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

Drug-resistant schizophrenia-like psychosis associated with temporal non-anaplastic pleomorphic xanthoastrocytoma: unusual revealing symptom of a rare pathology

Introduction and importance

Pleomorphic xanthoastrocytoma (PXA) was first described by Kepes et al. in 1979. Fewer than 200 cases have been reported in the literature. It generally involves the temporoparietal lobe. PXA has a favorable prognosis. The most reported clinical manifestation is epileptic seizures. Revealing psychiatric symptoms have an incidence varying from 50 to 78%. The most common symptoms encountered are anxiety disorders, depression, schizophrenia-like psychosis, cognitive dysfunction or even anorexia nervosa.

Case presentation

Here, the authors report a new case of non-anaplastic pleomorphic xanthoastrocytoma revealed by a drug-resistant schizophrenia-like psychosis in a 26-year-old male patient known with epileptic seizures in whom these two pathologies were intertwined and had been evolving for 5 years. The postoperative course was uneventful, and positive symptoms of schizophrenia were relatively stabilized at discharge.

Clinical discussion

Given the superficial hemispheric location of PXA, the most common clinical presentation is seizures. Psychiatric symptoms revealing brain tumors have an incidence varying from 50 to 78%. Most of these symptoms concern frontal and limbal tumors. In their case, the tumor was located in the right temporal lobe. Surgery was performed and postoperative course was uneventful even though there are conflicting reports regarding the importance of the surgical excision quality.

Conclusion

PXA remains a rare and benign primary CNS tumor. Psychiatric disorders represent a rare revealing mode of this pathology, which must lead to neuroimaging in any patient carrying this type of symptoms.

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.

Extra-axial primary meningeal pleomorphic xanthoastrocytoma: a case report

Pleomorphic xanthoastrocytoma (PXA) is a rare low-grade glial neoplasm of the central nervous system accounting for less than 1% of all astrocytomas. Similar to other gliomas, it can rarely arise from glial nests in the meninges, manifesting as an extra-axial mass mimicking a meningioma. Extra axial PXA is an extremely rare entity. Therefore, there are no standardized guidelines. In this article, we report the fourth case, so far, of a solitary primary extra-axial PXA mimicking a meningioma in a 23-year-old woman who presented with temporal seizures and features of raised intracranial pressure. Through this case, we tried to discuss all treatment options.

Nomograms Based on MRI Radiomics for Differential Diagnosis and Predicting BRAFV600E Expression in Pleomorphic Xanthoastrocytoma and Ganglioglioma

RATIONALE AND OBJECTIVES

This study was designed to investigate the value of nomograms based on MRI radiomics and clinical semantic features in identifying pleomorphic xanthoastrocytoma (PXA) and ganglioglioma (GG) as well as predicting BRAFV600E expression.

MATERIALS AND METHODS

This study included 265 patients histologically diagnosed with PXA (n = 113) and GG (n = 152). T1WI, T2WI, and CET1 sequences were utilized to extract radiomics features. Univariate analysis, Spearman correlation analysis, and the least absolute shrinkage and selection operator were used for dimensionality reduction and feature selection. Following this, logistic regression was utilized to establish the radiomics model. Univariate and multivariate analyses of clinical semantic features were applied, and clinical models were constructed. The nomograms were established by merging radiomics and clinical features. Furthermore, ROC curve analysis was used for examining the model performance, whereas the decision curve analysis (DCA) examined the clinical utility of the nomograms.

RESULTS

Nomograms achieved the best predictive efficacy compared to clinical and radiomics models alone. Concerning the differentiation between PXA and GG, the area under the curve (AUC) values of the nomogram were 0.879 (0.828-0.930) and 0.887 (0.805-0.969) for the training and testing cohorts, respectively. For predicting BRAFV600E expression, the AUC values of the nomogram were 0.873 (0.811-0.936) and 0.851 (0.740-0.963) for the training and testing cohorts, respectively. DCA confirmed the clinical utility of the nomograms.

