Increased mitotic activity as a negative prognostic indicator in pleomorphic xanthoastrocytoma. Case report

Pleomorphic Xanthoastrocytoma: Multi-Institutional Evaluation of Stereotactic Radiosurgery

BACKGROUND AND OBJECTIVES

Pleomorphic xanthoastrocytoma (PXA) is a rare low-grade glial tumor primarily affecting young individuals. Surgery is the primary treatment option; however, managing residual/recurrent tumors remains uncertain. This international multi-institutional study retrospectively assessed the use of stereotactic radiosurgery (SRS) for PXA.

METHODS

A total of 36 PXA patients (53 tumors) treated at 11 institutions between 1996 and 2023 were analyzed. Data included demographics, clinical variables, SRS parameters, tumor control, and clinical outcomes. Kaplan-Meier estimates summarized the local control (LC), progression-free survival, and overall survival (OS). Secondary end points addressed adverse radiation effects and the risk of malignant transformation. Cox regression analysis was used.

RESULTS

A total of 38 tumors were grade 2, and 15 tumors were grade 3. Nine patients underwent initial gross total resection, and 10 received adjuvant therapy. The main reason for SRS was residual tumors (41.5%). The median follow-up was 34 months (range, 2-324 months). LC was achieved in 77.4% of tumors, with 6-month, 1-year, and 2-year LC estimates at 86.7%, 82.3%, and 77.8%, respectively. Younger age at SRS (hazard ratios [HR] 3.164), absence of peritumoral edema (HR 4.685), and higher marginal dose (HR 6.190) were significantly associated with better LC. OS estimates at 1, 2, and 5 years were 86%, 74%, and 49.3%, respectively, with a median OS of 44 months. Four patients died due to disease progression. Radiological adverse radiation effects included edema (n = 8) and hemorrhagic change (n = 1). One grade 3 PXA transformed into glioblastoma 13 months after SRS.

CONCLUSION

SRS offers promising outcomes for PXA management, providing effective LC, reasonable progression-free survival, and minimal adverse events.

Clinical outcomes for pleomorphic xanthoastrocytoma patients

Background

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 2 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 <6 m of follow-up; 15 patients were analyzed (median follow-up 4.4 years). Six patients had grade 2 PXA and 9 had grade 3 anaplastic PXA. The 2- and 5-year PFS for the cohort was 57% and 33%, respectively; 2- 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 = .02. Undergoing a gross total resection was associated with numerical longer survival but this was not of statistical significance (hazard ratio: 0.38, P = .15). All but one (89%) of the grade 3 patients underwent RT.

Conclusions

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.

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.

Long Non-coding RNA and mRNA Co-expression Network Reveals Novel Players in Pleomorphic Xanthoastrocytoma

Histological interpretation of the rare pleomorphic xanthoastrocytoma (PXA) has been the holy grail for treatment options. However, no stand-alone clinical interventions have been developed owing to the lack of gene expression profiling data in PXA/APXA patients. We first time report the comprehensive analyses of the coding as well as long non-coding RNA (lncRNA) signatures of PXA/APXA patients. Several genes such as IGFBP2, NF1, FOS, ERBB2, and lncRNAs such as NEAT1, HOTAIRM1, and GAS5 known to play crucial roles in glioma patients were also deregulated in PXA patients suggesting the commonality in the molecular signatures. PPI network, co-expression, and lncRNA-mRNA interaction studies unraveled hub genes (such as ERBB2, FOS, RPA1) and networks that may play a critical role in PXA biology. The most enriched pathways based on gene profiles were related to TLR, chemokine, MAPK, Rb, and PI3K-Akt signaling pathways. The lncRNA targets were enriched in glucuronidation, adipogenesis, TGF-beta signaling, EGF/EGFR signaling, and cell cycle pathways. Interestingly, several mRNAs like PARVG, and ABI2 were found to be targeted by multiple lncRNAs suggesting a tight control of their levels. Some of the most prominent lncRNA-mRNA pairs were LOC728730: MRPL9, XLOC_l2_011987: ASIC2, lnc-C1QTNF5-1: RNF26. Notably, several lncRNAs such as lnc-CETP-1, lnc-XRCC3-1, lnc-RPL31-1, lnc-USP13-1, and MAPKAPK5-AS1, and genes such as RPA1, NTRK3, and CNRP1 showed strong correlation to the progression-free survival of PXA patients suggesting their potential as novel biomarkers. Overall, the findings of this study may facilitate the development of a new realm of RNA biology in PXA that may have clinical significance in the future.

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.

Malignant transformation of pleomorphic xanthoastrocytoma in pregnant patient: Clinical case and ethical dilemma

Background:

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumor, accounting for <1% of astrocytic tumors. Due to its rarity, etiology, natural history, and biologic behavior is not completely explained. We present a case of malignant transformation of a PXA to glioblastoma in pregnant patient 6 month after tumor biopsy.

