A population-based study of the incidence and survival rates in patients with pilocytic astrocytoma

Surgical management of primary and secondary pilocytic astrocytoma of the cerebellopontine angle (in adults and children) and review of the literature

Glial tumors in the cerebellopontine angle (CPA) are uncommon and comprise less than 1% of CPA tumors. We present four cases of pilocytic astrocytoma of the CPA (PA-CPA) that were treated in our department. Patients who received surgical treatment for PA-CPA from January 2004 to December 2019 were identified by a computer search of their files from the Department of Neurosurgery, Tübingen. Patients were evaluated for initial symptoms, pre- and postoperative facial nerve function and cochlear function, complications, and recurrence rate by reviewing surgical reports, patient documents, neuroradiological data, and follow-up data. We identified four patients with PA-CPA out of about 1500 CPA lesions (~ 0.2%), which were surgically treated in our department in the last 16 years. Of the four patients, three were male, and one was a female patient. Two were adults, and two were children (mean age 35 years). A gross total resection was achieved in three cases, and a subtotal resection was attained in one case. Two patients experienced a moderate facial palsy immediately after surgery (House–Brackmann grade III). In all cases, the facial function was intact or good (House–Brackmann grades I–II) at the long-term follow-up (mean follow-up 4.5 years). No mortality occurred during follow-up. Three of the patients had no recurrence at the latest follow-up (mean latest follow-up 4.5 years), while one patient had a slight recurrence. PA-CPA can be safely removed, and most complications immediately after surgery resolve in the long-term follow-up.

A quantitative model based on clinically relevant MRI features differentiates lower grade gliomas and glioblastoma

OBJECTIVES

To establish a quantitative MR model that uses clinically relevant features of tumor location and tumor volume to differentiate lower grade glioma (LRGG, grades II and III) and glioblastoma (GBM, grade IV).

METHODS

We extracted tumor location and tumor volume (enhancing tumor, non-enhancing tumor, peritumor edema) features from 229 The Cancer Genome Atlas (TCGA)-LGG and TCGA-GBM cases. Through two sampling strategies, i.e., institution-based sampling and repeat random sampling (10 times, 70% training set vs 30% validation set), LASSO (least absolute shrinkage and selection operator) regression and nine-machine learning method-based models were established and evaluated.

RESULTS

Principal component analysis of 229 TCGA-LGG and TCGA-GBM cases suggested that the LRGG and GBM cases could be differentiated by extracted features. For nine machine learning methods, stack modeling and support vector machine achieved the highest performance (institution-based sampling validation set, AUC > 0.900, classifier accuracy > 0.790; repeat random sampling, average validation set AUC > 0.930, classifier accuracy > 0.850). For the LASSO method, regression model based on tumor frontal lobe percentage and enhancing and non-enhancing tumor volume achieved the highest performance (institution-based sampling validation set, AUC 0.909, classifier accuracy 0.830). The formula for the best performance of the LASSO model was established.

CONCLUSIONS

Computer-generated, clinically meaningful MRI features of tumor location and component volumes resulted in models with high performance (validation set AUC > 0.900, classifier accuracy > 0.790) to differentiate lower grade glioma and glioblastoma.

KEY POINTS

• Lower grade glioma and glioblastoma have significant different location and component volume distributions. • We built machine learning prediction models that could help accurately differentiate lower grade gliomas and GBM cases. We introduced a fast evaluation model for possible clinical differentiation and further analysis.

Sellar surprises: a single-centre experience of unusual sellar masses

BACKGROUND

Most common incidentally detected sellar-suprasellar region (SSR) masses are pituitary adenomas, followed by craniopharyngioma, rathke's cleft cyst, hypophysitis, and meningioma. Besides these, certain unusual SSR lesions can sometimes present as diagnostic challenges, where diagnosis is often made post-operatively on histopathology, the pre-operative suspicion of which might have influenced the management strategies. Series describing such masses are few.

OBJECTIVE

To present clinical, biochemical, and radiological characteristics and management outcomes of rare SSR lesions other than pituitary adenomas, craniopharyngioma, rathke's cleft cyst, hypophysitis, and meningioma.

DESIGN, SETTING, PATIENTS

Retrospective case record analysis of patients with uncommon SSR masses (from January 2006 to December 2016).

RESULTS

Our series consisted of ten patients, five with neoplastic and five with non-neoplastic lesions. Neoplastic masses included granular cell tumor (n = 2), astrocytoma (n = 1), malignant peripheral nerve sheath tumor (MPNST, n = 1), and metastasis from occult papillary carcinoma of thyroid (n = 1), while non-neoplastic masses were aspergillus abscess (n = 1), sterile abscess (n = 1), and tubercular abscess (n = 1), aneurysm of left internal carotid artery (n = 1), and ruptured dermoid cyst (n = 1). All patients (except one) presented with headache and/or visual disturbance. Only one patient had acromegaly while most others had hypopituitarism. We describe detailed MRI characteristics of each of the lesion. Seven patients underwent trans-sphenoidal surgery. Post-operatively, five patients had permanent diabetes insipidus, while two patients died in early post-operative period.

CONCLUSION

Our series expand the differential diagnostic considerations of SSR lesions. Most of the rare SSR masses present with symptoms of mass effects and hypopituitarism. Except for some non-neoplastic lesions like sellar abscesses, aneurysms, and dermoid cysts which can have some specific imaging characteristics that can provide clue to pre-operative diagnosis, most of the other neoplastic masses have overlapping radiological features, and pre-operative suspicion remains difficult.

Dabrafenib in BRAFV600E mutant pilocytic astrocytoma in a pediatric patient

Pilocytic astrocytomas (PAs) are the most common pediatric central nervous system tumors. They constitute around 30% of all primary central nervous tumors in the pediatric age group. Their clinical behavior may vary but most of them are indolent and do not undergo malignant transformations compared with their adult counterparts. PAs are primarily treated with surgery and in cases of progression; chemotherapy may be needed. They usually carry a good prognosis, with a 10-year survival rate of 90%. BRAFV600E mutations have been identified in approximately 9-15% of patients with PA. These relatively high mutation frequencies in PA open avenues for treatment using targeted therapies such as BRAFV600E inhibitors (e.g., dabrafenib). There have been a few published case reports and case series showing clinical benefits with BRAF inhibitors in BRAF-positive tumors. We report a case of successful treatment of BRAFV600E immunopositive optic pathway PA in a child with dabrafenib.

Audiovestibular findings in a 6 year old child with pilocytic astrocytoma - a case report

Objective: Pilocytic astrocytoma commonly occurs in children and depending on the extension of the lesion may cause varied audiovestibular dysfunctions. However, audiovestibular findings are scarcely reported in the literature.Design: Audiovestibular testing was performed on a single subject on two occasions pre-surgically.Study sample: A 6 year old girl with pilocytic astrocytoma.Results: All audiological tests revealed normal findings except for the cervical vestibular evoked myogenic potential testing (cVEMP). The amplitude of cVEMP was higher in the lesion side indicating a hypersensitive vestibulocollic reflex pathway functioning.Conclusions: This case study reported a unique finding of hypersensitive cVEMP findings in the lesion side in a patient with pilocytic astrocytoma. The pathophysiological basis for this hypersensitivity is attributed to anatomical connections between the cerebellum and the vestibular nuclei through the inferior cerebellar peduncle.

Differentiation of pilocytic and pilomyxoid astrocytomas using dynamic susceptibility contrast perfusion and diffusion weighted imaging

PURPOSE

Pilocytic (PA) and pilomyxoid astrocytomas (PMA) are related low-grade tumors which occur predominantly in children. PMAs have a predilection for a supratentorial location in younger children with worse outcomes. However, the two have similar imaging characteristics. Quantitative MR sequences such as dynamic susceptibility contrast (DSC) perfusion and diffusion (DWI) were assessed for significant differences between the two tumor types and locations.