CONCLUSION

Nomograms based on radiomics and clinical semantic features were noninvasive tools for differential diagnosis of PXA and GG and predicting BRAFV600E expression, which may be helpful for assessing patient prognosis and developing individualized treatment strategies.

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.

The 2021 WHO Classification for Gliomas and Implications on Imaging Diagnosis: Part 2-Summary of Imaging Findings on Pediatric-Type Diffuse High-Grade Gliomas, Pediatric-Type Diffuse Low-Grade Gliomas, and Circumscribed Astrocytic Gliomas

The fifth edition of the World Health Organization (WHO) classification of central nervous system tumors published in 2021 advances the role of molecular diagnostics in the classification of gliomas by emphasizing integrated diagnoses based on histopathology and molecular information and grouping tumors based on genetic alterations. This Part 2 review focuses on the molecular diagnostics and imaging findings of pediatric-type diffuse high-grade gliomas, pediatric-type diffuse low-grade gliomas, and circumscribed astrocytic gliomas. Each tumor type in pediatric-type diffuse high-grade glioma mostly harbors a distinct molecular marker. On the other hand, in pediatric-type diffuse low-grade gliomas and circumscribed astrocytic gliomas, molecular diagnostics may be extremely complicated at a glance in the 2021 WHO classification. It is crucial for radiologists to understand the molecular diagnostics and imaging findings and leverage the knowledge in clinical practice. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 3.

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.

Imaging Aspects of the Hippocampus

The hippocampus is one of the most sophisticated structures in the brain, owing to its complex anatomy, intriguing functions, relationship with other structures, and relevant associated symptoms. Despite being a structure analyzed for centuries, its anatomy and physiology in the human body are still being extensively studied, as well as associated pathologic conditions and potential biomarkers. It can be affected by a broad group of diseases that can be classified as congenital, degenerative, infectious or inflammatory, neoplastic, vascular, or toxic-metabolic disease. The authors present the anatomy and close structures, function, and development of the hippocampus, as well as an original algorithm for imaging diagnosis. The algorithm includes pathologic conditions that typically affect the hippocampus and groups them into nodular (space occupying) and nonnodular pathologic conditions, serving as a guide to narrow the differential diagnosis. MRI is the imaging modality of choice for evaluation of the hippocampus, and CT and nuclear medicine also improve the analysis. The MRI differential diagnosis depends on anatomic recognition and careful characterization of associated imaging findings such as volumetric changes, diffusion restriction, cystic appearance, hyperintensity at T1-weighted imaging, enhancement, or calcification, which play a central role in diagnosis along with clinical findings. Some pathologic conditions arising from surrounding structures such as the amygdala are also important to recognize. Pathologic conditions of the hippocampus can be a challenge to diagnose because they usually manifest as similar clinical syndromes, so the imaging findings play a potential role in guiding the final diagnosis. Online supplemental material is available for this article. ^©RSNA, 2022.

Identification of BRAF p. V600E-Mutant and Wild-Type by MR Imaging in Pleomorphic Xanthoastrocytoma and Anaplastic Pleomorphic Xanthoastrocytoma

BACKGROUND AND PURPOSE

Compared with BRAF p. V600E wild-type pleomorphic xanthoastrocytoma, BRAF p. V600E-mutant pleomorphic xanthoastrocytoma showed a higher survival rate. In this study, we focused on finding preoperative MR imaging differences between BRAF p. V600E mutant and wild-type in pleomorphic xanthoastrocytoma and anaplastic pleomorphic xanthoastrocytoma.

MATERIALS AND METHODS

Twenty-three patients with pathologically confirmed pleomorphic xanthoastrocytoma or anaplastic pleomorphic xanthoastrocytoma in our hospital were retrospectively analyzed from January 2015 to December 2020. They were divided into a BRAF p. V600E-mutant group (including 6 pleomorphic xanthoastrocytomas and 5 anaplastic pleomorphic xanthoastrocytomas) and a wild-type group (including 8 pleomorphic xanthoastrocytomas and 4 anaplastic pleomorphic xanthoastrocytomas). The preoperative MR imaging characteristics of these groups were statistically compared.