Case Description:

A 28-year-old female patient was presented with a newly onset of headache, nausea, and right-sided hemiparesis at 21^st week of pregnancy. Magnetic resonance imaging (MRI) revealed cystic mass in the left frontal region. Patient underwent biopsy to confirm pathohistological analysis; the tumor tissue corresponded to an anaplastic PXA. Two weeks after initial biopsy, open surgery along with gross total tumor removal was performed confirming pathohistological analysis. Six months later, after childbirth, and control MRI revealed a recurrent tumor mass: the patient underwent surgical resection and the tumor tissue corresponded to a glioblastoma. The patients were further treated with radiation and chemotherapy according to oncologist.

Conclusion:

Distinguishing between PXA patients who have a good prognosis and those at risk for early progression is very important for the PXA clinical management. Despite cellular pleomorphism, mitotic index and the extent of resection are shown to be the main predictors for recurrence-free survival and overall survival rates. The standard therapy management is not yet established. Our patient treatment was associated with a significant ethical dilemma. Respecting patient’s wishes to deliver a baby, nor radio or chemo treatments were done. Further studies are necessary to provide factors responsible for malignant transformation of PXA. In addition, in ethically sensitive situation, such as tumor in pregnant patient, good communication, respecting patient’s wishes, and a multidisciplinary teamwork is the key for better outcome.

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.

Pediatric Low-Grade Gliomas

Brain tumors constitute the largest source of oncologic mortality in children and low-grade gliomas are among most common pediatric central nervous system tumors. Pediatric low-grade gliomas differ from their counterparts in the adult population in their histopathology, genetics, and standard of care. Over the past decade, an increasingly detailed understanding of the molecular and genetic characteristics of pediatric brain tumors led to tailored therapy directed by integrated phenotypic and genotypic parameters and the availability of an increasing array of molecular-directed therapies. Advances in neuroimaging, conformal radiation therapy, and conventional chemotherapy further improved treatment outcomes. This article reviews the current classification of pediatric low-grade gliomas, their histopathologic and radiographic features, state-of-the-art surgical and adjuvant therapies, and emerging therapies currently under study in clinical trials.

Cerebellar Pleomorphic Xanthoastrocytoma with BRAF V600E Mutation

BACKGROUND

Pleomorphic xanthoastrocytoma (PXA) is a rare type of astrocytoma with a peak incidence from 10 to 19 years of age. PXA is found most commonly in the supratentorium. When it is present in atypical areas such as the infratentorium, it is often overlooked as a potential differential diagnosis.

CASE DESCRIPTION

This report discusses the case of an 18-year-old woman with a pure PXA in the left cerebellum. The case consists of interesting pathologic and molecular features which do not align with the literature about PXA: a positive finding for BRAF V600E mutation and a negative finding for cluster of differentiation 34 expression. A review of pure PXA cases in the infratentorium has also been completed.

CONCLUSIONS

To our knowledge, this is the first case of PXA in the infratentorium with BRAF V600E mutation. The case also highlights the clinical relevance of including PXA as a differential diagnosis for lesions of the infratentorium.

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.

Demography, Pattern of Care, and Survival in Patients with Xanthoastrocytoma: A Systematic Review and Individual Patient Data Analysis of 325 Cases

Objectives Xanthoastrocytoma (XA) is a low-grade glial tumor seen in young adults and there is lack of robust data on treatment of this rare tumor. In this systematic review and individual patient's data analysis, we aimed to look into the demography, pattern of care, survival outcomes, and prognostic factors in patients with both Grade II and III XA. Methods A comprehensive search was conducted with the Medical Subject Heading terms: "Xanthoastrocytoma; Pleomorphic Xanthoastrocytoma; Anaplastic Xanthoastrocytoma; Xanthoastrocytoma AND treatment; and Anaplastic Xanthoastrocytoma AND survival" to find all possible publications. Results A total of 325 individual patients from a total of 138 publications pertaining to XA were retrieved. Median age of the entire cohort was 19 years. About 56.1% of the patients underwent a gross total resection (GTR) and 31.4% underwent a subtotal resection. Nearly, 76.6% of the patients had a Grade II tumor and adjuvant radiation was delivered in 27.4% of the patients. Estimated 2- and 5-year progression-free survival (PFS) were 68.5 and 51.2%, respectively. Age, grade, and extent of surgery were significant factors affecting PFS. Estimated 2- and 5-year overall survival (OS) was 88.8 and 78%, respectively. The median OS for Grade II and Grade III tumors were 209 and 49 months, respectively. Age and extent of surgery were significant factors affecting OS. Conclusion XA is a disease of young adults with favorable prognosis. Younger patients (<20 years), patients who undergo a GTR, and patients with a lower grade tumor have a better treatment outcome.

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.

Grade II Pleomorphic Xanthoastrocytoma; a meta-analysis of data from previously reported 167 cases

Pleomorphic Xanthoastrocytoma [PXA] is a rare low grade glial tumor commonly affecting young adults. We did this systematic review and meta-analysis to identify prognostic factors and optimal treatment in these patients. A thorough search of the PubMed, Google scholar was made to find all possible publications related to grade II PXA. A total of 167 patients from 89 articles were included in the analysis. Median age of the entire cohort was 20 years. Headache was the most common presentation in 49.1% of the patients followed by seizure in 27.9%. Temporal lobe was the most common location of the tumor. 63% patents underwent a gross total resection [GTR] and 26.7% underwent a sub total excision [STR]. Adjuvant radiation was given to 17.6% of patients. Median follow-up for the entire cohort was 33 months. Estimated median overall survival [OS] for the entire cohort was 209.0 months [96% CI: 149.7-268.3]. Estimated median progression free survival [PFS] was 48 months [95% CI: 31.9-64.0]. In univariate and multivariate analysis younger patients and patients who underwent a GTR had a significantly better survival outcome. Use of adjuvant therapy was not found to be a significant factor affecting PFS or OS. Radiotherapy was used in salvage treatment in 76.1% of the patients. Younger patients and patients who undergo a GTR, have better survival outcomes. There is inadequate evidence to recommend routine adjuvant radiation or chemotherapy in all patients with grade II PXA.

