Rhabdoid glioblastoma is distinguishable from classical glioblastoma by cytogenetics and molecular genetics

Systematic Review and Individual Patient Data Analysis of Uncommon Variants of Glioblastoma: An Analysis of 196 Cases

OBJECTIVES

Different variant of GBM has been reported viz. Epithelioid Glioblastoma (GBM-E), Rhabdoid GBM (GBM-R), Small cell GBM (GBM-SC), Giant cell GBM (GBM-GC), GBM with neuro ectodermal differentiation (GBM-PNET) with unknown behavior.

MATERIALS

We conducted a systematic review and individual patient data analysis of these rare GBM variants. We searched PubMed, google search, and Cochrane library for eligible studies till July 1^st 2016 published in English language and collected data regarding age, sex, subtype and treatment received, Progression Free Survival (PFS), Overall Survival (OS). Statistical Package for social sciences (SPSS) v16 software was used for all statistical analysis.

RESULTS

We retrieved data of 196 patients with rare GBM subtypes. Among these GBM-GC is commonest (51%), followed by GBM-R (19%), GBM-PNET (13%), GBM-SC (9%) and GBM-E (8%). Median age at diagnosis was 38, 40, 43.5, 69.5 and 18 years, respectively. Male: female ratio was 2:1 for GBM-E, and 1:3 for GBM-SC. Maximal safe resection followed by adjuvant local radiation was used for most of the patients. However, 6 patients with GBM-PNET, 3 each of GBM-E, GBM-SC received adjuvant craniospinal radiation. Out of 88 patients who received chemotherapy, 64 received Temozolomide alone or combination chemotherapy containing Temozolomide. Median PFS and OS for the entire cohort were 9 and 16 months. In univariate analysis, patient with a Gross Total Resection had significantly better PFS and OS compared to those with a Sub Total Resection [23 vs. 13 months (p-0.01)]. Median OS for GBM PNET, GBM-GC, GBM-SC, GBM-R and GBM-E were 32, 18.3, 11, 12 and 7.7 months, respectively (P = 0.001). Interestingly, 31.3%, 37.8% of patients with GBM-E, GBM-R had CSF dissemination.

CONCLUSION

Overall cohort of rarer GBM variant has equivalent survival compared to GBM not otherwise specified. However, epithelioid and Rhabdoid GBM has worst survival and one third shows CSF dissemination.

Diagnostic accuracy of 1p/19q codeletion tests in oligodendroglioma: A comprehensive meta-analysis based on a Cochrane systematic review

Codeletion of chromosomal arms 1p and 19q, in conjunction with a mutation in the isocitrate dehydrogenase 1 or 2 gene, is the molecular diagnostic criterion for oligodendroglioma, IDH mutant and 1p/19q codeleted. 1p/19q codeletion is a diagnostic marker and allows prognostication and prediction of the best drug response within IDH-mutant tumours. We performed a Cochrane review and simple economic analysis to establish the most sensitive, specific and cost-effective techniques for determining 1p/19q codeletion status. Fluorescent in situ hybridisation (FISH) and polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) test methods were considered as reference standard. Most techniques (FISH, chromogenic in situ hybridisation [CISH], PCR, real-time PCR, multiplex ligation-dependent probe amplification [MLPA], single nucleotide polymorphism [SNP] array, comparative genomic hybridisation [CGH], array CGH, next-generation sequencing [NGS], mass spectrometry and NanoString) showed good sensitivity (few false negatives) for detection of 1p/19q codeletions in glioma, irrespective of whether FISH or PCR-based LOH was used as the reference standard. Both NGS and SNP array had a high specificity (fewer false positives) for 1p/19q codeletion when considered against FISH as the reference standard. Our findings suggest that G banding is not a suitable test for 1p/19q analysis. Within these limits, considering cost per diagnosis and using FISH as a reference, MLPA was marginally more cost-effective than other tests, although these economic analyses were limited by the range of available parameters, time horizon and data from multiple healthcare organisations.