RESULTS

The wild-type pleomorphic xanthoastrocytoma group presented with more aggressive conventional and advanced MR imaging features than the mutant pleomorphic xanthoastrocytoma group, including greater mean maximum tumor diameter (3.1 [SD, 0.9] cm versus 1.7 [SD, 0.4 ] cm, P < .05), more frequent heterogeneous contrast enhancement of solid portions (100% versus 0%, P < .001), more obvious peritumoral edema (mean, [2.1 SD, 0.7] cm versus 0.6 [SD, 0.2] cm, P < .01), and lower mean minimum relative ADC (896 [SD, 86] versus 988 [SD, 73], P < .05) and mean relative ADC (1060 [SD, 159] versus 1248 [SD, 116], P < .05) on DWI. However, there was no significant difference in either conventional or advanced MR imaging features between the wild-type anaplastic pleomorphic xanthoastrocytoma group and the mutant anaplastic pleomorphic xanthoastrocytoma group.

CONCLUSIONS

Neurosurgeons should carefully interpret MR images before an operation and select appropriate surgical strategies according to genotype prediction.

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

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

Imaging of brain tumors in children: the basics-a narrative review

Primary pediatric brain tumors comprise a broad group of neoplasm subtypes that can be categorized based on their histological and molecular features according to the 2016 World Health Organization (WHO) classification of central nervous system (CNS) tumors. The majority of the pediatric brain tumors demonstrate a singular preference for this age group and have a unique molecular profile. The separation of certain tumor entities, including different types of embryonal tumors, low-grade gliomas, and high-grade gliomas, may have a significant impact by guiding appropriate treatment for these children and potentially changing their outcomes. Currently, the focus of the imaging diagnostic studies is to follow the molecular updates, searching for potential imaging patterns that translate this information in molecular profile results, therefore helping the final diagnosis. Due to the high impact of accurate diagnosis in this context, the scientific community has presented extensive research on imaging pediatric tumors in recent years. This article summarizes the key characteristics of the imaging features of the most common primary childhood brain tumors, categorizing them according to the recent WHO classification update, which is based on each of their molecular profiles. The purpose of this review article is to familiarize radiologists with their key imaging features and thereby improve diagnostic accuracy.

Cerebral pleomorphic xanthoastrocytoma mimicking inflammatory granuloma: Two case reports

RATIONALE

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

PATIENT CONCERNS

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

DIAGNOSIS

After surgical treatment, histopathological examination revealed PXA.

INTERVENTIONS

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

OUTCOMES

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

LESSONS

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

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.

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

BACKGROUND

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

CASE DESCRIPTION

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

CONCLUSIONS

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

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

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

Papillary glioblastoma exhibiting a neuroradiological cyst with a mural nodule: A case report

RATIONALE

Glioblastomas are malignant, infiltrating gliomas classified as grade IV by the World Health Organization. Genetically, most glioblastomas do not exhibit the isocitrate dehydrogenase (IDH) 1/2 gene mutation and rarely harbor the 1p/19q co-deletion. Neuroradiologically, glioblastomas rarely form a cyst with a mural nodule lesion.

PATIENT CONCERNS

In this study, a 78-year-old woman, with speech difficulty and forgetfulness, had a cystic tumor with a mural nodule in the right frontoparietal lobe. Therefore, partial tumor resection was performed.

DIAGNOSIS

Histopathology of the tumor, a glioblastoma, exhibited pseudopapillary features with non-hyalinized capillary cores and rich mini-gemistocytic cells. Genetic analysis of the tumor revealed co-deletion of 1p36/19q13, with wild-type IDH.

INTERVENTIONS

The patient underwent a combination of postoperative radiotherapy and temozolomide chemotherapy before leaving the hospital. After discharge, she was treated by 20 courses of temozolomide chemotherapy.