METHODS

A retrospective search for MRI with DSC and DWI on pathology-proven cases of PMA and PA in children was performed. Tumors were manually segmented on anatomic images registered to rCBV, K2, and ADC maps. Tumors were categorized as PA or PMA, with subclassification of supratentorial and infratentorial locations. Mean values were obtained for tumor groups and locations compared with Student's t test for significant differences with post hoc correction for multiple comparisons. ROC analysis for significant t test values was performed. Histogram evaluation was also performed.

RESULTS

A total of 49 patients met inclusion criteria. This included 30 patients with infratentorial PA, 8 with supratentorial PA, 6 with supratentorial PMA, and 5 with infratentorial PMA. Mean analysis showed significantly increased rCBV for infratentorial PMA (2.39 ± 1.1) vs PA (1.39 ± 0.16, p = 0.0006). ROC analysis for infratentorial PA vs PMA yielded AUC = 0.87 (p < 0.001). Histogram analysis also demonstrated a higher ADC peak location for PMA (1.8 ± 0.2) vs PA (1.56 ± 0.28).

CONCLUSION

PMA has a significantly higher rCBV than PA in the infratentorial space. DSC perfusion and diffusion MR imaging may be helpful to distinguish between the two tumor types in this location.

Predictive measures and outcomes of extent of resection in juvenile pilocytic astrocytoma

PURPOSE

The present study aims to determine the tumor-related, clinical, and demographic factors associated with extent of resection (EOR) and post-operative outcomes in JPA patients.

METHODS

All patients with JPA, identified from a single-center brain tumour data base, were included in this retrospective analysis. Pre-operative MRI scans were reviewed by a single neurosurgeon blinded to the EOR. JPA cases that exhibited no residual tumor post-operatively were assigned to the GTR group, all other tumors were assigned to the <GTR group. Tumor-related, clinical and demographic variables as well as perioperative morbidities were compared between both groups.

RESULTS

Of the 28 patients included, 15 had a GTR (46% male; median age: 7.5 years; range: 1.16-14.9) and 13 had <GTR (69.2% male; median age: 10.6 years; range: 0.66-17.68). Tumor location reached statistical significance, as there were significantly more cerebellar tumors in the GTR group (86.7%) compared to the <GTR group (38.5%) (p = 0.016). GTR cases had a significantly longer average follow-up interval (6.6 months) than <GTR cases (4.5 months) (p = 0.031). All demographic variables, clinical variables and tumor-related factors showed no significant differences between the two groups. There were no differences between GTR and <GTR cases in terms of perioperative outcomes.

CONCLUSIONS

This study shows other than location of the lesion in the cerebellum, demographic, clinical and tumor-related variables are not associated with EOR in children with JPA. GTR was associated with an extended follow-up interval but not with increased perioperative morbidities compared to those with <GTR.

Oncosuppressive Role of RUNX3 in Human Astrocytomas

Background

Gliomas are the most common and aggressive among primary malignant brain tumours with significant inter- and intratumour heterogeneity in histology, molecular profile, and patient outcome. However, molecular targets that could provide reliable diagnostic and prognostic information on this type of cancer are currently unknown. Recent studies show that certain phenotypes of gliomas such as malignancy, resistance to therapy, and relapses are associated with the epigenetic alterations of tumour-specific genes. Runt-related transcription factor 3 (RUNX3) is feasible tumour suppressor gene since its inactivation was shown to be related to carcinogenesis.

Aim

The aim of the study was to elucidate RUNX3 changes in different regulation levels of molecular biology starting from epigenetics to function in particular cases of astrocytic origin tumours of different grade evaluating significance of molecular changes of RUNX3 for patient clinical characteristics as well as evaluate RUNX3 reexpression effect to GBM cells.

Methods

The methylation status and protein expression levels of RUNX3 were measured by methylation-specific PCR and Western blot in 136 and 72 different malignancy grade glioma tissues, respectively. Lipotransfection and MTT were applied for proliferation assessment in U87-MG cells.

Results

We found that RUNX3 was highly methylated and downregulated in GBM. RUNX3 promoter methylation was detected in 69.4% of GBM (n=49) as compared to 0 to 17.2% in I-III grade astrocytomas (n=87). Weighty lower RUNX3 protein level was observed in GMB specimens compared to grade II-III astrocytomas. Correlation test revealed a weak but significant link among Runx3 methylation and protein level. Kaplan-Meier analysis showed that increased RUNX3 methylation and low protein level were both associated with shorter patient survival (p<0.05). Reexpression of RUNX3 in U87-MG cells significantly reduced glioma cell viability compared to control transfection.

Conclusions

The results demonstrate that RUNX3 gene methylation and protein expression downregulation are glioma malignancy dependent and contribute to tumour progression.

Extent of Resection, MGMT Promoter Methylation Status and Tumor Location Independently Predict Progression-Free Survival in Adult Sporadic Pilocytic Astrocytoma

In adults, pilocytic astrocytomas (PA) account for less than 2% of gliomas, resulting in uncertainty regarding the clinical course and optimal treatment, particularly in cases where gross total resection (GTR) could not be achieved. Moreover, information on molecular markers and their prognostic impact is sparse. In order to improve risk stratification, we analyzed our institutional series of 58 patients aged 17 years and older with histology-proven intracranial PA World Health Organization grade I for clinical and molecular prognosticators. Anaplastic and NF1-associated tumors were excluded. O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation status was determined by pyrosequencing or 450k/850k DNA methylation array. A univariate log-rank test and multivariate StepAIC were applied to identify prognostic factors. The median age was 30 years (range 17–66). Tumors were located in the cerebral/cerebellar hemispheres, midline structures and cerebello-pontine angle in 53%, 38% and 9%. MGMT promoter methylation was present in eight patients (14%). GTR (39/58 patients) significantly reduced the likelihood of tumor recurrence (p = 0.0001). Tumor relapse occurred in 16 patients (28%) after a median progression-free survival (PFS) of 135 months (range 6–153 months); there was one tumor-related death. PFS at 5 and 10 years was 67% and 53%. In multivariate analysis, PFS was significantly prolonged in patients with GTR (HR 0.1; CI 0.03–0.37; p < 0.001), unmethylated MGMT promoter (HR 0.18; CI 0.05–0.64; p = 0.009) and midline tumors (HR 0.21; CI 0.06–0.78; p = 0.02). In conclusion, MGMT promoter methylation status and tumor location were identified as novel prognostic factors in adult PAs, pointing at distinct molecular subtypes and detecting patients in need of close observance and intensified treatment.

A Case of Cisternal Pilocytic Astrocytoma Diagnosed with the Balanced Steady-State Free Precession Sequence for Magnetic Resonance Imaging: A Rare Cause of Subarachnoid Hemorrhage

Objectives

In approximately 15% of cases of spontaneous subarachnoid hemorrhage (SAH), an obvious source of bleeding cannot be identified by angiography; these are considered cases of SAH of unknown etiology. A rare case of cisternal pilocytic astrocytoma (PA) presenting with SAH is reported. The usefulness of the balanced steady-state free precession (bSSFP) sequence for magnetic resonance imaging (MRI) to detect small cisternal lesions is discussed.