Glioblastoma Following Treated Medulloblastoma After 29 Years in the Posterior Fossa: Case Report and Review of Literature

Glioblastoma multiforme (GBM) is a high-grade glioma that may be a rare complication of radiotherapy. We report a case of a patient who was treated for medulloblastoma (MB) of the posterior fossa at the age of 27 years. Twenty-nine years later, at the age of 56 years, he presented with a double-location tumor: supratentorial and in the posterior fossa. Imaging features of the supratentorial location were very suggestive of a meningioma. We operated on the posterior fossa location, which revealed a glioblastoma. Histologically, the tumor cells exhibited characteristics of both GBM and rhabdoid tumor cells. Literature reports of cases of GBM following MB at the same place are very rare, and presenting rhabdoid characteristics is even rarer. This is the first case of MB and GBM at ages 27 and 56 years, respectively. The double-location supratentorial probable meningioma and GBM of the posterior fossa 32 years after MB is the only case reported in the literature. What to do in this case remains a topic of debate, and there are no clear recommendations in the literature.

Diagnostic test accuracy and cost-effectiveness of tests for codeletion of chromosomal arms 1p and 19q in people with glioma

BACKGROUND

Complete deletion of both the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (19q), known as 1p/19q codeletion, is a mutation that can occur in gliomas. It occurs in a type of glioma known as oligodendroglioma and its higher grade counterpart known as anaplastic oligodendroglioma. Detection of 1p/19q codeletion in gliomas is important because, together with another mutation in an enzyme known as isocitrate dehydrogenase, it is needed to make the diagnosis of an oligodendroglioma. Presence of 1p/19q codeletion also informs patient prognosis and prediction of the best drug treatment. The main two tests in use are fluorescent in situ hybridisation (FISH) and polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) assays (also known as PCR-based short tandem repeat or microsatellite analysis). Many other tests are available. None of the tests is perfect, although PCR-based LOH is expected to have very high sensitivity.

OBJECTIVES

To estimate the sensitivity and specificity and cost-effectiveness of different deoxyribonucleic acid (DNA)-based techniques for determining 1p/19q codeletion status in glioma.

SEARCH METHODS

We searched MEDLINE, Embase and BIOSIS up to July 2019. There were no restrictions based on language or date of publication. We sought economic evaluation studies from the results of this search and using the National Health Service Economic Evaluation Database.

SELECTION CRITERIA

We included cross-sectional studies in adults with glioma or any subtype of glioma, presenting raw data or cross-tabulations of two or more DNA-based tests for 1p/19q codeletion. We also sought economic evaluations of these tests.

DATA COLLECTION AND ANALYSIS

We followed procedures outlined in the Cochrane Handbook for Diagnostic Test Accuracy Reviews. Two review authors independently screened titles/abstracts/full texts, performed data extraction, and undertook applicability and risk of bias assessments using QUADAS-2. Meta-analyses used the hierarchical summary ROC model to estimate and compare test accuracy. We used FISH and PCR-based LOH as alternate reference standards to examine how tests compared with those in common use, and conducted a latent class analysis comparing FISH and PCR-based LOH. We constructed an economic model to evaluate cost-effectiveness.