OUTCOMES

The patient is free from tumor recurrence 23 months after the operation.

LESSONS

We present a unique case of glioblastoma that exhibited novel neuroradiological, histopathological, and genetic features with a favorable prognosis for the patient. Therefore, a compilation of similar cases with clinicopathological and genetic analyses to characterize this unique glioblastoma is critical. Clinical evidence will help develop effective therapeutic approaches to improve prognosis in patients with glioblastoma.

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.

Diagnostic accuracy of diffusion weighted imaging for differentiation of supratentorial pilocytic astrocytoma and pleomorphic xanthoastrocytoma

Purpose

Supratentorial pilocytic astrocytoma (PA) may mimic pleomorphic xanthoastrocytoma (PXA) on conventional MR imaging, and a differentiation is clinically important because of distinct recurrence rate and anaplastic transformation rate. The purpose of this study was to investigate the diagnostic potential of diffusion-weighted imaging (DWI) in differentiating supratentorial PA from PXA.

Methods

We retrospectively reviewed DWI and conventional MR imaging of 16 patients with supratentorial PA and 8 patients with PXA. Variables of mean ADC values (ADC_mean) and minimum ADC values (ADC_min) were calculated from the ROIs containing the contrast-enhancing lesion on DWI. ADC_mean values and ADC_min values were compared among all supratentorial PA and PXA as well as between the subgroup of lobar PA and PXA by using an unpaired Student’s t test. The optimum threshold, sensitivity, specificity, accuracy, and the area under the receiver operating characteristic curve (AUC) were determined.

Results

Both ADC_mean values (1542 ± 186 vs 1084 ± 201 × 10⁻⁶ mm²/s; P < 0.001) and ADC_min values (1355 ± 183 vs 988 ± 180 × 10⁻⁶ mm²/s; P < 0.001) were significantly higher in supratentorial PA compared with PXA. The ADC_mean values and ADC_min values were also significantly higher in lobar PA than those in PXA. The ADC_mean values were useful for differentiating supratentorial PA from PXA, with a threshold value of > 1189.8 × 10⁻⁶ mm²/s (sensitivity, 93.8%; specificity, 100%). The optimal threshold values of > 1189.8 × 10⁻⁶ mm²/s for ADC_mean values provide sensitivity and specificity of 85.7 and 100%, respectively, for discriminating lobar PA from PXA. The optimum threshold value for ADC_min was > 1063.5 × 10⁻⁶ mm²/s.

Conclusion

DWI is helpful in characterization and differentiation of supratentorial PA from PXA.

Electronic supplementary material

The online version of this article (10.1007/s00234-018-2036-y) contains supplementary material, which is available to authorized users.

Pleomorphic Xanthoastrocytoma; Clinicopathological spectrum of An Intriguing neoplasm

Background & Objective:

Pleomorphic xanthoastrocytoma (PXA) is a rare primary WHO Grade II astrocytic tumor comprising of < 1% of all astrocytomas. It is generally benign and slow growing however disease progression and malignant transformation with anaplastic features have been infrequently reported. Our objective was to assess clinicopathological characteristics of this rare tumor at our center.

Methods:

A retrospective study was conducted at Aga Khan University Hospital from January 1992 till January 2016. Data was entered on a proforma including patient demographics, clinical features, tumor location, histological features and follow-up, where available.

Results:

Forty Seven cases of PXA were retrieved during the study period. The mean age was 23.8 years (SD=15.1) and median age was 19 years. The most frequent symptom was head ache (n=31). Male were more frequently affected (n=26). The commonest location was temporal lobe. On microscopic examination, tumors were pleomorphic without mitoses or necrosis, however two cases showed increased mitotic activity, and one case revealed associated gliosarcoma. Follow-up of only 29 cases was available for a period ranging between 2 and 184 months (85 months +/- 56 months). Outcome was good in 27 patients with the last follow up showing no radiographic or clinical evidence of tumor recurrence.