Case Description

The case of a 73-year-old woman who developed repeated SAHs owing to a cisternal PA is presented. She experienced sudden onset of headache and vomiting, and brain computed tomography showed diffuse SAH, whereas angiography demonstrated normal vasculature. Follow-up imaging, including T1-weighted, T2-weighted, T1-weighted contrast-enhanced, and diffusion-weighted MRI, did not show any parenchymal or cisternal lesions, although computed tomography and fluid-attenuated inversion recovery MRI showed SAH in the same region. In contrast, the bSSFP sequence, taken as a different sequence on the same day, showed mixed-intensity reticular lesions in the left basal cistern, while neither hematoma nor positive findings were identified with the other sequences. Based on the radiologic finding and the repeated history of SAH, the lesions were partially removed 2 weeks after onset. Histological examination showed a PA.

Conclusions

Despite being extremely rare, a small cisternal lesion should be considered as a cause of SAH of unknown etiology. The bSSFP sequence may be useful for detecting cisternal lesions that may be missed on the routine MRI sequences.

Primary spinal pilocytic astrocytoma: clinical study with long-term follow-up in 16 patients and a literature review

Primary pilocytic astrocytoma (PA) of the spine is extremely rare and most published case series only include only a few patients. We attempted to explore the clinical features, radiological findings, and treatment outcomes of patients with spinal PA. Sixteen spinal PA patients who were surgically treated in our hospital between April 2008 and June 2018 were included in this retrospective study. An integrative analysis was performed regarding spinal PA patients by extracting from published studies on PubMed. The 16 patients with spinal PA included eight male and eight female patients with a mean age of 29.1 years. Ten cases (62.5%) had masses located in the cervical segments, five (31.3%) had masses in the thoracic segments, and one (6.2%) had masses in the sacral canal. All the patients were treated surgically with 13 gross total resections (GTRs, 81.3%) and three subtotal resections (STRs). The mean follow-up period was 40.4 months. These tumors accounted for a recurrence rate of 37.5% (6 of 16 patients) and no death during the follow-up periods. The influencing factors of recurrence were mainly STR, gene mutation (NF-1 and H2-K27M), and the number of segments involved. The mean recurrence-free survival duration was 19 months. The imaging features of spinal PA are heterogeneous, and the definitive diagnosis requires pathological support. GTR is the standard therapy for spinal PAs, although patients with GTR are still likely to relapse. The regular spinal magnetic resonance imaging follow-ups are required regardless of the resection status. Reoperation is feasible for patients with recurrence.

Pontine tumor in a neonate: case report and analysis of the current literature

Tumors of the central nervous system represent the largest group of solid tumors found in pediatric patients. Pilocytic astrocytoma is the most common pediatric glioma, mostly located in the posterior fossa. The majority of brainstem tumors, however, are classified as highly aggressive diffuse intrinsic pontine gliomas (DIPGs) and their prognosis is dismal.The authors report on the case of a neonate in whom MRI and neuropathological assessment were used to diagnose DIPG. Before initiation of the planned chemotherapy, the tumor regressed spontaneously, and the newborn exhibited a normal neurological development. Meanwhile, Illumina Human Methylation450 BeadChip analysis reclassified the tumor as pilocytic astrocytoma of the posterior fossa.In conclusion, the authors advocate not initiating immediate intensive therapy in newborns with brain tumors, even with classical appearance of a DIPG; rather, they would like to encourage a biopsy to define the best individual therapeutic approach and avoid ineffective chemotherapy.

Characteristics, survival and incidence rates and trends of pilocytic astrocytoma in children in the United States; SEER-based analysis

INTRODUCTION

Pilocytic astrocytoma (PA) is a neurological neoplasm and a common neurological tumor among children. No recent reports have studied the recent demographic characteristics of PA cases in the US.

METHODOLOGY

We used the Surveillance, Epidemiology, and End Results (SEER) Program to retrieve data on children diagnosed with PA between 2000 and 2015. We calculated the incidence, annual percentage changes (APC), and survival.

RESULTS

Our study included 3084 children with PA, with an incidence of 8.227 per 1,000,000 person-years, being highest among whites (9.062), and children aged 1-4 year (11.175). Overall incidence in children increased significantly over the study period, with an APC of 0.825% (95% CI[0.027-1.630], P = .044). Moreover, incidence among blacks increased significantly over the study period (APC = 3.466%, 95% CI[0.342-6.688], P = .032), but did not change among other races. The relative 5-year survival of included patients was 95.3%, with patients younger than 1 year having the worst survival.

CONCLUSIONS

Overall PA incidence and incidence among blacks has been increasing last decade. Additionally, PA survival was found to be worse among infants. Further studies are also needed to investigate the effect of the age and race on the incidence and survival of PA.

MR imaging features of spinal pilocytic astrocytoma

Background

The purpose of this retrospective review is to determine the MR imaging features of pilocytic astrocytoma (PA) in the spinal cord to help neuroradiologists preoperatively differentiate PA from other intramedullary tumors.

Methods

Neuro-oncology database review revealed 13 consecutive patients with a pathological spinal PA diagnosis and availability of preoperative MR imaging. Three patients had preoperative diffusion-weighted MR imaging. Demographics and conventional and diffusion MR imaging records were retrospectively evaluated.

Results

Among 13 cases of spinal PA, six PAs were located in the cervical region, 4 in the cervical-thoracic region, and 3 in the thoracic region. The average length of vertebral segments involved for the tumors were 4.7 ± 4.6 segments. Six tumors had associated syringomyelia. Eight PAs were located eccentrically in the spinal cord, and eleven had well-defined margins. Eight tumors (61.5%) were intermixed cystic and solid. All were contrast-enhanced, and 53.8% of all PAs showed focal nodule enhancement of the solid components. Two PAs showed intratumoral hemorrhages, and only one demonstrated cap sign. The ADC values (n = 3) of the tumors were 1.40 ± 0.28 × 10^− 3 mm²/s (min–max: 1.17–1.71 × 10^− 3 mm²/s).

Conclusions

PA should be considered in the differential diagnosis of intramedullary tumors that occur in the cervical and thoracic regions. Eccentric growth pattern, well-defined margin, intermixed cystic and solid appearance, focal nodular enhancement of solid components and syringomyelia are relatively frequent features. Relatively high ADC values compared with normal-appearing spinal cord parenchyma are common in spinal PA.

The role of diffusion and perfusion magnetic resonance imaging in differentiation of haemangioblastomas and pilocytic astrocytomas

Purpose

Haemangioblastomas (HABLs) and pilocytic astrocytomas (PAs) are brain tumours presenting similar appearance and location in conventional magnetic resonance (MR) imaging. The purpose of our study was to determine whether a detailed analysis of diffusion (DWI) and perfusion (PWI) characteristics can be useful in preoperative differentiation of these tumours.

Material and methods

The study group consisted of biopsy proven six HABLs and six PAs, which underwent preoperative standard MR examinations including PWI and DWI. In PWI relative cerebral blood volume (rCBV) and the shape of perfusion curves (parameters of peak height - rPH and percentage of signal recovery - rPSR) were analysed. All perfusion parameters were measured for the entire tumour core (mean rCBV, mean rPH, mean rPSR) and in regions with maximal values (max rCBV, max rPH, max rPSR). In DWI parameters of apparent diffusion coefficient (ADC) from the entire tumour core (mean ADC) and in regions with minimal values (min ADC) were evaluated.

Results

Compared to PAs, HABLs presented significantly higher rCBV and rPH values and lower mean rPSR value. PAs showed significantly lower rCBV and rPH values and higher mean rPSR value. Mean rCBV showed no overlap in the values between HABLs and PAs, and thus it provided the highest accuracy in differentiating between them. Max rPSR, mean ADC, and min ADC did not show any significant differences.

Conclusions

High rCBV values and deep perfusion curves with only partial return to the baseline are characteristic features of HABLs differentiating them from PAs, which show lower rCBV values and perfusion curves overshooting the baseline. Diffusion parameters are not useful in differentiation of these tumours.