Parieto-temporal pleomorphic xanthoastrocytoma in a black African child

Pleomorphic xanthoastrocytoma (PXA) is a rare cerebral tumor, accounting for <1% of all astrocytic neoplasms. PXA, usually, has a favorable prognosis in spite of what might be suggested from the ominous microscopic appearance. There is no literature immediately available on the black population for this tumor. Management is by surgical resection. The ideal is gross total resection, which offers an excellent prognosis. This disease condition has not been reported in the black population. The following is a presentation of a case report in a black African girl, followed by a review of the literature.

Xantoastrocitoma pleomorfo

Lo xantoastrocitoma pleomorfo è una variante piuttosto rara e relativamente benigna di glioma intracranico che colpisce per lo più soggetti giovani e che mostra una eclatante disparità tra l'aspetto istologico apparentemente maligno e il comportamento clinico invece benevolo.

Dopo la prima descrizione di Kepes et al. nel 1979, 71 casi sono stati riportati nella letteratura principale. Il tumore ha una predilezione per i lobi temporale e parietale ed una localizzazione superficiale con coinvolgimento della corteccia, che rende tecnicamente più facile la sua rimozione radicale; è sempre presente un marcato pleomorfismo cellulare, con la coesistenza di più tipi cellulari, insieme con una risposta positiva alla reazione con l'immunoperossidasi (GFAP) e con l'assenza di necrosi.

La diagnosi pre-operatoria è generalmente difficile. L'iter terapeutico ottimale si fonda sul trattamento chirurgico, eventualmente reiterato in caso di recidiva, cui può associarsi il trattamento radiante.

Pleomorphic Xanthoastrocytoma with Anaplastic Features in the Tectal Region in a Young Adult Patient: A Case Report

BACKGROUND

Pleomorphic xanthoastrocytomas (PXAs) in the tectal region are exceedingly rare and have distinctive clinicopathological features.

CASE PRESENTATION

A 17-year-old man was admitted to our hospital owing to headache and diplopia. Magnetic resonance imaging showed a mass lesion in the tectal gland accompanied by obstructive hydrocephalus. A biopsy and third ventriculostomy were performed. Pathological examination revealed a PXA. Total excision of the lesion was achieved via an occipital transtentorial procedure performed 6 weeks after the biopsy. A pathological examination at that time showed a PXA with anaplastic features and a high mitotic index in surgical specimens. The patient's symptoms improved after the second operation, and radiation and temozolomide-based chemotherapy were administered. No recurrence was found at 24 months after the second operation.

CONCLUSIONS

Maximum resections are recommended in cases with anaplastic features such as a high mitotic index in biopsy specimens because of the likelihood of recurrence and the low overall survival rate. We administered radiotherapy and temozolomide-based chemotherapy because of the high mitotic activity detected in surgical specimens. The postoperative course in this case is currently deemed acceptable.

Aggressive behavior and anaplasia in pleomorphic xanthoastrocytoma: a plea for a revision of the current WHO classification

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm that commonly affects children and young adults, and presents with seizures. PXA is typically supratentorial with a predilection to the temporal lobe, and often involves the cortex and the meninges. PXAs have a favorable prognosis with a 10-year survival probability of >70%, and are WHO grade II neoplasms. Recent observations and studies demonstrate that PXAs are clinically, histologically and genetically distinct. Some PXAs recur and exhibit aggressive clinical behavior. In such cases, certain histological and clinical factors could account for the aggressive behavior. However, the histological features that predict adverse outcome are poorly defined. In the current WHO classification of CNS tumors, there is no option for a high-grade PXA, even if the tumor had numerous recurrences and poor outcome. In this review, we focus on aggressive clinical behavior and anaplasia in PXA, and discuss how our current experience suggests modifications in the current WHO classification. We also review recent discoveries on the molecular characteristics of PXA that could help us better understand their biological behavior.

Does the occurrence of pleomorphic xanthoastrocytoma in the elderly carries a poor prognosis: A case report and review of literature

Pleomorphic xanthoastrocytoma (PXA) is a rare slow growing tumor which accounts for <1% of all astrocytic neoplasms. PXA usually affects young patients in their second decade of life and carries a favorable prognosis. We present the clinical, radiological and histopathological features of PXA involving the left temporal lobe in an 84-year-old male with right upper motor neuron facial paresis of 2 weeks duration. Histopathology confirmed the diagnosis of PXA. Our case is unique in that our patient is the oldest one reported in the literature with favorable histopathological features. The occurrence of these tumors in elderly patients may indicate an aggressive behavior with unfavorable outcome. Gross total resection achieves higher recurrence free and overall survival rates.