Conclusions:

PXA is an infrequent tumor in our population also, with less than 50 cases identified in two decades study period. Due to its rarity and its bizarre histomorphology, it should be diagnosed correctly, as it has got better prognosis than other astrocytic tumors.

Dabrafenib and trametinib in BRAFV600E mutated glioma

BRAFV600E mutations have been identified in a number of glioma subtypes, most frequently in pleomorphic xanthoastrocytoma, ganglioglioma, pilocytic astrocytoma, and epithelioid glioblastoma. Although the development of BRAF inhibitors has dramatically improved the clinical outcome for patients with BRAFV600E mutant tumors, resistance develops in a majority of patients due to reactivation of the MAPK pathway. Addition of MEK inhibition to BRAF inhibition improves survival. Here we report successful treatment of two patients with BRAFV600E mutant pleomorphic xanthoastrocytoma using the BRAF inhibitor dabrafenib in combination with the MEK inhibitor trametinib.

Adult Brain Tumors and Pseudotumors: Interesting (Bizarre) Cases

Some brain tumors results are interesting due to their rarity at presentation and overwhelming imaging characteristics, posing a diagnostic challenge in the eyes of any experienced neuroradiologist. This article focuses on the most important features regarding epidemiology, location, clinical presentation, histopathology, and imaging findings of cases considered "bizarre." A review of the most recent literature dealing with these unusual tumors and pseudotumors is presented, highlighting key points related to the diagnosis, treatments, outcomes, and differential diagnosis.

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.

Pleomorphic xanthoastrocytoma arising from the suprasellar region: A report of two cases

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm that usually arises in children and young adults. Typically, lesions of PXA are superficially located in the cerebral hemispheres. Herein, we report two extremely rare patients with PXA arising from suprasellar regions. One of the patients is a 29-year-old man admitted to our hospital with a history of progressive headache for 1month. The patient's brain MRI revealed a large tumor arising from the suprasellar cistern of the third ventricle. The second patient, a 52-year-old woman, presented with progressive dizziness and visual disturbance that had developed over the course of 1year. The MRI revealed a well-enhanced suprasellar solid mass measuring 1.4×1.2×1.4cm. Both patients underwent surgical removal of their tumors, and both patients showed similar microscopic structures and immunohistochemical phenotypes: the tumor cells were pleomorphic with mixtures of spindle-shaped, and multinuclear giant cells. In addition, eosinophilic granular bodies and xanthomatous cells were seen on section. Immunohistochemistry was positive for GFAP, S-100, and CD34, and was negative for IDH 1, CK, and Syn. The Ki-67 proliferation index was less than 1%. Silver impregnation revealed reticulin fibers surrounding the individual tumor cells, and small cell groups. Based on these findings, the two patients were diagnosed with PXA in the suprasellar region. To date, only five such patients have been reported in the literature. PXA should be included in the differential diagnosis for tumors arising in the sellar region.

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.

Epilepsy associated tumors: Review article

Long-term epilepsy associated tumors (LEAT) represent a well known cause of focal epilepsies. Glioneuronal tumors are the most frequent histological type consisting of a mixture of glial and neuronal elements and most commonly arising in the temporal lobe. Cortical dysplasia or other neuronal migration abnormalities often coexist. Epilepsy associated with LEAT is generally poorly controlled by antiepileptic drugs while, on the other hand, it is high responsive to surgical treatment. However the best management strategy of tumor-related focal epilepsies remains controversial representing a contemporary issues in epilepsy surgery. Temporo-mesial LEAT have a widespread epileptic network with complex epileptogenic mechanisms. By using an epilepsy surgery oriented strategy LEAT may have an excellent seizure outcome therefore surgical treatment should be offered early, irrespective of pharmacoresistance, avoiding both the consequences of uncontrolled seizures as well as the side effects of prolonged pharmacological therapy and the rare risk of malignant transformation.