MAIN RESULTS

We included 53 studies examining: PCR-based LOH, FISH, single nucleotide polymorphism (SNP) array, next-generation sequencing (NGS), comparative genomic hybridisation (CGH), array comparative genomic hybridisation (aCGH), multiplex-ligation-dependent probe amplification (MLPA), real-time PCR, chromogenic in situ hybridisation (CISH), mass spectrometry (MS), restriction fragment length polymorphism (RFLP) analysis, G-banding, methylation array and NanoString. Risk of bias was low for only one study; most gave us concerns about how patients were selected or about missing data. We had applicability concerns about many of the studies because only patients with specific subtypes of glioma were included. 1520 participants contributed to analyses using FISH as the reference, 1304 participants to analyses involving PCR-based LOH as the reference and 262 participants to analyses of comparisons between methods from studies not including FISH or PCR-based LOH. Most evidence was available for comparison of FISH with PCR-based LOH (15 studies, 915 participants): PCR-based LOH detected 94% of FISH-determined codeletions (95% credible interval (CrI) 83% to 98%) and FISH detected 91% of codeletions determined by PCR-based LOH (CrI 78% to 97%). Of tumours determined not to have a deletion by FISH, 94% (CrI 87% to 98%) had a deletion detected by PCR-based LOH, and of those determined not to have a deletion by PCR-based LOH, 96% (CrI 90% to 99%) had a deletion detected by FISH. The latent class analysis suggested that PCR-based LOH may be slightly more accurate than FISH. Most other techniques appeared to have high sensitivity (i.e. produced few false-negative results) for detection of 1p/19q codeletion when either FISH or PCR-based LOH was considered as the reference standard, although there was limited evidence. There was some indication of differences in specificity (false-positive rate) with some techniques. Both NGS and SNP array had high specificity when considered against FISH as the reference standard (NGS: 6 studies, 243 participants; SNP: 6 studies, 111 participants), although we rated certainty in the evidence as low or very low. NGS and SNP array also had high specificity when PCR-based LOH was considered the reference standard, although with much more uncertainty as these results were based on fewer studies (just one study with 49 participants for NGS and two studies with 33 participants for SNP array). G-banding had low sensitivity and specificity when PCR-based LOH was the reference standard. Although MS had very high sensitivity and specificity when both FISH and PCR-based LOH were considered the reference standard, these results were based on only one study with a small number of participants. Real-time PCR also showed high specificity with FISH as a reference standard, although there were only two studies including 40 participants. We found no relevant economic evaluations. Our economic model using FISH as the reference standard suggested that the resource-optimising test depends on which measure of diagnostic accuracy is most important. With FISH as the reference standard, MLPA is likely to be cost-effective if society was willing to pay GBP 1000 or less for a true positive detected. However, as the value placed on a true positive increased, CISH was most cost-effective. Findings differed when the outcome measure changed to either true negative detected or correct diagnosis. When PCR-based LOH was used as the reference standard, MLPA was likely to be cost-effective for all measures of diagnostic accuracy at lower threshold values for willingness to pay. However, as the threshold values increased, none of the tests were clearly more likely to be considered cost-effective.

AUTHORS' CONCLUSIONS

In our review, most techniques (except G-banding) appeared to have good sensitivity (few false negatives) for detection of 1p/19q codeletions in glioma against both FISH and PCR-based LOH as a reference standard. However, we judged the certainty of the evidence low or very low for all the tests. There are possible differences in specificity, with both NGS and SNP array having high specificity (fewer false positives) for 1p/19q codeletion when considered against FISH as the reference standard. The economic analysis should be interpreted with caution due to the small number of studies.

Predicting BRAF V600E mutation in glioblastoma: utility of radiographic features

Detection of BRAF V600E mutation in glioblastomas (GBMs) is important because of potential therapeutic implications. Still, the relative paucity of these mutations makes molecular detection in all GBMs controversial. In the present study, we analyzed clinical, radiographic and pathologic features of 12 BRAF V600E-mutant GBMs and 12 matched controls from 2 institutions. We found that a majority of BRAF V600E-mutant GBMs displayed a combination of well-circumscribed lesions, large cystic components with thin walls and solid cortical component on MRI, but with some overlap with matched BRAF wildtype controls (p = 0.069). BRAF V600E-mutant GBMs were also apt to gross total resection (83% vs 17%, p = 0.016) and morphologically displayed epithelioid features (83% vs 0%, p < 0.0001). Identification of these clinical, radiographic, and pathologic characteristics should prompt testing for BRAF V600E in IDH-wildtype GBM.

Fulminant presentation of a SMARCB1-deficient, anterior cranial fossa tumor in adult

Background:

Malignant atypical teratoid rhabdoid tumor (ATRT) usually develops in children. ATRTs are rare in adults, with only one case in the literature describing involvement of the anterior skull base. These primary intracranial tumors are characterized molecularly as SMARCB1 (INI1) deficient. Different types of such SMARCB1-deficient tumors exist in adulthood, usually in the form of extracranial tumors. Very few cases of such a new entity, named SMARCB1-deficient sinonasal carcinoma have been described with intracranial penetration and involvement of the anterior cranial fossa.