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.

Rare primary central nervous system tumors

There are close to 70,000 new cases of primary central nervous system tumors diagnosed annually in the United States. Meningiomas, gliomas, nerve sheath tumors and pituitary tumors account for 85% of them. There is abundant literature on these commonly occurring tumors but data from the literature on infrequently encountered tumors such as atypical teratoid/rhabdoid tumor, choroid plexus carcinoma, ganglioglioma, hemangiopericytoma, and pleomorphic xanthoastrocytoma are limited. This review provides an overview of the clinicopathologic and therapeutic aspects of these rare primary central nervous system tumors.

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.

Epithelioid GBMs show a high percentage of BRAF V600E mutation

BRAF V600E mutation has been identified in up to 2/3 of pleomorphic xanthoastrocytomas (PXAs), World Health Organization grade II, as well as in varying percentages of PXAs with anaplastic features (PXA-A), gangliogliomas, extracerebellar pilocytic astrocytomas, and, rarely, giant cell glioblastoma multiforme (GC-GBMs). GC-GBMs and epithelioid GBMs (E-GBMs) can be histologically challenging to distinguish from PXA-A. We undertook this study specifically to address whether these 2 tumor types also showed the mutation. We tested our originally reported cohort of 8 E-GBMs and 2 rhabdoid GBMs (R-GBM) as well as 5 new E-GBMs (1 pediatric, 4 adult) and 9 GC-GBMs (2 pediatric, 7 adult) (n=24) for BRAF V600E mutational status. Twenty-one of 24 had sufficient material for IDH-1 immunostaining, which is usually absent in PXAs, PXA-As, and primary GBMs but present in secondary GBMs. Patients ranged in age from 4 to 67 years. BRAF V600E mutation was identified in 7/13 of E-GBMs, including 3 of our original cases; patients with mutation were aged 10 to 50 years. None of the 9 GC-GBMs or 2 R-GBMs manifested this mutation, including pediatric patients. The sole secondary E-GBM was the single case manifesting positive IDH-1 immunoreactivity. A high percentage of E-GBMs manifest BRAF V600E mutation, paralleling PXAs. All R-GBMs and GC-GBMs were negative, although larger multi-institutional cohorts will have to be tested to extend this result. BRAF V600E mutational analyses should be performed on E-GBMs, particularly in all pediatric and young-aged adults, given the potential for BRAF inhibitor therapy in this subset of GBM patients.

Prognostic factors and therapeutic outcomes in 22 patients with pleomorphic xanthoastrocytoma

OBJECTIVE

Pleomorphic xanthoastrocytoma (PXA) is a rare primary low-grade astrocytic tumor classified as WHO II. It is generally benign, but disease progression and malignant transformation have been reported. Prognostic factors for PXA and optimal therapies are not well known.

METHODS

The study period was January 2000 to March 2012. Data on MR findings, histology, surgical extents and adjuvant therapies were reviewed in twenty-two patients diagnosed with PXA.

RESULTS

The frequent symptoms of PXA included seizures, headaches and neurologic deficits. Tumors were most common in the temporal lobe followed by frontal, parietal and occipital lobes. One patient who died from immediate post-operative complications was excluded from the statistical analysis. Of the remaining 21 patients, 3 (14%) died and 7 (33%) showed disease progression. Atypical tumor location (p<0.001), peritumoral edema (p=0.022) and large tumor size (p=0.048) were correlated with disease progression, however, Ki-67 index and necrosis were not statistically significant. Disease progression occurred in three (21%) of 14 patients who underwent GTR, compared with 4 (57%) of 7 patients who did not undergo GTR, however, it was not statistically significant. Ten patients received adjuvant radiotherapy and the tumors were controlled in 5 of these patients.

CONCLUSION

The prognosis for PXA is good; in our patients overall survival was 84%, and event-free survival was 59% at 3 years. Atypical tumor location, peritumoral edema and large tumor size are significantly correlated with disease progression. GTR may provide prolonged disease control, and adjuvant radiotherapy may be beneficial, but further study is needed.

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

BACKGROUND

Pleomorphic Xanthoastrocytoma (PXA) is a rare brain tumour, most commonly affecting children and young adults. To date, only few data regarding the long-term follow-up of these patients after surgery are available. The aim of this study is to describe our single-institution experience in the surgical management of this particular glioma over a period of over 18 years.

METHODS

We performed a retrospective review of all cases of PXA (40 patients) operated upon at the Department of Neurosurgery of Verona, Italy, between 1990 and 2008. The impact of clinical, radiological, surgical and histological factors on overall survival (OS) and progression-free survival (PFS) was analysed by means of univariate and multivariate models.

FINDINGS

We achieved a gross total resection (GTR) in 65% of patients. Histological diagnosis was of grade II in 80%; anaplastic features were present in the remaining 20%. Adjuvant treatment, radiotherapy or chemo-radiotherapy, was administered in 40% of the cases. Median follow-up was 74 months. OS at 5- and 10 years was 76.32% and 68.24%, respectively. PFS at 5- and 10 years was 71% and 58%, respectively. In the multivariate model, histological grade, extent of resection and age at diagnosis (≤ 30 years vs > 30 years) were the only independent prognostic factors for both OS and PFS.

