long-Term Follow-Up

Prognostic significance of histological anaplasia and BRAF V600E mutation were retrospectively evaluated in 74 patients with pleomorphic xanthoastrocytoma (PXA). Median age at diagnosis was 21.5 years (31 pediatric, 43 adult) and median follow-up 7.6 years. Anaplasia (PXA-AF), defined as mitotic index ≥ 5/10 HPF and/or presence of necrosis, was present in 33 cases. BRAF V600E mutation was detected in 39 (of 60) cases by immunohistochemical and/or molecular analysis, all negative for IDH1 (R132H). Mitotic index ≥ 5/10 HPF and necrosis were associated with decreased overall survival (OS; P = 0.0005 and P = 0.0002, respectively). In all cases except two, necrosis was associated with mitotic index ≥ 5/10 HPF. Patients with BRAF V600E mutant tumors had significantly longer OS compared with those without BRAF V600E mutation (P = 0.02). PXA-AF patients, regardless of age, had significantly shorter OS compared with those without (P = 0.0003). Recurrence-free survival was significantly shorter for adult PXA-AF patients (P = 0.047) only. Patients who either recurred or died ≤ 3 years from diagnosis were more likely to have had either PXA-AF at first diagnosis (P = 0.008) or undergone a non-gross total resection procedure (P = 0.004) as compared with patients who did not. This study provides further evidence that PXA-AF behaves more aggressively than PXA and may qualify for WHO grade III "anaplastic" designation.

Pleomorphic xanthoastrocytomas: institutional experience of 18 patients

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade glioma (World Health Organization Grade II) that most often presents in the first two decades of life. We summarize and present our institutional experience in the management of these tumors. All patients managed for PXA at the University of California San Francisco were retrospectively identified through chart review. Patient demographics, tumor characteristics, management, and follow-up were extracted using medical records. Primary endpoints were overall (OS) and progression-free survival (PFS). In total, nineteen patients were treated for PXA from 1993-2011. Clinical data were available for analysis in 18 patients. Median OS was 209.0 months after date of surgery, with both 5 year and 10 year survival rates of 94%. In this patient cohort, tumor grade (p=0.07), age (p=0.32), and extent of resection (p=0.58) did not predict OS. The majority of tumors (78%) recurred. Median PFS was 21.7 months, with 5 year and 10 year recurrence-free rates of 28% and 22%. On univariate analysis, tumor grade (p=0.01), but not age (p=0.51), size (p=0.30), or extent of resection (p=0.21), was the only covariate predictive of PFS. In patients presenting with higher tumor grade, however, earlier recurrence was demonstrated. Furthermore, the majority of recurrences (36%) occurred within the first 6 months post-operatively, which indicates the need to closely follow patients for that time.

Pleomorphic xanthoastrocytoma arising from olfactory groove: a rare location for a rare tumor

Pleomorphic xanthoastrocytomas (PXAs) are a rare variety of WHO grade II gliomas in children and young adults. The common site of location of PXAs is temporal or cortical. We present a rare case of PXA presenting as anterior cranial fossa (ACF) base lesion. A 7-year-old male presented with a history of a single episode of generalized tonic-clonic seizures and anosmia of 1 year's duration. An MRI of the brain revealed a large solid and cystic tumor in the ACF base with leptomeningeal involvement. The origin of the tumor could not be made out. The patient underwent parasagittal frontal craniotomy and gross total resection of the tumor. The tumor was parenchymal, involving both frontal lobes. It seemed to have been arising from the olfactory groove region. The solid portion of the tumor was also adherent to the falx and basal dura. He recovered completely following surgery. The postoperative period was uneventful. Histopathology was suggestive of PXA with high mitotic index. There was no recurrence of tumor at 6 months' follow-up. He is under close follow-up and will be offered radiotherapy if the tumor recurs. No PXAs arising from this location have been reported previously, and it is important to be aware of this possibility in children presenting with seizures and MRI which shows a solid cystic lesion superficially located in the ACF base region.