Case Description:

A 36-year-old male presented with acute cognitive deterioration. Over few hours, he developed a fulminant herniation syndrome. Imaging showed a tumor in the anterior cranial fossa surrounded by massive brain edema. The tumor has destroyed the frontal bone with involvement of the nasal cavities and paranasal sinuses. The patient underwent emergent decompressive craniectomy and tumor debulking but could not be saved. Pathological analysis revealed a highly cellular tumor without rhabdoid cells but with areas of necrosis. Further immunohistochemical stains revealed that neoplastic cells were diffusely and strongly positive for epithelial membrane antigen and P63 and negative for SMARCB1 (i.e., loss of expression), confirming the diagnosis of sinonasal carcinoma.

Conclusion:

To the best of our knowledge, this is the first report of a fulminant presentation of a SMARCB1- deficient tumor in young adult, involving the anterior cranial fossa and the paranasal sinuses. The main differential diagnosis of aggressive, primary, intracranial SMARCB1-deficient tumors in adults includes ATRT, SMARCB1- deficient sinonasal carcinoma, rhabdoid meningioma, and rhabdoid glioblastoma. Atypical tumors involving the anterior skull base without a clear histopathological pattern should therefore be checked for SMARCB1 expression.

Advances in Diagnostic Immunohistochemistry for Primary Tumors of the Central Nervous System

As genomic characterization becomes increasingly necessary for accurate diagnosis of tumors of the central nervous system, identification of rapidly assessible biomarkers is equally important to avoid excessive cost and delay in initiation of therapy. This article reviews novel immunohistochemical markers that may be used to determine mutation status, activation of signaling pathways, druggable targets, and cell lineage in many diverse tumor types. In particular, recently added entities to the 2016 WHO classification of central nervous system tumors will be addressed, including IDH-mutant gliomas, diffuse midline glioma, epithelioid glioblastoma, angiocentric glioma, RELA-rearranged ependymoma, embryonal tumors (medulloblastoma, atypical teratoid/rhabdoid tumor, pineoblastoma, embryonal tumor with multilayered rosettes, and other genetically defined high-grade neuroepithelial tumors), and meningiomas associated with germline alterations.

Confirming Diagnosis and Effective Treatment for Rare Epithelioid Glioblastoma Variant: An Integrated Survival Analysis of the Literature

BACKGROUND

Epithelioid glioblastoma (eGBM) is a very rare histologic variant of glioblastoma that has not been studied in isolation and, therefore, its optimal management has been largely assumed, but not confirmed. The aim of this study was to analyze all reported cases describing the presentation and clinical features to better understand the clinical significance of this histologic diagnosis.

METHODS

A comprehensive literature search was conducted from 2005 to April 2019 identifying cases of eGBM that satisfied selection criteria for analysis. Survival was investigated using Kaplan-Meier estimations, and then univariate and multivariate logistic regression analyses for primary end point overall survival (OS) and second end point progression-free survival (PFS).

RESULTS

A total cohort of 59 eGBM cases from 28 articles were included for final analysis. Median age of patients at diagnosis was 30 years, with 29 (46%) female patients. When reported, 100% (37/37) cases were IDH1-wild-type and 63% (19/30) were positive for the BRAF V600E mutation by immunohistochemistry. Median OS and PFS were estimated to be 11.0 months (95% confidence interval, 6.5-13.0) and 7.0 months (95% confidence interval, 3.0-10.0), respectively. Surgical extent of resection, radiation therapy, and chemotherapy all predicted superior OS and PFS on multivariate analysis (P < 0.05). No biomarkers prognosticated survival.

CONCLUSIONS

These findings indicate that the histologic diagnosis of eGBM does not deviate from the clinical course of the broader glioblastoma diagnosis, despite being a unique histologic identity. These results argue against the temptation to deviate from the traditional management paradigm of surgery, radiation, and chemotherapy for glioblastoma based on this histology alone.

Radiation-induced glioblastoma with rhabdoid characteristics following treatment for medulloblastoma: A case report and review of the literature

Glioblastoma multiforme (GBM) is a high-grade glioma that may develop from several other central nervous system tumors after radiation therapy. We herein report a case of GBM occurring 8 years after radiation therapy for medulloblastoma. The secondary tumor was histologically distinctly different from the primary tumor. Previously reported cases indicate that GBM induced by radiation therapy is associated with a highly aggressive clinical course with a high risk of early recurrence and poor prognosis. In addition, histological examination revealed that the tumor cells exhibited characteristics of both GBM and rhabdoid tumor cells. The diverse pathological characteristics of GBM may reflect the potential effects of radiation therapy on the tumor.