Pleomorphic xanthoastrocytoma of childhood: MR imaging and diffusion MR imaging features

BACKGROUND AND PURPOSE

Pleomorphic xanthoastrocytomas are rare astrocytic neoplasms of childhood and young adulthood. The purpose of this retrospective review was to evaluate MR imaging features of pediatric pleomorphic xanthoastrocytomas with an emphasis on diffusion MR imaging.

MATERIALS AND METHODS

Review of the neuro-oncology data base revealed 11 pediatric patients (range, 4.7-16.1 years) with pleomorphic xanthoastroacytomas with 9 of these patients having preoperative MR imaging available. Six patients had preoperative diffusion MR imaging. Demographics, histopathology slides, conventional imaging characteristics (location, cystic component, hemorrhage, enhancement, vasogenic edema, inner table scalloping), and ADC metrics (mean tumor ADC and tumor to normal brain ADC ratio) were evaluated.

RESULTS

Three pleomorphic xanthoastrocytomas had anaplastic features. Ten tumors were supratentorial. Two-thirds (6 of 9) of all tumors were either predominantly cystic or had cystic components, and three-fourths (6 of 8) of the supratentorial tumors had associated inner table scalloping. Seven of the 9 tumors had marked vasogenic edema (>10 mm). Mean tumoral ADC (n = 7) was 912 ± 219 × 10(-6) mm(2)/s (min-max: 617-1189). The tumor to normal brain ADC ratio was 1.14 ± 0.26 (min-max: 0.75-1.47).

CONCLUSIONS

Pleomorphic xanthoastrocytoma should be entertained in the differential diagnosis of peripheral supratentorial tumors that appear during childhood. Cysts, inner table scalloping, and marked vasogenic edema are relatively frequent features. Relatively low ADC values and ADC ratios are not uncommon in pleomorphic xanthoastrocytoma.

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.

Nonanaplastic pleomorphic xanthoastrocytoma with meningeal dissemination presenting with bilateral visual loss

Pleomorphic xanthoastrocytoma (PXA) is a brain neoplasm included in the astrocytic group, exceptionally manifesting with meningeal dissemination. We described a 27-year-old patient presented with acute bilateral visual loss and papilledema with normal brain computed tomography scan, initially mimicking idiopathic intracranial hypertension (IIH). Brain and spinal cord magnetic resonance imaging (MRI) study revealed a subtle area of hyperintensity of the gyri surrounding the left central sulcus, and contrast enhancement of the thoracic leptomeninges. Brain biopsy of the parietal lesion revealed nonanaplastic PXA. Treatment with temozolomide was given. Yearly control MRI demonstrated new brain lesions and marked progression of leptomeningeal spinal enhancement. In spite of this, the patient has remained stable with no new symptoms. Nonanaplastic PXA may present with widespread meningeal dissemination with acute visual loss and papilledema mimicking IIH, and no clinical progression at 3 years.

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.

Pleomorphic xanthoastrocytoma: magnetic resonance imaging findings in a series of cases with histopathological confirmation

Pleomorphic xanthoastrocytoma (PXA) is a rare glioma. This paper aimed to analyze magnetic resonance imaging (MRI) characteristics in a series of patients diagnosed with PXA. We analyzed MRI findings in 9 patients with histopathologic diagnosis of PXA in our department over the last 12 years. The mean age of patients was 27.3 years. Cortical location was observed in all cases. The lesion imaging was solid-cystic in six cases. In eight cases, the solid component presented hypo or isointense on T1 and iso or hyperintense on T2. Contrast enhancement in the solid component was observed in eight cases. The observed imaging pattern of PXA was superficial location with leptomeningeal involvement, solid-cystic pattern and contrast enhancement in the solid component. We should consider that the association between PXA and other cortical tumors may occur, particularly, with gangliogliomas, which tend to be the main differential diagnosis in MRI.