MicroRNA profile of pediatric pilocytic astrocytomas identifies two tumor-specific signatures when compared to non-neoplastic white matter

PURPOSES

Pilocytic astrocytoma (PA) is a low-grade neoplasm frequently found in childhood. PA is characterized by slow growth and a relatively good prognosis. Genetic mechanisms such as activation of MAPK, BRAF gene deregulation and neurofibromatosis type 1 (NF1) syndrome have been associated with PA development. Epigenetic signature and miRNA expression profile are providing new insights about different types of tumor, including PAs.

METHODS

In the present study we evaluated global miRNA expression in 16 microdissected pediatric PA specimens, three NF1-associated PAs and 11 cerebral white matter (WM) samples by the microarray method. An additional cohort of 20 PAs was used to validate by qRT-PCR the expression of six miRNAs differentially expressed in the microarray data.

RESULTS

Unsupervised hierarchical clustering analysis distinguished one cluster with nine PAs, including all NF1 cases and a second group consisting of the WM samples and seven PAs. Among 88 differentially expressed miRNAs between PAs and WM samples, the most underexpressed ones regulate classical pathways of tumorigenesis, while the most overexpressed miRNAs are related to pathways such as focal adhesion, P53 signaling pathway and gliomagenesis. The PAs/NF1 presented a subset of underexpressed miRNAs, which was also associated with known deregulated pathways in cancer such as cell cycle and hippo pathway.

CONCLUSIONS

In summary, our data demonstrate that PA harbors at least two distinct miRNA signatures, including a subgroup of patients with NF1/PA lesions.

Prenatal and postnatal presentation of PRMT7 related syndrome: Expanding the phenotypic manifestations

Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyze the transfer of methyl groups from S-adenosyl-l-methionine to nitrogen atoms on arginine residues. Arginine methylation is involved in multiple biological processes, such as signal transduction, mRNA splicing, transcriptional control, DNA repair, and protein translocation. Currently, 10 patients have been described with mutations in PRMT7. The shared findings include: hypotonia, intellectual disability, short stature, brachydactyly, and mild dysmorphic features. We describe the prenatal, postnatal, and pathological findings in two male sibs homozygote for a mutation in PRMT7. Both had intrauterine growth restriction involving mainly the long bones. In addition, eye tumor was found in the first patient, and nonspecific brain calcifications and a systemic venous anomaly in the second. The pregnancy of the first child was terminated and we describe the autopsy findings. The second child had postnatal growth restriction of prenatal onset, hypotonia, strabismus, sensorineural hearing loss, genitourinary and skeletal involvement, and global developmental delay. He had dysmorphic features that included frontal bossing, upslanting palpebral fissures, small nose with depressed nasal bridge, and pectus excavatum. Our patients provide additional clinical and pathological data and expand the phenotypic manifestations associated with PRMT7 homozygote/compound heterozygote mutations to include brain calcifications and delayed myelination, and congenital orbital tumor.

Solid non-enhancing cerebellar pilocytic astrocytoma case report

Pilocytic astrocytomas (PA) are slow-growing low-grade gliomas, commonly diagnosed as cerebellar tumors among the pediatric and adolescent population. Characteristic neuroradiologic findings in PA include a cystic mass with enhancing solid nodule. While uncommon radiologic features of PA, including non-enhancing cystic tumors, have been previously described, we present a unique case of a patient with a non-enhancing solid cerebellar PA. The main clinical, radiologic, and pathologic findings are discussed and the relevant literature reviewed. To our knowledge, this is the first reported patient with these radiologic features of PA, highlighting the need for awareness of uncommon presentations when discussing differential diagnosis and pre-operative planning for cerebellar tumors in the relevant age group.

Clinical Significance of T2*gradient-recalled Echo/susceptibility-weighted Imaging Sequences in Evaluating Superficial Siderosis in the Setting of Intracerebral Tumors: Pilocytic Astrocytoma

Superficial siderosis is the slow accumulation of hemosiderin on the pial surfaces of the brain and spinal cord. The most common cause of intracranial superficial siderosis is secondary to subarachnoid hemorrhage. Rarely, superficial siderosis can also be caused by tumors. Superficial siderosis presents clinically as hearing loss and gait instability that progressively worsen. The diagnosis is primarily made by magnetic resonance imaging; however, susceptibility-weighted imaging (SWI) and T2* gradient echo (GRE) sequences demonstrate the highest sensitivity in detecting this condition. To the best of our knowledge, there has been only one previous case of superficial siderosis secondary to a pilocytic astrocytoma of the spine. However, we present a case of intracerebral pilocytic astrocytoma resulting in superficial siderosis, with emphasis on acquisition and use of T2*GRE/SWI sequences.

Primary brain tumours in adults

Primary CNS tumours refer to a heterogeneous group of tumours arising from cells within the CNS, and can be benign or malignant. Malignant primary brain tumours remain among the most difficult cancers to treat, with a 5 year overall survival no greater than 35%. The most common malignant primary brain tumours in adults are gliomas. Recent advances in molecular biology have improved understanding of glioma pathogenesis, and several clinically significant genetic alterations have been described. A number of these (IDH, 1p/19q codeletion, H3 Lys27Met, and RELA-fusion) are now combined with histology in the revised 2016 WHO classification of CNS tumours. It is likely that understanding such molecular alterations will contribute to the diagnosis, grading, and treatment of brain tumours. This progress in genomics, along with significant advances in cancer and CNS immunology, has defined a new era in neuro-oncology and holds promise for diagntic and therapeutic improvement. The challenge at present is to translate these advances into effective treatments. Current efforts are focused on developing molecular targeted therapies, immunotherapies, gene therapies, and novel drug-delivery technologies. Results with single-agent therapies have been disappointing so far, and combination therapies seem to be required to achieve a broad and durable antitumour response. Biomarker-targeted clinical trials could improve efficiencies of therapeutic development.

Anaplastic astrocytoma with piloid features, a novel molecular class of IDH wildtype glioma with recurrent MAPK pathway, CDKN2A/B and ATRX alterations

Tumors with histological features of pilocytic astrocytoma (PA), but with increased mitotic activity and additional high-grade features (particularly microvascular proliferation and palisading necrosis) have often been designated anaplastic pilocytic astrocytomas. The status of these tumors as a separate entity has not yet been conclusively demonstrated and molecular features have only been partially characterized. We performed DNA methylation profiling of 102 histologically defined anaplastic pilocytic astrocytomas. T-distributed stochastic neighbor-embedding (t-SNE) and hierarchical clustering analysis of these 102 cases against 158 reference cases from 12 glioma reference classes revealed that a subset of 83 of these tumors share a common DNA methylation profile that is distinct from the reference classes. These 83 tumors were thus denominated DNA methylation class anaplastic astrocytoma with piloid features (MC AAP). The 19 remaining tumors were distributed amongst the reference classes, with additional testing confirming the molecular diagnosis in most cases. Median age of patients with MC AAP was 41.5 years. The most frequent localization was the posterior fossa (74%). Deletions of CDKN2A/B (66/83, 80%), MAPK pathway gene alterations (49/65, 75%, most frequently affecting NF1, followed by BRAF and FGFR1) and mutations of ATRX or loss of ATRX expression (33/74, 45%) were the most common molecular alterations. All tumors were IDH1/2 wildtype. The MGMT promoter was methylated in 38/83 tumors (45%). Outcome analysis confirmed an unfavorable clinical course in comparison to PA, but better than IDH wildtype glioblastoma. In conclusion, we show that a subset of histologically defined anaplastic pilocytic astrocytomas forms a separate DNA methylation cluster, harbors recurrent alterations in MAPK pathway genes in combination with alterations of CDKN2A/B and ATRX, affects patients who are on average older than those diagnosed with PA and has an intermediate clinical outcome.