CONCLUSIONS

Our retrospective long-term study confirms the relatively favourable prognosis associated with PXA. Young patients with a low-grade tumour (WHO grade II) who underwent GTR carry the longest OS and PFS.

Anaplastic PXA in adults: case series with clinicopathologic and molecular features

Pleomorphic xanthoastrocytomas with anaplastic features (PXA-As) are rare tumors about which little is known regarding clinicopathologic and molecular features. Several studies have identified BRAF V600E mutations in PXA-As, but the percentage with mutation may differ between adult and pediatric examples, and limited information exists about immunohistochemistry for isocitrate dehydrogenase 1 (IDH1). Ten cases of adult PXA-As seen at our institution since 2000 were assessed for BRAF V600E mutation by polymerase chain reaction testing (PCR) and IDH1 by immunohistochemistry. Patients ranged in age from 18-68 years; four PXA-As affected temporal lobe and two were cystic. Four patients underwent gross total resection and 9 of 10 patients received cranial irradiation and/or adjuvant chemotherapy. Five survived less than 5 years, although 2 of 5 patients died from non-tumor causes. Four long-term survivors are alive at 7.5, 9.8, 11.4, and 11.9 years post-diagnosis. Two of four long term survivors had BRAF V600E mutation: patients were ages 18 and 28 years. A 48-year-old male without BRAF mutation survives at 9.8 years, even with thalamic location; conversely a 68-year-old female with temporal lobe tumor and BRAF mutation survived 1.9 years after diagnosis. All tumors were IDH1 immunonegative. This case series details clinicopathologic features of a subset of rare PXA-As in adults. BRAF V600E mutation was identified in 50 % of these cases.

[Pleomorphic xanthoastrocytoma with intraventricular extension and anaplastic transformation in an adult patient: Case report]

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumour that usually occurs in the superficial cerebral hemispheres of children and young adults. Although it has a relatively favourable prognosis, malignant progression of these tumours has been described. Therefore, we present an unusual case of a 54-year-old male with a right, multicystic, parietooccipital tumour extending through the ipsilateral ventricle. After surgical resection, histological examination revealed a lesion with pleomorphic cells, cytoplasmic lipidisation, intensely eosinophilic granular bodies, well-delimitated unique nuclei and focal, positive immunoreactivity for synaptophysin, glial fibrillary acidic protein (GFAP), S-100 protein, vimentin and CD56. Once other tumours, such as giant cell metastatic carcinoma or primary lesion like subependymal giant cell astrocytoma, were ruled out, a final diagnosis of XAP was established. After a follow-up period of 9 months, the patient suffered an extensive and local tumour relapse considered inoperable, with progressive neurological deterioration and radiological findings of malignant progression. The brain biopsy procedure revealed anaplastic changes, including necrosis foci, higher mitotic activity (5×10 high-power fields) and a 10% proliferation index measured by Ki67 labelling. The present case showed intraventricular extension and a more aggressive behaviour, both uncommon in these tumours (similar to anaplastic astrocytoma or glioblastoma multiforme), thus demanding an initial, optimal surgical treatment with close clinical and radiological follow-up, due to the high potential for malignant transformation of XAPs.

Patterns of care and outcomes of patients with pleomorphic xanthoastrocytoma: a SEER analysis

To study the clinical characteristics, treatment approach and outcome of pleomorphic xanthoastrocytoma (PXA), patients were identified using the National Cancer Intitute's Surveillance, Epidemiology, and End Results (SEER) database. A total of 214 patients were identified with PXA using the November 2010 submission. Patient demographics, tumor characteristics, extent of surgical resection, the use of radiotherapy, and overall survival were evaluated. Overall survival for PXA was then compared to that of pilocytic astrocytoma, oligodendroglioma, ependymom and glioblastoma also using the SEER database. Kaplan-Meier, univariate and multivariate analyses were performed. The majority of patients were found to be young adults with the most common tumor location being temporal lobe. Surgery was performed on most (95 %) patients, while 25 % of patients received radiation therapy. Five and 10 year overall survival rates were 75 and 67 %, respectively. Grade was only available for a limited number of patients but appeared to affect prognosis. Patients with grade IV tumors had a median overall survival of 45 months, whereas median survival was not reached for grade I-III patients. On multivariate analysis, male gender and increasing age were associated with worse overall survival (p values 0.05 and <0.006, respectively). Extent of resection trended towards significance in favor of gross total resection. PXA is a rare diagnosis that affects young adults. Surgical resection is the primary modality of treatment with an overall good prognosis. Elderly patients, those with higher grade disease and patients with incomplete resections may have a worse prognosis. The role of radiation therapy for PXA remains unclear but is more often used for patients with high grade tumors. Compared to other common brain tumors, PXA's appear to fare worse than pilocytic astrocytoma and oligodendroglioma, especially in younger patients. However, even high grade PXA patients have significantly better overall survival compared to glioblastoma.