Contrast-enhanced MR imaging in neuroimaging

MR imaging without and with gadolinium-based contrast agents (GBCAs) is an important imaging tool for defining normal anatomy and characteristics of lesions. GBCAs have been used in contrast-enhanced MR imaging in defining and characterizing lesions of the central nervous system for more than 20 years. The combination of unenhanced and GBCA-enhanced MR imaging is the clinical gold standard for the noninvasive detection and delineation of most intracranial and spinal lesions. MR imaging has a high predictive value that rules out neoplasm and most inflammatory and demyelinating processes of the central nervous system.

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

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

Pleomorphic xanthoastrocytoma: MR imaging findings in 19 patients

BACKGROUND

Pleomorphic xanthoastrocytoma (PXA) is a rare and special type of astrocytoma which occurs in childhood and adolescence, and usually with a favorable prognosis. Since its initial description, PXA cases have been reported infrequently in the literature, mostly as single cases or small series.

PURPOSE

To review the imaging characteristics of PXA.

MATERIAL AND METHODS

MR imaging findings of 19 pathologically confirmed PXAs were retrospectively analyzed and correlated with the clinical and pathological features.

RESULTS

The clinical presentation in 18 patients included: dizziness (8); headache (9); and epilepsy (8). One patient was asymptomatic. On MR imaging, the tumors were located in the brain surface (17), thalamus (1) or deep in the right frontal lobe (1). The tumors were cystic (4), mixed cystic-solid (7), or solid (8) with well-defined (11) or poorly-defined borders (8). Peritumoral edema was marked (8), mild (9) or absent (2). Cystic components of tumors were hypointense on T1- and hyperintense on T2-weighted images whereas the solid components of tumors were hypointense or isointense on T1- and slightly hyperintense on T2-weighted images. There was marked (10), moderate (7) or no (2) contrast enhancement in the solid tumors with surrounding leptomeningeal enhancement (7). The tumors were located in the frontal lobes (8), temporal lobes (7), occipital lobe (1), cerebellum (1), thalamus (1), and sellar region (1). Histologically, 18 tumors were classified as WHO grade 2 comprising of pleomorphic giant cells, spindle cells and foamy cells. One PXA with anaplastic features was composed of pleomorphic polygonal cells and spindle cells, and with high mitotic activity ( ≥5 mitoses per 10 HPF). Immunohistochemical reactions to glial fibrillary acidic protein (GFAP) were positive in all 19 cases.

CONCLUSION

The pathological appearances of PXA are distinctive. MR imaging could display the morphologic features exactly, and has important diagnostic value for PXA.

Huge supratentorial extraventricular anaplastic ependymoma presenting with massive calcification--case report

A 15-year-old boy presented with an anaplastic supratentorial ependymoma causing massive intratumoral calcification, without contributory medical and family history, and manifesting as persistent headache for 2 months. Physical examination found no neurological deficit except for visual defect in the right lower quadrant, with intact visual acuity. Blood examination showed no abnormalities. Cranial computed tomography revealed a huge calcified mass in the left parietooccipital lobe, with extensive perilesional brain edema. Cranial radiography showed diffuse and symmetrical thinning of the calvarial bone. Magnetic resonance imaging confirmed the tumor as an assembly of medullated masses with extraventricular location, 7 x 6.5 x 6.5 cm in diameter, and appearing as heterogeneous intensity on both T(1)- and T(2)-weighted images with inhomogeneous enhancement except for the central cores. The patient underwent tumor resection. Intraoperative findings revealed that the cortical veins overlying the tumor were reddish and moderately engorged. The hypervascular tumor, entirely extraventricular in location, was totally resected without neurological deterioration. Histological examination revealed that the tumor was highly cellular with hyperchromatic nuclei and cell atypia. Necrosis, mitotic figures, and perivascular pseudorosette formations were frequently seen. Immunohistochemical study showed positive staining for glial fibrillary acidic protein, S-100 protein, vimentin, and epithelial membrane antigen, but negative for synaptophysin. The MIB-1 labeling index was 26.5%. The findings were compatible with anaplastic ependymoma (World Health Organization classification grade 3). Ependymoma should be included in the differential diagnosis of a supratentorially located, extraventricular mass with massive intratumoral calcification.