Recent Progress in the Pathology and Genetics of Pilocytic and Pilomyxoid Astrocytomas

Pilocytic and pilomyxoid astrocytomas are some of the most common gliomas in children and young adults. These gliomas are indolent neoplasms with long overall survival probability. The genetic characteristics of these neoplasms are well known, and our deepened understanding of their associated molecular alterations has led to the development of novel treatment strategies and approaches. Currently, we can account for some of the unusual behavior, such as oncogene-induced senescence, associated spontaneous regression, anaplastic transformation, and cerebrospinal dissemination, of these gliomas. Nevertheless, enigmatic issues continue to surround these chronic tumors. Here, we review the classical and uncommon clinical pathological and genetic features of these indolent gliomas.

Methylation profiling of paediatric pilocytic astrocytoma reveals variants specifically associated with tumour location and predictive of recurrence

Childhood pilocytic astrocytomas (PA) are low-grade tumours with an excellent prognosis. However, a minority, particularly those in surgically inaccessible locations, have poorer long-term outcome. At present, it is unclear whether anatomical location in isolation, or in combination with underlying biological variation, determines clinical behaviour. Here, we have tested the utility of DNA methylation profiling to inform tumour biology and to predict behaviour in paediatric PA. Genome-wide DNA methylation profiles were generated for 117 paediatric PAs. Using a combination of analyses, we identified DNA methylation variants specific to tumour location and predictive of behaviour. Receiver-operating characteristic analysis was used to test the predictive utility of clinical and/or DNA methylation features to classify tumour behaviour at diagnosis. Unsupervised analysis distinguished three methylation clusters associated with tumour location (cortical, midline and infratentorial). Differential methylation of 5404 sites identified enrichment of genes involved in 'embryonic nervous system development'. Specific hypermethylation of NEUROG1 and NR2E1 was identified as a feature of cortical tumours. A highly accurate method to classify tumours according to behaviour, which combined three clinical features (age, location and extent of resection) and methylation level at a single site, was identified. Our findings show location-specific epigenetic profiles for PAs, potentially reflecting their cell type of origin. This may account for differences in clinical behaviour according to location independent of histopathology. We also defined an accurate method to predict tumour behaviour at diagnosis. This warrants further testing in similar patient cohorts.

Challenges in the management of childhood low-grade glioma in a developing country

BACKGROUND

Treatment modality impacts outcome of childhood low-grade glioma (LGG). Optimizing management in developing countries can be challenging. This study evaluates the clinical characteristics, treatment, and factors influencing outcome of childhood LGG in Saudi Arabia.

PATIENTS AND METHODS

This study retrospectively evaluated 59 children consecutively diagnosed with LGG between January 2001 and June 2016.

RESULTS

Median age at diagnosis was 6.0 years. Pilocytic astrocytoma represented 64.9% of cases. The anatomic site was cerebellar in 23.7%, cerebral in 18.6%, hypothalamic-optic pathway in 33.9%, and midline in 23.7%. The 5-year overall survival (OS) and progression-free survival (PFS) were 90.6 ± 4.7 and 54.3 ± 8.4%, respectively. Initial treatment was observation in 28.8%, surgery alone in 35.6%, chemotherapy in 13.6%, radiotherapy in 5.1%, and combined in 16.9% of cases. The corresponding 5-year PFS was 56.3 ± 15.6, 53.3 ± 14.0, 22.9 ± 19.7, 33.3 ± 27.2, and 88.9 ± 10.5%, respectively (p = 0.006). Among the 61% who had surgical intervention (either alone or in combination with other therapies), 22% achieved complete resection with 5-year radiation/progression-free survival (RPFS) of 87.5 ± 11.7% compared to 27.6 ± 10.8% for subtotal resection/biopsy and 62.2 ± 17.0% for no surgery (p = 0.013). Adjuvant therapy for residual tumor improved survival with 5-year PFS of 66.7 ± 19.2% for chemotherapy and 100% for radiotherapy compared to 12.5 ± 11.4% for observation (p = 0.033).

CONCLUSIONS

We identified variability in the outcomes of LGG. Fewer surgeries with lower rates of total resection were noted, compared to reports from international cooperative groups. The extent of resection was predictive of RPFS. Adjuvant therapy improved the outcome of patients with residual disease, resulting in PFS rates comparable to international data.

Reconstructing the molecular life history of gliomas

At the time of their clinical manifestation, the heterogeneous group of adult and pediatric gliomas carries a wide range of diverse somatic genomic alterations, ranging from somatic single-nucleotide variants to structural chromosomal rearrangements. Somatic abnormalities may have functional consequences, such as a decrease, increase or change in mRNA transcripts, and cells pay a penalty for maintaining them. These abnormalities, therefore, must provide cells with a competitive advantage to become engrained into the glioma genome. Here, we propose a model of gliomagenesis consisting of the following five consecutive phases that glioma cells have traversed prior to clinical manifestation: (I) initial growth; (II) oncogene-induced senescence; (III) stressed growth; (IV) replicative senescence/crisis; (V) immortal growth. We have integrated the findings from a large number of studies in biology and (neuro)oncology and relate somatic alterations and other results discussed in these papers to each of these five phases. Understanding the story that each glioma tells at presentation may ultimately facilitate the design of novel, more effective therapeutic approaches.

Durable response to bevacizumab in adults with recurrent pilocytic astrocytoma

Background:

Adult pilocytic astrocytomas are rare and highly vascular tumors.

Aim:

We hypothesized that they may be uniquely responsive to bevacizumab (BEV).

Patients:

We present four adult patients with pathologically diagnosed WHO grade I pilocytic astrocytoma who had robust and durable responses to BEV at time of recurrence. Three patients developed radiographic changes on MRI, consistent with progressive disease based on response assessment in neuro-oncology criteria. Median time to recurrence was 8.5 months.

Methods:

All patients were treated with six cycles of BEV for recurrence.

Results:

At the end of treatment, all patients had achieved a clinical and radiographic response. Median follow-up time after BEV is 20.5 months.

Conclusion:

This suggests that BEV may have true antitumor activity in adult pilocytic astrocytomas and may be important for achieving durable disease control.

Pediatric cerebellar pilocytic astrocytoma presenting with spontaneous intratumoral hemorrhage

Pilocytic astrocytomas (PAs) are benign glial tumors and one of the most common childhood posterior fossa tumors. Spontaneous intratumoral hemorrhage in PAs occurs occasionally, in about 8-20% of cases. Cerebellar hemorrhages in pediatric population are rare and mainly due to head injuries, rupture of vascular malformations, infections, or hematological diseases. We have investigated the still controversial and unclear pathophysiology underlying intratumoral hemorrhage in PAs. Bleeding in low-grade tumors might be related to structural abnormalities and specific angio-architecture of tumor vessels, such as degenerative mural hyalinization, "glomeruloid" endothelial proliferation, presence of encased micro-aneurysms, and glioma-induced neoangiogenesis. The acute hemorrhagic presentation of cerebellar PA in childhood although extremely uncommon is of critical clinical importance and necessitates promptly treatment. We described a case of hemorrhagic cerebellar PA in a 9-year-old child and reviewed the English-language literature that reported spontaneous hemorrhagic histologically proven cerebellar PA in pediatric patients (0-18 years). According to our analysis, the mortality was not related to symptom onset, tumor location, hemorrhage distribution, presence of acute hydrocephalous, and timing of surgery, while the GCS at hospital admission resulted to be the only statistically significant prognostic factor affecting survival outcome. The abrupt onset of signs and symptoms of acute hydrocephalous and consequent raised intracranial pressure are life-threatening conditions, which need emergent medical and neurosurgical treatments. At a later time, the identification of posterior fossa hemorrhage etiology is crucial to select the appropriate treatment and address the surgical strategy, optimizing the postoperative results.