Pleomorphic xanthoastrocytoma with malignant transformation and multiple recurrences in an Iranian girl

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumour of the brain. Some PXAs are accompanied by anaplastic features and are difficult to manage because of frequent recurrences that lead to early death. Well-documented cases of malignant transformation in PXA and of anaplastic PXA are rare in the literature. The authors report a case of PXA with malignant transformation in the right temporo occipital lobe in a 13-year-old Iranian girl.

Malignant potential of pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is a low-grade astrocytic tumour that occasionally progresses to a higher grade. We have extensively reviewed the literature on the potential for malignant transformation of PXA. An illustrative case of a PXA transforming to glioblastoma multiforme is presented.

Pleomorphic xanthoastrocytoma and moyamoya disease in a patient with neurofibromatosis type 1 - case report -

A 32-year-old man with familial neurofibromatosis type 1 presented with a rare case of coexisting pleomorphic xanthoastrocytoma (PXA) and moyamoya disease manifesting as progressive right hemiparesis. Magnetic resonance (MR) imaging with gadolinium showed an enhanced mass lesion in the left basal ganglia extending to the left parietal lobe. Preoperative angiography showed severe stenosis of the bilateral internal carotid arteries, and moyamoya vessels. The patient underwent open biopsy. Histological examination showed the characteristic findings of PXA. After radiation therapy and chemotherapy, MR imaging showed decreased size and enhancement of the tumor, but his clinical condition worsened with generalized convulsions and consciousness disturbance. He died 1 year and 6 months after the first presentation. Autopsy findings demonstrated necrosis in the main mass and tumor cell dissemination without anaplastic change. The rare combination of PXA and moyamoya disease in the basal ganglia limited treatment options. Injured moyamoya vessels and ischemic condition might have caused tumor progression and dissemination. Radiation therapy, in combination with moyamoya disease, induced decreased cerebral blood flow (CBF) in the left frontal lobe. Tumor dissemination, CBF decrease, and hydrocephalus led to the clinical deterioration of this patient.

Pleomorphic xanthoastrocytoma in children and adolescents

BACKGROUND

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumor occurring primarily in children and young adults. The superficial location of the tumor facilitates gross total resection (GTR) thus conferring a relatively favorable outcome with a reported 10-year overall survival (OS) of 70%.

PROCEDURE

A retrospective case analysis of children and adolescents diagnosed and treated with PXA in our institution between January 1980 and March 2009 and a literature review.

RESULTS

85.7% of our patients with a GTR were recurrence free. Only one of seven patients with less than a GTR did not recur and median time to recurrence was under 1 year in patients who did not have a GTR. Two of three patients with anaplastic features or malignant transformation at initial presentation progressed. Five-year OS and recurrence free survival (RFS) was 85.7% and 49%, respectively.

CONCLUSIONS

GTR is the preferred treatment modality for PXA. Anaplastic features, though uncommon at initial presentation, confer a less favorable outcome. The role of adjuvant therapy with primary and recurrent anaplastic PXAs, especially when complete resection is not feasible, warrants further study.

Subtelomeric analysis of pediatric astrocytoma: subchromosomal instability is a distinctive feature of pleomorphic xanthoastrocytoma

Astrocytic neoplasms are genetically heterogeneous; however a low frequency of genomic changes has been found in juvenile pilocytic astrocytoma (PA) in molecular studies. Concerning pleomorphic xanthoastrocytomas (PXA), recent studies have given heterogeneous results for chromosomal alterations. We studied the subtelomeric regions of 19 primary astrocytoma tumors. Results were near normality for the PA group with relative scarcity of chromosomal imbalances, except for the duplication of 3pter in 4/15 and deletion of 21qter in 5/15 of them. In contrast, a specific profile was observed in the 4 PXA tumoral samples. This involved 3pter, 14qter and 19pter duplication and 4qter, 6qter, 9qter, 13cen, 17pter, 18qter and 21qter deletion. Our results indicate that the chromosomal and genetic aberrations in PXAs differed from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences would likely contribute to the more favorable behavior of PXAs and may be helpful for molecular differential diagnosis of pediatric cerebral tumors.

Pleomorphic xanthoastrocytoma: a comparative pathological study between conventional and anaplastic types

AIMS

To facilitate the understanding and correct diagnosis of the anaplastic variant of pleomorphic xanthoastrocytoma (PXA).

METHODS AND RESULTS

Twelve cases of PXA were divided into six conventional and six anaplastic types. Three anaplastic PXAs developed in recurrent tumours and three occurred as the primary tumour. Anaplastic PXAs were microscopically characterized by monotonous proliferation of atypical cells, increased mitotic activity, necrosis and microvascular proliferation. Characteristic features of conventional PXA are also variously included in all anaplastic PXAs. No remarkable differences were detected in the immunohistochemical profiles including the neuronal phenotype between the conventional and anaplastic types. Ki67 labelling indices of the anaplastic type were significantly higher than those of the conventional type, whereas p53 showed no difference. Immunohistochemical and fluorescence in situ hybridization analyses on epidermal growth factor receptor did not demonstrate overexpression or gene amplification.

CONCLUSIONS

The anaplastic PXA, which occurs de novo or through recurrence, should be distinguished from glioblastoma by identifying the salient microscopic features of conventional PXA even in the anaplastic areas; and by demonstrating the expression of neuronal markers, in that the former is expected to have longer survival.