Atypical teratoid rhabdoid tumor involving the nasal cavities and anterior skull base

Rhabdoid tumors are a spectrum of neoplasias composed of cells which show rhabdoid morphology but are devoid of skeletal muscle differentiation. These tumors are characterized by inactivation of the INI1/SMARCB1 gene and they have been described in virtually every anatomical site, including the central nervous system (CNS) and sinonasal tract. Rhabdoid tumor of the CNS was named atypical teratoid rhabdoid tumor (ATRT) and it mainly affects children under the age of 3 years with supra- or infra-tentorial location.Herein we report the first case of ATRT infiltrating the nasal cavities and skull base in an adolescent. Due to its unusual location, differential diagnosis was challenging and included several other entities such as sinonasal carcinoma or meningioma. Awareness that ATRT may infiltrate the nasal tract and knowledge of its clinico-pathological, immunohistochemical and biomolecular features are essential for its distinction from other rhabdoid tumors which more frequently involve this anatomical site and for appropriate therapeutic management.

Detection of a Distinctive Genomic Signature in Rhabdoid Glioblastoma, A Rare Disease Entity Identified by Whole Exome Sequencing and Whole Transcriptome Sequencing

We analyzed the genome of a rhabdoid glioblastoma (R-GBM) tumor, a very rare variant of GBM. A surgical specimen of R-GBM from a 20-year-old woman was analyzed using whole exome sequencing (WES), whole transcriptome sequencing (WTS), single nucleotide polymorphism array, and array comparative genomic hybridization. The status of gene expression in R-GBM tissue was compared with that of normal brain tissue and conventional GBM tumor tissue. We identified 23 somatic non-synonymous small nucleotide variants with WES. We identified the BRAF V600E mutation and possible functional changes in the mutated genes, ISL1 and NDRG2. Copy number alteration analysis revealed gains of chromosomes 3, 7, and 9. We found loss of heterozygosity and focal homozygous deletion on 9q21, which includes CDKN2A and CDKN2B. In addition, WTS revealed that CDK6, MET, EZH2, EGFR, and NOTCH1, which are located on chromosomes 7 and 9, were over-expressed, whereas CDKN2A/2B were minimally expressed. Fusion gene analysis showed 14 candidate genes that may be functionally involved in R-GBM, including TWIST2, and UPK3BL. The BRAF V600E mutation, CDKN2A/2B deletion, and EGFR/MET copy number gain were observed. These simultaneous alterations are very rarely found in GBM. Moreover, the NDRG2 mutation was first identified in this study as it has never been reported in GBM. We observed a unique genomic signature in R-GBM compared to conventional GBM, which may provide insight regarding R-GBM as a distinct disease entity among the larger group of GBMs.

Magnetic Resonance Imaging Features of Rhabdoid Glioblastomas

PURPOSE

Rhabdoid glioblastoma (rGB) is a recently described, highly aggressive brain tumor, in which glioblastoma (GB) is associated with a rhabdoid component. So far only 21 cases have been reported and its imaging findings have not been studied in detail. In this paper, we present 11 additional cases and aim to depict detailed magnetic resonance imaging (MRI) features of this tumor in comparison with the previous cases of rGBs and our cohort of typical GBs.

METHODS

Retrospective evaluation of the glass slides of 249 GB patients disclosed 14 cases with rhabdoid morphology. Eleven of these cases with available MRI were included in the study. Immunohistochemistry was also performed. MRI and clinicopathologic findings were compared with those of previous rGBs and typical GBs.

RESULTS

(1) rGB is usually a large, well-delineated solid tumor with extensive necrosis, heterogeneous contrast enhancement, occasional hemorrhage, and cysts, (2) rGB may present at an older age than previously reported, but still in younger individuals compared with typical GB patients, (3) tumor dissemination in the form of leptomeningeal seeding and more rarely extracranial metastases is a feature of rGBs, although leptomeningeal seeding may not be as high as previously reported, (4) prognosis is poor in rGBs.

CONCLUSIONS

rGB is a new entity which has not yet appeared in the WHO classification of central nervous system (CNS) tumors. Understanding its clinical and imaging features may help to distinguish it from other tumors of CNS.