Promoter methylation of RB1, P15, P16, and MGMT and their impact on the clinical course of pilocytic astrocytomas

Promoter methylation of P15, P16, RB transcriptional corepressor 1 (RB1) and O-6-methylguanine-DNA methyltransferase (MGMT) impacts the prognosis of numerous glioma subtypes. However, whether promoter methylation of these genes also has an impact on the clinical course of pilocytic astrocytoma remains unclear. Using methylation-specific polymerase chain reaction, the methylation status of the tumor suppressor genes P15, P16, RB1, and MGMT in pilocytic astrocytomas (n=18) was analyzed. Immunohistochemical staining for the R132H mutation of the isocitrate dehydrogenase (NADP(+)) 1, cytosolic (IDH1) gene was performed. Clinical data including age, gender, localization of tumor, extent of resection, treatment modality, progression-free survival and overall survival were collected. The methylation index for P15, P16, RB1 and MGMT was 0.0, 0.0, 5.6% (1/18) and 44.5% (8/18), respectively. If the MGMT promoter was methylated, the probability of relapse and second subsequent therapy was significantly increased (P=0.019). The one patient with methylation of P15 demonstrated a poor clinical course. The pilocytic astrocytomas of all 18 patients revealed wild-type IDH1. Clinically, there was a significant correlation of subtotal resection with the occurrence of relapse (P=0.005) and of the localization of the tumor with the extent of resection (P=0.031). Gross total resection was achieved significantly more often in pediatric patients than in adult patients (P=0.003). Adult patients demonstrated more relapses following the first tumor resection (P=0.001). The present study indicates that methylation of MGMT is associated with a poor clinical course and represents an age-independent risk factor for an unfavorable outcome. Other influential factors of outcome were the age of the patient and extent of resection.

Integrated DNA methylation analysis identifies topographical and tumoral biomarkers in pilocytic astrocytomas

Pilocytic astrocytoma (PA) is the most common glioma in pediatric patients and occurs in different locations. Chromosomal alterations are mostly located at chromosome 7q34 comprising the BRAF oncogene with consequent activation of the mitogen-activated protein kinase pathway. Although genetic and epigenetic alterations characterizing PA from different localizations have been reported, the role of epigenetic alterations in PA development is still not clear. The aim of this study was to investigate whether distinctive methylation patterns may define biologically relevant groups of PAs. Integrated DNA methylation analysis was performed on 20 PAs and 4 normal brain samples by Illumina Infinium HumanMethylation27 BeadChips.

We identified distinct methylation profiles characterizing PAs from different locations (infratentorial vs supratentorial) and tumors with onset before and after 3 years of age. These results suggest that PA may be related to the specific brain site where the tumor arises from region-specific cells of origin. We identified and validated in silico the methylation alterations of some CpG islands. Furthermore, we evaluated the expression levels of selected differentially methylated genes and identified two biomarkers, one, IRX2, related to the tumor localization and the other, TOX2, as tumoral biomarker.

Cerebrospinal fluid biomarkers of malignancies located in the central nervous system

CNS malignancies include primary tumors that originate within the CNS as well as secondary tumors that develop as a result of metastatic cancer. The delicate nature of the nervous systems makes tumors located in the CNS notoriously difficult to reach, which poses several problems during diagnosis and treatment. CSF can be acquired relatively easy through lumbar puncture and offers an important compartment for analysis of cells and molecules that carry information about the malignant process. Such techniques have opened up a new field of research focused on the identification of specific biomarkers for several types of CNS malignancies, which may help in diagnosis and monitoring of tumor progression or treatment response. Biomarkers are sought in DNA, (micro)RNA, proteins, exosomes and circulating tumor cells in the CSF. Techniques are rapidly progressing to assess these markers with increasing sensitivity and specificity, and correlations with clinical parameters are being investigated. It is expected that these efforts will, in the near future, yield clinically relevant markers that aid in diagnosis, monitoring and (tailored) treatment of patients bearing CNS tumors. This chapter provides a summary of the current state of affairs of the field of biomarkers of different types of CNS tumors.

A novel GIT2-BRAF fusion in pilocytic astrocytoma

BACKGROUND

KIAA1549-BRAF fusion is the most common genetic event in pilocytic astrocytoma (PA), and leads to activation of the mitogen activated protein kinase (MAPK) signaling pathway. Fusions of BRAF with other partner genes, as well as other genetic alterations not involving BRAF but also leading to MAPK pathway activation have been described rarely.

CASE PRESENTATION

We present a new fusion partner in the low-grade glioma of a 10-year-old male, who presented with headaches and recent episodes of seizures. Magnetic resonance imaging (MRI) demonstrated a right temporal lobe tumor. Histological and immunohistochemical evaluation, and a next generation sequencing assay (Oncopanel, Illumina, 500 genes) including breaKmer analysis for chromosomal rearrangements were performed. Histology was remarkable for a low-grade glioma composed of mildly atypical astrocytes with piloid processes, in a focally microcystic background. Mitoses were not seen; unequivocal Rosenthal fibers or eosinophilic granular bodies were absent. The tumor was positive for OLIG2 and GFAP and negative for BRAF V600E and IDH1 R132H mutant protein immunostains. Oncopanel showed low SOX2 (3q26.33) copy number gain, and no gains at 7q34. There were no significant single nucleotide variants. BreaKmer detected a GIT2-BRAF fusion with loss of BRAF exons 1-8. The integrated diagnosis was low-grade glioma with piloid features, most consistent with pilocytic astrocytoma, WHO grade I.

CONCLUSION

GIT2-BRAF fusion has not been reported in the literature in any tumor. Given that the BRAF sequence deleted is identical to that seen in other fusion events in PA, it most likely acts as tumor driver by activation of the MAPK pathway.

Hemorrhagic presentation of intracranial pilocytic astrocytomas: literature review

Pilocytic astrocytomas (PAs) are seemingly innocuous and benign tumors. However, in recent times, many case series have documented high rates of hemorrhage in these neoplasms. We hereby provide a detailed analysis on hemorrhagic pilocytic astrocytomas (HPA) in adults and report one such case managed at our institute. In addition, salient differences between adult and pediatric hemorrhagic PA have been briefed. Hospital records were retrieved for our case. Literature review was conducted by searching online databases for the following keywords-pilocytic astrocytoma, hemorrhage, cranial, pediatric, and adults. A 22-year-old male with neurofibromatosis-1 presented with sudden onset headache and vomiting of 3-day duration. Imaging revealed a lobulated suprasellar lesion with obstructive hydrocephalus. Pterional transsylvian approach and subtotal resection were performed. Histopathology showed features of PA with bleed. Including current report, a total of 26 cases have been reported. Mean age was 37 years (21-75 years) and they are mostly found in the third decade. The male:female ratio was 2.1:1. Sudden headache with vomiting was the most common symptoms. Tumors were mostly located in cerebral hemispheres (n = 9/34.6%), hypothalamus/suprasellar region (n = 7/27%), and cerebellum (n = 6/23%). Two-thirds underwent gross total excision. There were two deaths and except one case, no recurrences were reported in those with available follow-ups. Hemorrhagic presentation of a PA is rare, although more commonly seen in adults and most commonly located in cerebral hemispheres. Maximal safe resection is the standard treatment and recurrences are rare.