Pleomorphic xanthoastrocytoma in elderly patients may portend a poor prognosis

Pleomorphic xanthoastrocytoma (PXA) is a rare primary astrocytic tumour of the nervous system usually involving the superficial temporal cortex of children and young adults. Although the tumour may exhibit histological features of pleomorphism or cellular atypia, the overall prognosis is good compared with other glial tumours, with only 30% of PXA recurring and 20% undergoing anaplastic transformation. Increased mitotic activity, high MIB-1 and proliferating cell nuclear antigen labelling indices and necrosis are poor prognostic factors, whereas abundant lymphocytic infiltration is associated with more benign biological behaviour. Rarely, in older patients, PXA may have a poor prognosis as these patients tend to have intracranial hypertension and focal deficits, as well as histological features of mitosis, increased cellularity and necrosis. We report the case of a 76-year-old woman who presented with dysphasia and right hemiparesis. A left fronto-temporal lobe PXA was misdiagnosed as glioblastoma multiforme. Although a rare and benign tumour type, PXA in the elderly tend to be more malignant, may have the radiological appearance of a malignant tumour and have poor prognosis.

Cerebellar pleomorphic xanthoastrocytoma: case report and literature review

BACKGROUND

PXA generally has histologic features characteristic of benign biological behavior, although malignant forms have been reported. This neoplasm has also been observed in atypical locations.

METHODS

The authors report a case of cerebellar PXA with rapid malignant transformation in a 58-year-old woman and review the rare presentations and atypical features of this tumor.

RESULTS

Among the "unusual" locations, the most frequent is the cerebellum with 15 cases having been described, 9 in adults, with an average age of 33 years. In contrast, supratentorial forms had a younger age profile (26 years). The time from onset of symptoms to diagnosis was approximately 5.3 months. PXA in the posterior fossa had a higher rate of solid enhancing tumor (9/14). Regarding histologic appearance, two thirds were composite lesions.

CONCLUSIONS

The clinicopathologic features of cerebellar PXA show some differences from PXA located in the cerebral hemispheres. Recognizing the potential for PXA to present with unusual manifestations, regardless of location, has an obvious impact on the accuracy of diagnosis.

MR and CT imaging of 24 pleomorphic xanthoastrocytomas (PXA) and a review of the literature

INTRODUCTION

The aim of our study was to review the imaging appearance of PXA, a rare and usually low-grade, astrocytic tumor that typically occurs in young adults.

METHODS

The clinical presentation, location and imaging findings on CT (n = 15) and MR (n = 18) of 24 pathologically confirmed PXA were retrospectively reviewed. Two morphologic patterns were defined according to imaging features. The Mann-Whitney U-test was used for statistical analysis of the data.

RESULTS

All the neoplasms were supratentorial and superficial in location with obvious leptomeningeal contact in 22 patients, although leptomeningeal enhancement was demonstrated in only 3. Common locations were temporal (42%), frontal (33%) and parietal (21%), and more than one lobe was involved in 21% of patients. On CT without contrast enhancement, PXA was an iso- or hypoattenuating mass, and calcification was seen in six tumors and inner table remodeling was seen in three patients younger than 12 years. On MR, the solid component of PXA was isointense relative to gray matter on T1-weighted images, hyperintense on T2-weighted images in more than 90% and enhanced intensely following intravenous contrast material administration. Cystic areas showed hyperintensity relative to CSF. Two imaging patterns were differentiated: first a cystic mass containing a mural nodule (70%) and second a predominantly solid mass that may show cystic changes (30%).

CONCLUSION

The most consistent imaging features of PXA were a superficial location, leptomeningeal contact, and enhancement of the solid component. Apart from the classical PXA appearance of a cystic lesion with an enhancing mural nodule, a second pattern consisting of a predominantly solid mass was recognized.

Malignant progression in pleomorphic xanthoastrocytoma: Personal experience and review of the literature

Pleomorphic xanthoastrocytoma (PXA) is a rare primary low-grade astrocytic tumor, recently classified as a neuroglial tumor. It generally occurs in children and young adults and shows benign behaviour (WHO II), although an anaplastic variant and malignant potential have been described. Pleomorphic xanthoastrocytomas with malignant transformation have been reported in three out of eight patients operated on for this type of tumor in our department in the last 15 years. The three patients were two adult women and a child, the primary tumors were located in the cortex of the right temporal lobe, and treatment consisted of complete surgical resection. Histological examination revealed simple PXA in two patients and a PXA with anaplastic foci in the other. Mean recurrence time was 5.7 years, with the original xanthoastrocytoma evolving to glioblastoma in two cases and anaplastic astrocytoma in the third. All three patients underwent a second operation, followed by adjuvant therapies. Two died from tumor progression and one from brain edema after intracerebral haemorrhage. A review of the available PXA literature dating back to 1979 revealed 16 cases of primary anaplastic astrocytoma and 21 cases of PXA with malignant transformation. Our experience adds three more cases of malignant transformations, outlining once again the potential malignancy of pleomorphic xanthoastrocytomas and the fact that prognosis in these cases is the same as for primary anaplastic astrocytoma and glioblastoma. Analysis of glioneuronal markers, Ki67 and p53 in all pleomorphic xanthoastrocytomas did not prove to be a discriminating factor to identify a subgroup of xanthoastrocytomas prone to malignancy. Accordingly, these tumors demand close long-term clinical and radiological follow-up.