Brainstem pilocytic astrocytoma with H3 K27M mutation: case report

In this report, the authors present the first case of adult brainstem pilocytic astrocytoma (PA) with the H3 K27M mutation. A 53-year-old man was incidentally found to have a 2.5-cm partially enhanced tumor in the tectum on MRI. The enhancement in the lesion increased over 3 years, and gross-total removal was performed via the occipital transtentorial approach. The resected tissue indicated PA, WHO Grade I, and genetic analysis revealed the H3 K27M mutation. However, although the radiological, surgical, and pathological findings all corresponded to PA, this entity can easily be misdiagnosed as diffuse midline glioma with the H3 K27M mutation, which is classified as a WHO Grade IV tumor according to the updated classification. This case highlights the phenotypic spectrum of PA, as well as the biology of the H3 K27M-mutated gliomas, and may prove to be an exception to the rule that diffuse midline gliomas with the H3 K27M mutation behave in an aggressive manner. Based on the findings of this case, the authors conclude that, in addition to detecting the existence of the H3 K27M mutation, an integrated approach in which a combination of clinical, pathological, and genetic information is used should be applied for accurate diagnosis and determination of the appropriate treatment for diffuse midline gliomas.

A new GTF2I-BRAF fusion mediating MAPK pathway activation in pilocytic astrocytoma

Pilocytic astrocytoma (PA) is the most common pediatric brain tumor. A recurrent feature of PA is deregulation of the mitogen activated protein kinase (MAPK) pathway most often through KIAA1549-BRAF fusion, but also by other BRAF- or RAF1-gene fusions and point mutations (e.g. BRAFV600E). These features may serve as diagnostic and prognostic markers, and also facilitate development of targeted therapy. The aims of this study were to characterize the genetic alterations underlying the development of PA in six tumor cases, and evaluate methods for fusion oncogene detection. Using a combined analysis of RNA sequencing and copy number variation data we identified a new BRAF fusion involving the 5’ gene fusion partner GTF2I (7q11.23), not previously described in PA. The new GTF2I-BRAF 19–10 fusion was found in one case, while the other five cases harbored the frequent KIAA1549-BRAF 16–9 fusion gene. Similar to other BRAF fusions, the GTF2I-BRAF fusion retains an intact BRAF kinase domain while the inhibitory N-terminal domain is lost. Functional studies on GTF2I-BRAF showed elevated MAPK pathway activation compared to BRAF^WT. Comparing fusion detection methods, we found Fluorescence in situ hybridization with BRAF break apart probe as the most sensitive method for detection of different BRAF rearrangements (GTF2I-BRAF and KIAA1549-BRAF). Our finding of a new BRAF fusion in PA further emphasis the important role of B-Raf in tumorigenesis of these tumor types. Moreover, the consistency and growing list of BRAF/RAF gene fusions suggests these rearrangements to be informative tumor markers in molecular diagnostics, which could guide future treatment strategies.

Pilocytic Astrocytoma of Fornix Mimicking a Colloid Cyst: Report of 2 Cases and Review of the Literature

BACKGROUND

Colloid cyst is a gelatin-containing cyst in the brain almost always found in the third ventricle. The specific shape and location of these cysts, a round well-delineated mass in the rostral part of the third ventricle adjacent to the foramen of Monro, on imaging are the main findings for diagnosis. Several masses of the third ventricle masquerading colloid cysts on images have been reported. Based on different surgical approaches, preoperative misdiagnosis of colloid cyst may have great impact on prognosis.

METHODS

We report 2 cases that presented with severe headache and hydrocephalus, and their preoperative images were highly indicative of colloid cyst.

RESULTS

Histopathologic investigations after tumor resection showed pilocytic astrocytoma of fornix in both cases.

CONCLUSIONS

Fifteen cases of colloid cyst misdiagnosis with other masses have been reported thus far; among them, 2 cases were pilocytic astrocytoma. In this study we report 2 other cases. Furthermore, we discuss additional clues helping to differentiate pilocytic astrocytoma from colloid cyst on images.

Seizures caused by brain tumors in children

PURPOSE

To review the epidemiology, clinical features, and treatment of seizures secondary to pediatric brain tumors.

METHOD

Literature review.

RESULTS

Pediatric brain tumors are the most common solid pediatric tumor and the most common cause of death in pediatric cancer. Seizures are one of the most common symptoms of pediatric brain tumors. Factors associated with increased risk of seizures include supratentorial location, gray matter involvement, low-grade, and certain histological features-especially dysembryoplastic neuroepithelial tumor, ganglioglioma, and oligodendroglioma. Leukemic infiltration of the brain, brain metastases of solid tumors, and brain injury secondary to chemotherapy or radiotherapy can also cause seizures. Mechanisms by which brain tumors cause seizures include metabolic, and neurotransmitter changes in peritumoral brain, morphologic changes - including malformation of cortical development - in peritumoral brain, and presence of peritumoral blood products, gliosis, and necrosis. As there is a high degree of uncertainty on how effective different antiepileptic drugs are for seizures caused by brain tumors, choices are often driven by the interaction and side effect profile. Classic antiepileptic drugs - phenobarbital, phenytoin, or carbamazepine - should be avoided as they may alter the metabolism of chemotherapeutic agents. Newer drugs - valproate, lamotrigine, topiramate, zonisamide, and levetiracetam - may be the preferred option in patients with tumors because of their very limited interaction with chemotherapy.

CONCLUSION

Seizures are a common presentation of pediatric brain tumors, especially in supratentorial tumors with gray matter involvement. Antiepileptic drug therapy is usually driven by the interaction and side effect profile and newer drugs with few interactions are generally preferred.

NKG2D ligand expression in pediatric brain tumors

Adult brain tumors establish an immunosuppressive tumor microenvironment as a modality of immune escape, with several immunotherapies designed to overcome this barrier. However, the relationship between tumor cells and immune cells in pediatric brain tumor patients is not as well-defined. In this study, we sought to determine whether the model of immune escape observed in adult brain tumors is reflected in patients with pediatric brain tumors by evaluating NKG2D ligand expression on tissue microarrays created from patients with a variety of childhood brain tumor diagnoses, and infiltration of Natural Killer and myeloid cells. We noted a disparity between mRNA and protein expression for the 8 known NKG2D ligands. Surprisingly, high-grade gliomas did not have increased NKG2D ligand expression compared to normal adjacent brain tissue, nor did they have significant myeloid or NK cell infiltration. These data suggest that pediatric brain tumors have reduced NK cell-mediated immune surveillance, and a less immunosuppressive tumor microenvironment as compared to their adult counterparts. These data indicate that therapies aimed to improve NK cell trafficking and functions in pediatric brain tumors may have a greater impact on anti-tumor immune responses and patient survival, with fewer obstacles to overcome.

Suprasellar pilocytic astrocytoma in an adult with hemorrhage and leptomeningeal dissemination: case report and review of literature

Pilocytic astrocytoma (PA) is a low-grade tumor. It has an excellent prognosis after total resection. Leptomeningeal dissemination and hemorrhage are very rare to be associated with PA and lead to unfavorable prognosis. A 35-year-old man was diagnosed with a hemorrhagic suprasellar PA in 2006. Subsequent examination in 2007 revealed another large subdural hemorrhagic lesion in the sacral region, which proved to be PA by histopathologic assessment. Other leptomeningeal foci were discovered mainly at the craniocervical junction. The patient underwent subtotal resection and received chemotherapy with disease control for 7 years. Progression of the disseminated disease has recently occurred; however, the patient is still alive with stable disease after radiotherapy. The radiological features, management, and relevant literature are also presented. Our report heightens the awareness of PA in the adult population and the importance of close surveillance for the leptomeningeal spread, especially for sellar region tumors.

Relative ADC and Location Differ between Posterior Fossa Pilocytic Astrocytomas with and without Gangliocytic Differentiation

BACKGROUND AND PURPOSE

Pilocytic astrocytomas, the most common posterior fossa tumors in children, are characterized by KIAA1549-BRAF fusions and shows excellent 5-year survival rates. Pilocytic astrocytoma with gangliocytic differentiation, a recently defined pilocytic astrocytoma variant that includes glial and neuronal elements similar to a ganglioglioma, may be distinguished from a classic ganglioglioma by molecular, radiologic, and histopathologic features. This study investigated whether imaging could distinguish posterior fossa pilocytic astrocytoma with and without gangliocytic differentiation.

MATERIALS AND METHODS

Preoperative MRIs (± CTs) of 41 children (age range, 7 months to 15 years; mean age, 7.3 ± 3.7 years; 58.5% male) with pilocytic astrocytoma with gangliocytic differentiation (n = 7) or pilocytic astrocytoma (n = 34) were evaluated; differences in tumor location, morphology, and minimum relative ADC between tumor types were compared (Wilcoxon rank sum test, Fisher exact test). Histopathology and BRAF fusion/mutation status were reviewed. Associations of progression-free survival with diagnosis, imaging features, and BRAF status were examined by Cox proportional hazards models.

RESULTS

Pilocytic astrocytoma with gangliocytic differentiation appeared similar to pilocytic astrocytoma but had lower minimum relative ADC (mean, 1.01 ± 0.17 compared with 2.01 ± 0.38 for pilocytic astrocytoma; P = .0005) and was more commonly located within midline structures (P = .0034). BRAF status was similar for both groups. Non-total resection (hazard ratio, 52.64; P = .0002), pilocytic astrocytoma with gangliocytic differentiation diagnosis (hazard ratio, 4.66; P = .0104), and midline involvement (hazard ratio, 3.32; P = .0433) were associated with shorter progression-free survival.

CONCLUSIONS

Minimum relative ADC and tumor location may be useful adjuncts to histopathology in differentiating pilocytic astrocytoma with gangliocytic differentiation from pilocytic astrocytoma. Shorter progression-free survival in pilocytic astrocytoma with gangliocytic differentiation is likely due to a propensity for involvement of midline structures and poor resectability.

Adult anaplastic pilocytic astrocytoma - a diagnostic challenge? A case series and literature review

INTRODUCTION

Anaplastic pilocytic astrocytoma (APA) is an exceptionally rare type of high-grade glioma in adults. Establishing histopathological diagnosis is challenging and its clinical and radiological appearance insidious. By this case series and first literature review we investigated the various clinical, neuroradiological, and histopathological features of APA in adults.

METHODS

An in hospital screening of the database from the Institute of Pathology was conducted to identify cases of APA. Further, we performed a literature review in PubMed using the keywords "anaplastic/malignant/atypical AND pilocytic astrocytoma" and "anaplastic astrocytoma/glioblastoma AND Rosenthal fibers" and summarized the current knowledge about APA in adults.

RESULTS

Over the last decade we were able to identify 3 adult patients with APA in our hospital. According to the pertinent literature, the prognosis of APA in adults (documented survival of up to 10 years) appears to be better than in other high-grade gliomas. Few cases were associated with neurofibromatosis type 1, which seems to predispose for development of APA. Although molecular genetics is still of limited value for differentiation of APA from other high-grade glioma, advanced neuroimaging techniques such as magnetic resonance perfusion imaging and spectroscopy allow improved differential work-up. In particular, APA in adults has the ability to mimic various neurological diseases such as tumefactive demyelinating lesions, low-, or high-grade gliomas.

CONCLUSIONS

Although currently not explicitly recognized as a distinct clinico-pathologic entity it seems that adult APA behaves differently from conventional high-grade glioma and should be included in differential diagnostics to enable adequate patient care. However, further studies are needed to better understand this extremely rare disease.

Hemorrhagic presentations of cerebellar pilocytic astrocytomas in children resulting in death: report of 2 cases

Acute hemorrhagic presentation in pilocytic astrocytomas (PAs) has become increasingly recognized. This type of presentation poses a clinically emergent situation in those hemorrhages arising in PAs of the cerebellum, the most frequent site, because of the limited capacity of the posterior fossa to compensate for mass effect, predisposing to rapid neurological deterioration. As examples, we describe two cases of fatal hemorrhagic cerebellar PAs: one of a child with a slowly growing stereotypical WHO Grade I PA with a 1-year period of symptomatology that preceded a rapid clinical deterioration, and another of an asymptomatic child having a PA variant, presenting with progressive obtundation following a presumed Valsalva event. These two scenarios parallel previous reports in the literature of either a setting of progressive expression of cerebellar dysfunction and transient episodes of raised intracranial pressure (ICP), or abrupt onset of features of increased ICP in a previously well child. The literature is further reviewed for a current understanding of the factors that predispose, initiate and propagate bleeding, with specific reference to the role of vascular endothelial growth factor and other angiogenic agents in the genesis and stability of the vasculature in PAs. In this context, we propose that obliterative vascular mural hyalinization with associated altered flow dynamics and microaneurysm formation was the pathogenesis of the hemorrhage in our first case. In the second case, large tumor size, increased growth rate, looseness of the background myxoid matrix, and thinness of the tumor blood vessels with calcospherite deposition predisposed to vascular leakage and bleeding concurrent with sudden increases in intravascular hydrostatic pressure. In that cerebellar PAs are common, this report underscores the importance of considering in the differential diagnosis the possibility of a spontaneous hemorrhage in a posterior fossa PA in a child presenting with a sudden neurological ictus and raised ICP.

Integrated analysis of DNA methylation profiles and gene expression profiles to identify genes associated with pilocytic astrocytomas

The present study performed an integral analysis of the gene expression and DNA methylation profile of pilocytic astrocytomas (PAs). Weighted gene co-expression network analysis (WGCNA) was also performed to examine and identify the genes correlated to PAs, to identify candidate therapeutic targets for the treatment of PAs. The DNA methylation profile and gene expression profile were downloaded from the Gene Expression Omnibus database. Following screening of the differentially expressed genes (DEGs) and differentially methylated regions (DMRs), respectively, integrated analysis of the DEGs and DMRs was performed to detect their correlation. Subsequently, the WGCNA algorithm was applied to identify the significant modules and construct the co-expression network associated with PAs. Furthermore, Gene Ontology enrichment analysis of the associated genes was performed using the Database for Annotation, Visualization and Integrated Discovery. A total number of 2,259 DEGs and 235 DMRs were screened out. Integrated analysis revealed that 30 DEGs were DMRs with prominent negative correlation (cor=−0.82; P=0.02). Based on the DEGs, the gene co-expression network was constructed, and nine network modules associated with PAs were identified. The functional analysis results showed that genes relevant to PAs were closely associated with cell differentiation modulation. The screened PA-associated genes were significantly different at the expression and methylation levels. These genes may be used as reliable candidate target genes for the treatment of PAs.

Pilocytic astrocytomas

Pilocytic astrocytoma (PA) is the most common pediatric brain tumor in children. PAs are a distinct histologic and biologic subset of glioma that have a slow growth rate and may even spontaneously regress. These tumors tend to arise in the cerebellum and chiasmatic/hypothalamic region, but can also occur in other regions of the central nervous system. Dissemination is uncommon, but may occur in newly diagnosed PAs. Alterations in the Ras/RAF/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway (Ras/ERK) have been discovered in a majority of PAs, with KIAA1549-BRAF fusions being the most commonly identified alteration. Children with neurofibromatosis 1 are predisposed to developing PAs, primarily within the optic pathway. When required, treatment consists of surgery, chemotherapy, and/or radiation, although new molecular agents targeting the Ras/ERK and related signaling pathways are promising new approaches. The 10-year survival rates are greater than 90% in pediatric patients; however, they are poorer in adults. Tumors that are amenable to complete resection (i.e., cerebellum and cortex) have the best overall survival.