Pediatric giant cell glioblastoma: a case report and review of the literature

INTRODUCTION

Giant cell glioblastoma is a subtype of glioblastoma multiforme (GM) whose most characteristic histology is the presence of plentiful multinucleated giant cells. These tumours are very rare and account for only 5% of GM. They do not have specific localization, although normally they are supratentorial and affect mostly the temporal lobe. They may occur at any age, but mostly they occur in younger people than GM. They are infrequent in childhood, but they have longer survival in paediatric age.

CASE REPORT

We present an 11-year-old girl that was operated but whose tumour recurred in a month after apparent total removal.

DISCUSSION

We review in the literature the clinical, histological, immuno-histochemical and genetic characteristics, as well the prognosis of this tumour.

Malignant transformation of pleomorphic xanthoastrocytoma

A 31-year-old woman presented with a pleomorphic xantho-astrocytoma (PXA) manifesting as epilepsy. The tumour was partially resected. Histological examination revealed cellular pleomorphism and cytoplasmic vacuolation consistent with PXA, but no mitoses, necrosis, or endothelial proliferation. Follow-up neuro-imaging showed the residual tumour had grown rapidly with dissemination in the spinal cord. The recurrent lesion was totally resected and was shown to be glioblastoma. The patient has survived without signs of recurrence for 36 months after adjuvant radiochemotherapy. The biological behaviour of PXA cannot be predicted based on the histological features and careful follow up is essential.

Coexistence of pleomorphic xanthoastrocytoma with Sturge-Weber syndrome: MRI features

Pleomorphic xanthoastrocytoma is a rare, cortically based, partially cystic astroglial tumour with a strongly enhancing solid mural nodule. We report an 11-year-old boy with a pleomorphic xanthoastrocytoma in the contralateral hemisphere to that affected by Sturge-Weber syndrome. This unique case supports the association between Sturge-Weber syndrome and astrocytomas. Patients with Sturge-Weber syndrome who experience unexpected neurological symptoms should be evaluated with MRI.

Multicentric pleomorphic xanthoastrocytoma in a patient with neurofibromatosis Type 1

✓ The authors report an unusual case of multicentric pleomorphic xanthoastrocytoma (PXA) in a 36-year-old woman with neurofibromatosis Type 1 (NF1). Both lesions were diagnosed as PXA but demonstrated different neuroimaging features and very different outcomes. Although the occipital lesion was cured surgically, the cerebellar tumor recurred three times and underwent malignant transformation into an anaplastic oligodendroglioma.

The authors discuss the causes of PXA and suggest that it could originate from common bipotential precursor cells with two phenotypes.

Prognosis-related histomorphological and immunohistochemical markers in central nervous system tumors of childhood and adolescence

Brain tumors account for approximately 20% of all childhood cancers, and are the leading cause of cancer morbidity and mortality among children. Although numerous demographic, clinical and therapeutic parameters have been identified over the past few years that have significant prognostic bearing for some pediatric brain tumors, predicting the clinical course and outcome among children with central nervous system tumors is still difficult. A survey of publications on prognosis-related histopathological and immunohistochemical features among pediatric brain tumors revealed 172 series, of which 91 presented statistically significant outcome-associated parameters as defined by a P value of less than 0.05. Most investigations revealing significant prognosis-related markers were performed on medulloblastomas (30 publications), ependymomas (25) and astrocytic tumors (18). In total, 16 cohorts consisted of more than 100 cases (5 on ependymomas, 3 each on medulloblastomas and astrocytic tumors). On the other hand, there were also 13 series with fewer than 20 cases (5 on medulloblastomas). Potentially prognostic histopathological markers vary among different entities and consist of assessment of necroses, mitoses, differentiation, vascular proliferation, and growth pattern, whereas immunohistochemical features include proliferation markers (Ki-67, MIB-1), expression of oncogenes/tumor suppressor genes and their proteins (TP53, c-erbB2), growth factor and hormonal receptors (VEGF, EGFR, HER2, HER4, ErbB-2), cell cycle genes (p27, p14ARF) and cell adhesion molecules, as well as factors potentially related to therapeutic resistance (DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the prognostic potential of histopathological and immunohistochemical markers that can be investigated by the practicing neuropathologist as part of the routine diagnostic workload, and scrutinizes their benefit for predicting therapy response and patient outcome among children with brain tumors.

Accumulation of MDM2 in pleomorphic xanthoastrocytomas

The molecular genetic basis and the tumorigenic mechanism of pleomorphic xanthoastrocytoma (PXA) still remain to be elucidated. The amplification of the mdm2 gene and accumulation of the MDM2 protein, which is considered to be one of the major cellular regulators of p53-mediated cell growth control, were studied in eight specimens of PXA obtained from five patients. All of the PXA samples showed at least focal immunopositivity for MDM2. However, none of the samples showed mdm2 gene amplification. These results suggest that accumulation of MDM2 without gene amplification may be one of the major molecular events occurring in the tumorigenesis of PXA.